SR20DE Facts

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Drifter112
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SR20DE Facts

Odgovor Napisal/-a Drifter112 » 07 Dec 2006, 22:26

EDIT by Symon:Tema je postala prava biblija za vse ljubitelje SR20 motorja, zato naj jo povišam v "NE PREZRI"! :bow:

An SR20 overview - by Jason Steeves

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SR20DE Primer -- by Jason Steeves
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"When Nissan was doing extensive research in Europe in the late 80's developing the car that would become the Primera/G20, they decided that their original spec for a top speed of 210km/h was too low for the rigors of the Autobahn, and they realised that they would need to develop a new engine that was capable of putting out 150 hp... this spurred the development of the totally new SR20DE. Of course, it turned out that the engine was ready in 1989, a year before the Primera was to debut, so it actually first appeared in a Japanese domestic market Bluebird. However, there is no debating the fact that this engine was developed to power the Primera in daily driving at high speeds on the Autobahn..." *

The SR20DE engine that comes in all North American Infiniti G20's is a very robust motor. Designed in the late '80s for the new Primera, and brought into production around the world in the early 90's, this motor has stood the test of time and is still considered a very good engine by todays standards. The SR20 is showing its age and it's rumored that the high-tech QR family of engines, in the new Sentra SE-R, will soon replace the SR family. There are many different itterations of the SR engine around the world, sadly North America only gets the SR20DE.

SR20Di - Dual overhead cam, throttle body injection
SR20DE - Dual overhead cam, fuel injection
SR20DD - Dual overhead cam, direct injection
SR20VE - Dual overhead variable cam, fuel injection
SR20DET - Dual overhead cam, fuel injection plus turbo
SR20VET - Dual overhead variable cam, fuel injection plus turbo

There may be other variations but the above list isn't meant to be exhaustive. The SR20 engine family also comes in various chassis configurations: front wheel drive, all wheel drive and rear wheel drive configurations. The front and all wheel drive configurations are practically identical, only the transmissions are different. For example, the Japanese all wheel drive Pulsar GTi-R motor (SR20DET) will fit into the Infiniti G20 with minor difficulties. However, a rear wheel drive S14 Silvia SR20DET will not fit into a G20 without some serious fabrication.

SR20DE Features
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The North American SR20DE remains largely unchange over the years with a couple important exceptions.

Factory Features (North American SR20DE)
===========================
86mm x 86mm bore and stroke
Forged steel shotpeened and micropolished crank
Forged shotpeened rods

In 1994 the USDM SR20 went through a minor redesign as well. The intake manifold and head design changed the most. The earlier model (91-93) is known as a highport motor and the 94 and newer model is known as a lowport motor. This came from the intake manifold design and where it bolts to the head.
With the slight change in motor design also came a change in the cam profile. The earlier model cars, specially the 91-92 models, came with a more agressive intake cam. The 94-99 lowport motors came with a slightly detuned cam, but the redesigned head. The overall power output is the same at 140hp, but the cams are slightly less aggressive, by the tune of 16 degrees duration.

The P10 G20 (91-96) came with a 7450rpm redline. The redline on the roller rocker p11's is slightly lower. The 1999-2000 model s are 7000rpms and the 2001-02 is 6750rpms

In the year 2000 Nissan redesigned the SR20 motor one more time, this time changing from hydraulic rockers to roller rockers. This motor is still a lowport SR20 motor.

*More roller rocker info on the way*



SR20DE Potential
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Basic Performance
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The SR20DE responds very well to aftermarket modification. (Or, the SR20DE aftermarket is very good.) The SR20DE is rated, in North America to the tune of 140hp (145hp for year 2000+) at the crank. This equates to about 118hp-124hp at the wheels depending on the year. Adding all the basic 'bolt-ons'; intake, header, exhaust, will potentially put output over 140hp at the wheels. The addition of underdrive pullies, a good set of street cams and an aftermarket tuned ECU can bump the power numbers to over 150hp at the wheels.


Advanced Normally Asperated (NA)
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If you are looking for even more NA horsepower there are a couple different options. The most expensive is probably a stroker kit, made by JUN or Tomei. Less expensive, but still not cheap, is rasing the compression ratio and moving to a hotter set of cams. The DE block can be drilled and tapped for piston squirters, 11:1 compression ratio pistons, higher profile cams, upgraded valve springs, valves, retainers, injectors and, of course, a retuned ECU can bump the horsepower to 170hp at the wheels and beyond. Even with a stroker kit, high compression and all the goodies the most a livable street car might see is somewhere around 190hp at the wheels. Although that's pretty damn good, considering around a 65hp increase! Another JDM engine swap gaining popularity is the SR20VE swap. This is a good option for those who want more power than the standard bolt-ons will provide but don't want to go turbo. This engine is still relatively new and not a lot of information is available regarding mods such as headers and cams.


Turbo Performance
-------------------------------
Some would argue that the DE was ment to be turbocharged. It's certanly built for it. The stock DE block can take up to 500hp worth of boost before it will need to be resleeved with stronger material. Turbo options range anywhere from mild (180hp) to wild (600+hp). There is a whole science based on choosing the proper turbo for any application. It all depends on what you want to achieve. The old addage "big turbo, big power, big lag" isn't necessarly true anymore. Turbo technology has come a long way since then, by correctly choosing your turbo you can still get big power with relativaly little lag. Ball bearing center turbos can cut lag significally, but are expensive. Describing all the turbo options currently available for the G20 is an article all by itself. Look for it soon...


Additional Reading:
Links to other articles on the SR20DE, tuning, tech, maintenance, etc
- http://www.se-r.net/engine/index.html
- http://www.se-r.net/car_info/engine...nce_tuning.html

Sources:
* Summerized and translated by Camron Cavers from an interview with four members of the design team in the "Tuning & Dress-up Guide" for the Primera. (Japanese atricle)
Original Post - http://www.se-r-list.org/archives/2...5/msg02352.html
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Odgovor Napisal/-a Drifter112 » 07 Dec 2006, 22:26

Basic things to make the SR20 faster

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Intakes:

Intakes are probably the most common and least expensive bolt on midification you can do to your G20. They help the G20 get more air into the cylinders and help mid range to top end power.

Ghetto airbox modification/Stock Airbox Mod
This modification is done to the stock airbox. This modification entails cutting holes in the stock airbox to allow more air through the factory filter location. This modification usually does not gain any hp, but rather gives the motor a nice throaty growl, somewhat similar to a WAI setup. For many this is the first modification performed.

Warm air intake - (WAI): The most popular setup for G20’s is the Jim Wolf Technology Pop Charger. This solution provides a velocity stack that bolts to the MAF housing that provides a smooth entry for incoming air. The filter element bolts to the outside of the velocity stack and sits in the engine bay behind the battery. This setup is CARB certified. There are also many low cost WAI setups available right now that are comprised of a MAF adapter and generic cone filter. You can expect about 1-3hp with any of these setups. The main difference here is noise; these will make the engine noticeably louder under acceleration.

Cold Air intake - (CAI): The Cold Air Intake is a much more potent intake. The installation is a little bit harder, but the overall results are much more pleasing. The cold air intake will make a lot more midrange power than a WAI, and more top end power as well, about double what the wai produces. The three popular CAI setups right now are made by Hotshot (HS), Place Racing (PRI), and AEM. There is also a Stillen setup, but it’s a slightly different design. The HS, PRI and AEM units replace the piping from the throttle body all the way to the wheel well. They are all make of smooth, mandrel bent piping and with the use of silicone couplers place the MAF in the center of the piping, very close to the stock location. By moving the filter to the wheel well the air entering the motor is much colder, denser air, which helps with power. As well the length and size of tubing helps with resonance tuning. Resonance tuning is very much like sound tuning, where the pulse waves coincide with the open intake valves helping force air into the cylinder.

Larger Throttle Body
This modification doesn't gain any power on the dyno, but it does help with throttle response, it'll make the car feel more responsive. The stock throttle body is already rather large at 60mm.

Larger MAF
This modifcation will not free up any power on a N/A SR20. The only reason to upgrade the MAF is if you can max out the stock unit at 5.15V. Anything short of a large nitrous kit or turbo system most likely will not be able to max out the stock MAF.

Headers:

Headers are the best bolt on upgrade you can do outside of the motor. They can produce quite a bit of power, are rather inexpensive, and can be installed relatively easily.

Hotshot: Hotshot Performance makes by far the best performance header for the G20. They are dyno proven to produce the most horsepower and have gone through many revisions to “stay on top” so to speak. The hotshot unit is a 4-2-1 setup. The hotshot really boosts power output right around torque peak and gives very good top end power. Expect about 10-15 hp, depending on your setup.

AEBS: AEBS headers are older headers, but still very good. These provided very close competition to the HS header and in many argue they are a better header. They are a 4-1 design, which can cause some clearance issues on lowered cars. They do not provide any emissions revisions as well. This header helps over a very broad range of rpms and makes very close to what the hotshot makes as far as top end power gains. There are rumors that a revised AEBS header will be released and will produce more power and also provide emissions equipment bungs as well. Expect about 10-12 hp, depending on your setup.

Stillen: Stillen headers have been around for a few revisions, just like the HS units. They are either a 4-2-1 design or a 4-1 design, depending on the revision with the 4-1 being the newer one. These headers make good power as well, not quite as much as the HS units, but very close. The difference in power between the 4-2-1 and the 4-1 units is very minimal. The Stillen unit gives good low end power and will peak slightly lower in the powerband than the HS header. Expect about 8-10 hp, depending on your setup.

Pacesetter: The pacesetter header is a low priced header. It is very closely related to a first gen hotshot header. One of the models is coated with a cheap black paint that’ll burn off the first time it’s used, newer models can now be purchased with an optional ceramic coating. Expect 5-7 hp.

Other noteable headers are the S&S header (6-8hp, 4-1 design) and …. HP racing?

Catalytic converters:

Stock: This unit is very good, does not hurt horsepower at all, and helps reduce the poisonous exhaust gases; the stock cat is 2.5”

Aftermarket: The only reason to get an aftermarket cat is if your stock cat becomes clogged or damaged. They are an affordable replacement for stock. You can get a wide variety of different sized and applications. The most popular brands are random technology and Catco.


Exhaust System:

The purpose of an upgraded exhaust system is to reduce backpressure while keeping exhaust gas velocity as high as possible to increase the efficiency of the motor’s breathing capability. SR20DE powered vehicles seem to benefit the most from 2.25”- 2.5” exhaust in naturally aspirated form. Turbocharged engines like as large and free flowing exhaust as possible. The most popular and easiest size to fit is a 2.5-3” exhaust.
For any high performance exhaust you’re going to want to only get a mandrel bent exhaust system, crush bends rob horsepower and can also contribute to a raspy sound.
As for the resonator and muffler you’re going to want to find a perforated core muffler rather than a louvered muffler.
Some readily available systems that’ll bolt on to your G20 can be found through Greddy, Blitz, and VRS. There are also rear exhaust sections available; these replace your piping from the axle back and the rear most muffler as well. These setups can be sourced through companies like Remus, Sebring, Super Sprint, and Stillen. However, most people opt to have custom systems fabbed up at local exhaust or high performance shops. The most common setup right now incorporates a Magnaflow round muffler for the resonator and an oval Magnaflow muffler for the rear muffler. With a full cat back exhaust system you can expect to gain anywhere from 3-10hp depending on your other mods and stock exhaust system. This modification helps mainly top end horsepower.

Underdrive Pulleys:

Right now Unorthodox Racing makes pulleys for the SR20DE motors. They have a 2 pulley set that replaces the crank and water pump pulley and a 4 pulley set that replaces the crank, water pump, power steering, and alternator pulleys. They work by slightly under driving the accessories and also reducing rotating mass, each helping free up hp the motor normally uses to spin the accessories. A great feature about the pulleys is that they also prevent the water pump from cavitating at high rpms, stock it’ll start above 6500rpms. A must have for anyone planning to hot lap or track race their G20.
The two pulley set is good for about 4-6whp gains, climbing from a small 1-2 horsepower gain off idle, to a much larger 4-6hp at redline. The 4 pulley set is good for about 1-3hp more than the 2 pulley set, the installation is also quite a bit more difficult and time consuming. This mod is very deceiving and doesn’t feel like it helps as much as it does, due to the smooth, linear power gain, but is a great bang for the buck mod.


Lightened Flywheel:

There are two main options for this modification, lighten the stock unit to about 14lbs, or purchase an aftermarket unit that weigh in at 9-12lbs. To compare the stock flywheel is about 18-19lbs. Either setup will noticeably help your G20’s acceleration. This modification helps by reducing rotating mass, helping the motor and drivetrain accelerate faster. The purpose of the flywheel is to store potential energy and help the car start moving from a stop. However, once in motion the flywheel acts as dead weight and actually hurts acceleration. Reducing this “dead weight” helps the motor spin easier and more freely. Also, the lighter the flywheel the faster the engine decelerates as well. With a lighter flywheel you will have to rev the engine higher to keep from bogging from a stop.

Contrary to popular belief this modification will help when drag racing. You will have to adapt to rev the car higher off the line, but once in motion the improved acceleration of the car will help lower your ET’s. This mod is also great on a road course as it will help you more quickly and easily match rpms between gear shifts.


Timing:

For optimal performance on a stock motor dial in between 17-19 degrees timing and run 91-92 octane gas. Once modified w/ aftermarket cams you will want to back this back down, and it will vary between cams. Jim Wolf’s regular S3 cams like lower timing, 13 degrees has given the broadest powerband in dyno tests. If you are running a Jim Wolf ECU you’ll want to set your timing to 15 degrees, unless otherwise stated on the JWT ECU.


ECU:

The premiere tuner for Nissan ECU’s is Jim Wolf Technology. JWT can reprogram your stock G20 ECU for a variety of different applications. They can account for a change in injectors, MAF, the addition of cams, nitrous, a turbo kit, and even a different motor! They also can raise the rev limiter, remove the speed limiter (if there is one) and account for most changes in emission equipment.

Cams:

91-92 Intake cam
This is a great bang for the buck modification for 94-99 G20's. Usually costing less than $100 for the cam, this is close to the cheapest 6whp gain you'll find. At redline (7500rpms) the gains will be approx. 10-12whp. This intake cams has 16 degrees more duration than the later model cams.

JWT Cams

-Street Grinds
These cams provide great power gains from idle all the way to redline. Depending on the grind, your power band may vary. S3's are the most tame cams, they will increase power from idle all the way to redline. They have a very slight lope at idle, and should gain about 12whp at peak, with gains as high as 25whp at redline (7500rpms). The S4 cams can be used on the stock valvetrain, just like the S3's. The S4's will gain a little more power up top and will not fall off as quickly. But, they also lose some power down low in the rpm range. The idle on these cams is a bit more rough as well.

-Competition Grinds
These are JWT's potent race developed cams. The competition series cams are the most aggressive cams available for a hydraulic valvetrain SR20 motor. They must be used in conjunction with the JWT valve springs and retainers. A JWT ECU is pretty much necessary with this modification as well, as the idle is rather rough. There is a noticeable lope in the lower RPMs and there is a loss in low end power. However, in the upper RPMs these cams will gain more power than any other cam available. These really are not designed for a street car and should be used on a built motor.

HKS, Jun, Tomei, Toda, etc..
Not a lot is known about these cams. They are usually very expensive and are difficult to find. You can find anything from mild street cams to aggressive race cams from these manufacturers. A few SE-R owners have had good results with the larger Jun cams, although they seem to be very high rpm oriented cams, just like the JWT C series cams. The Tomei cams seem to produce good power throughout the powerband, but don't appear to make quite as much power up top as the JWT S3's do. Hopefully more information will surface about these cams.

Built N/A Motors

Pistons and Higher Compression
These usually are not very common modifications unless you're looking to extract every last hp out of your motor. Going with larger pistons will slightly increase the size of the combustion chamber. For example an 87mm 300zx piston will increase your motor from 1998cc's to ~2045cc. Not much of a change, but at this point every little bit helps. Higher compression is possible with new pistons. JWT forged 300zx pistons will raise the compression to 11.0:1, up from 9.5:1 stock. This will net about a 10whp gain all across the powerband, from idle to redline. With this modification you will need a reprogramed JWT ECU in order to avoid detonation.

Headwork
This is left to the professionals. Headwork will gain you power in the higher rpms. Good headwork usually won't lose any low end power. You'll most likely see anywhere from a 10-25% increase in flow. As far as power gains, it really depends on your other modifications and how extreme you go with the headwork. Some opt to even raise the compression by reshaping the combustion chambers, that will gain some extra hp as well.

Stroker Kits
These are only for the most serious of engines. They cost a TON of money and are extremely hard to obtain.

Extrude Honing
This really doesn't help too much on an N/A SR20 motor. You'll see a few hp from the power peak to redline. On a fully built motor you might see gains start a bit lower, and help more at higher rpms, but this should be seen as a final modification, where you're looking for every last hp.
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Odgovor Napisal/-a Drifter112 » 07 Dec 2006, 23:16

What's the difference between SR20De and SR20DE, and what's the difference between SR20DEL and SR20DEH?



Simply put, they are just there to differentiate between the 150hp engines found in the eZX, eGT, GT and Almera GTI spec cars, and all the other non 150hp 2.0l cars.

SR20De = all the 2.0l engined cars, that are not 150hp.

SR20DE = all the 150hp engined cars.

Thats the easy bit, lol.

The DEL and DEH were brought into play Oct.97, this was brought in because Nissan started to use an Electronic system for their parts finiding instead of the old Microfilm way. The system was known as the Nissan Fast System.

Now, the DEL and DEH came into play because this new fast system did not support lower case fonts, only uppercase fonts, so Nissan in their wisdom added the L for the SR20De labeled engines and added a H on the end for the SR20DE engine codes.

Hence looking for anything on the fast system, you searched for a DEL for the lower powered engines, and the DEH for the higer powered engines.

Now when the P11-144s were launched 2000, around that time, they got rid of the L, and the H and kept it to just DE on the latest fast system, this seems likely because they had now stopped the use of the higher powered 150hp SR20DE engines.
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Odgovor Napisal/-a Drifter112 » 10 Dec 2006, 14:50

300 HP NA SR20DE ( PRIMERA BTCC )

The pictures below are of the SR20 engine that was used a few years back in one of the European touring car championships. I received these pictures from a friend in Japan who works for Nissan in the Motorsports Development Section. These photos were released by Nissan for distribution.

This SR20 is normally aspirated and puts out around 300 hp. It is a full race engine, and although basically similar to our SR20DE's, there are significant differences. While many of use dream of turbo charging our normally aspirated engines, with this engine Nissan did the reverse. That is, this engine is essentially the turbo SR20DET from the GTi-R transformed into a normally aspirated engine


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The intake side of the engine
It uses a separate throttle body topped by a velocity stack for each cylinder. This setup results in a intake runner length that is shorter and straighter than the stock setup. The shorter length allows the engine to breathe easier at the high rpm's at which it operates while racing.

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The top of the engine from the intake side
Notice that there are two sets of injectors, i.e. TWO per cylinder!!. Check out the direct ignition system with separate ignition coils for each cylinder. This is probably borrowed from the 200SX. The valve cover is embossed with the word Nissan on the intake side and SR20 on the exhaust side

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The flywheel end of the engine
If you look carefully (large image), you can see the code 54C cast into the block. This is not the same block used by SR20DE engines. The 54C block was used in the beast-like GTiR. SR20DE engines used the 53J code blocks. This image also provides another view of the direct ignition, valve cover, and velocity stacks.

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The exhaust side of the engine
Without header/exhaust manifold. Notice the dry sump oil system at the bottom left
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Odgovor Napisal/-a Drifter112 » 10 Dec 2006, 15:44

Tuning Tips

Timing- Stopinje/nastavitev/zamik vžiga

Here is the all time cheapest hop up that anyone can do. Typically most SR20DEs have the timing set to 13 degrees or less from the factory. I have seen as low as 10 degrees on a brand new factory fresh car. You can safely run up to 15 degrees on regular gas on most SR20DEs. For best performance on a stock engine, put in 92 octane and dial in between 17 to 19 degrees. This has been proven by recent dyno testing on a stock car to give up to 6 more hp at the wheels. Remeber if you have your timing turned up this high you MUST use 92 octane fuel. Do not exceed 17 degress of advance if you have a JWT ECU.

Don’t tolerate any detonation though. Detonation will kill your engine quicker than lard and coconut oil will kill you! I am putting the detonation warning in here because the timing pointer on the engine can be easily bent which could cause you to accidentally over-advance your timing! It happened to me so be careful! If you have the JWT ECU, set the timing at 15 degrees. On the dyno I have not seen any difference between 15 and 17 degrees with a JWT ECU although bottom end snap might feel a little better. It is better to be safe at 15 than on the edge at 17 for only a perceived difference in throttle response. Be sure to disconnect the TPS when adjusting the timing and remember that the JWT NOS module requires that TPS terminal 1 and 2 be shorted out when setting the timing.

Synthetic Oils and Lubricants- Sintetična olja in maziva

This is a good non-envasive hop up part. I am going two open a whole can of worms here but as far as I know, Mobil 1 is the only synthetic oil to get for your engine. Not only is it the cheapest but it works the best. There is a lot of industry insider information on oil and Mobil 1 has been tested by many OEM manufacturers and found to come out on top. I don’t want to start a big thing about it and cannot divulge my information's secret sources, but trust me on this one. Granted my test data did not include Valvoline, Castrol or Havoline Synthetic but it did include ALL of the famous synthetics who will remain nameless on the record. In fact, one oil that is highly regarded by list members that is sold as a direct marketed product is in fact nothing but rebottled Mobil 1 for twice the price.

Recently, my buddies at Cosworth report that Royal Purple seems to have good bearing life in the XD Indy engine but for the most part Cosworth uses Mobil One as factory fill. I have had personal good luck with Motul but have no scientific test to prove that it is super good. Adam Saruwatari tells me that Motul has cut his engine wear by 3 fold. Nismo uses Motul in their Group C LeMans car as well as the GT390R. Their testing showed that Motul was excellent.

For gear oil I have found that under racing conditions Redline MTL had superior shifting characteristics but for me has led to faster gearbox wear. On the street this may not be an issue. Nissan Motorsports has had good luck with regular Redline Shock Proof gear oil. Personally I like Motul gear oil. It seems to shift nearly as well as MTL and better than Mobil 1. It has a heavier body so it should have better shock protection for the gears than MTL. Granted this is not based on any scientific evidence, just observations and common sense.

As a non oil related note, Redline Water Wetter is legitimate and really has a reduction of water temp by about 20 degrees F, good stuff.

These super lubes can free up about 1-3 hp, have much better gearbox and engine operation in very cold weather and directly help performance by keeping your engine in top shape for longer.

In my opinion, you still need to change the engine oil at about 3000 miles for best results even with synthetics. I have noticed that the oil pressure at hot idle starts to drop at about 1500 miles with dino oil and 3000 miles with synthetics. I believe that this is caused by the oil’s shearing down under hard use. That’s where my 3000 mile opinion comes from. It is not scientific oil analysis but is based on some data. BTW, I have never had an oil-related failure in any engine I have ever built while following these rules.

The hydraulic lash adjusters on the SR20 engine do not like thick oil. Thick oil causes them to pump up and become noisy. This is especially true of 1991 year engines. For these engines you must run 5w-30 or 10w-30 oil. To get good protection under hard use with these light oils it is, in my opinion, important to run synthetics. These thinner oils provide less viscous drag which can give more hp and better fuel economy.

To my knowledge, the best oil filters are genuine Nissan. This is mostly because of the anti-drainback valve which goes a long way to reduce cold start wear. Also, the bypass valve flow rates and the particle pass through size have been determined by the factory as the best compromise between effective filtering and good flow with low pressure drop. The factory filter also has a thicker shell and better crimping that your typical aftermarket filter so it is less likely to blow off if, for instance, the bypass valve sticks or the oil is super thick on a real cold day.

Headers- Izpušni kolektorji

Headers are probably the biggest bang for the buck item in the modification list. I have had experience with two different ones both of which offer better construction than what is typical of aftermarket headers. These headers are the Hotshot and the Stillen. Both of these headers are constructed of heavy gauge mild steel that is ceramic coated for appearance and long life. The ceramic coating may aid catalytic light off under cold start conditions which is helpful for OBD-II cars (1995 and later).

Both of these headers have been redesigned since my last update. The Hotshot header has been given larger diameter primaries of 1-3/4", up from the previous 1-5/8". This makes the primaries have less of a neckdown from the exhaust port exit. The material has been thickened to 14 gauge, up from 16 gauge used previously. This cuts down on noise and reduces the chance of the pipes cracking. The new Hotshot gives about 3-5 more wheel hp than the old one according to dyno tests on my car and another closer to stock car.

The Stillen Design has been changed to a short runner 4-1 design. Its power output is better according to Stillen but our testing resulted in nearly the same amount of power as the old design. This is surprising as 4-1 designs generally are better for top end power. The Stillen header still makes slightly more power below 3500 rpm than the Hotshot but the Hotshot outpowers it by at least about 4-5 more top end hp.

Testing on the dynojet show that the Hotshot is good for about 10-15 wheel hp, with highly built cars getting more power and stock cars getting more toward the 10 hp side of the scale, and the Stillen, 8-10. I have personally tested the Hotshot but am relying on other list members data for the Stillen unit. The hp on the Stillen unit peaks about 500 rpm lower than the Hotshot. The Stillen unit boosts bottom end, where as the Hotshot does not come into play until near the torque peak.

If you are going to keep your car pretty stock or really need bottom end torque, the Stillen is a good choice. If your car is modified with camshafts and other bits of hop up stuff the Hotshot is preferable although both perform well in either role due to the forgivingness of the tri-y design.

I have installed both headers and the fit is very good on either. However some list members have reported fitment problems on both. My own personal experience is that both designs fit well. The O2 sensor location on the Stillen unit is a little low for the 98-99 Sentra SE and requires rerouting of the sensor wire which is kinda self-explanatory. The EGR fitting on the Stillen header requires a little fudging to install. This is not a problem but can be a little hard to do for the unmechanical. First you have to loosen the two 12mm bolts that hold the EGR tube to the EGR valve. Then start the big EGR fitting nut on the header side, then tighten the EGR valve nuts a little. Then fully tighten the header fitting big EGR nut. Finally fully tighten the two 12mm nuts on the EGR valve.

The fit of the Hotshot is flawless and does not require much fiddling but if you do have a slight misalignment the above procedure will work also.

They have been some complaints of a rattle or chirping noise that both headers make at approximately 2500 rpm. To me it sounds like a cricket chirping. This is not harmful and not all cars do it. I am not sure of its root cause. The new generation Stillen and Hotshot headers do not seem to make this noise.

The intermediate pipe gasket blows out in short order on both headers. The fix is no big deal, the metal gasket from a 300ZX intermediate pipe will work or applying high temp O2 sensor safe red silicon. Either solution will work well. The Z gasket must be modified so the bolt holes line up but that can be done in seconds with a Dremel tool.

The new Hotshot header solves this problem with the addition of a copper gasket that is just about blow-out proof. You must remember to re-torque the bolts after a few days to allow the gasket to take a set. The new Stillen header has no gasket here so the problem is cured!

The have been a few new companies to come out with an SR20 header recently:

Pacesetter
This header looks like a cheap rip off of the old style Hotshot. It also ripped off the experimental secondary crossover pipe that was featured in one of my SCC articles. Too bad they did not read the article to find out that it did not work! It has thin tubing and is painted with a cheap black paint that instantly burns off and wreaks havoc with your 02 sensor. The flex pipe is of low quality and will not last long. The generally cheesy construction won't last long either. This header produced the least amount of power of all evaluated. It is also the least expensive and does produce a good gain of about 5-7 hp so it might have some merit.

AEBS
This header distributed by Group 5 is a beautifully made full race 4-1 design. It is made of thick wall, ceramic coated steel with nice welds. The AEBS header features a merged collector which is a very nice, powerband-widening feature. The AEBS header produces the widest powerband of all SR20 headers and nearly as much peak hp as the power king, the Hotshot. It has produced as much as 12 wheel hp on some cars. This is surprising as 4-1 designs usually favor the top end of the powerband. In my opinion the AEBS or the Hotshot are the best headers for the SR20 currently on the market. Unfortunately the AEBS has a few minor quirks. It is one piece and more difficult to install unless you have access to a lift and it is lacking any provisions for the EGR system. There are no instructions on how to disable the EGR with the header either so many buyers of this header suffer from driveabilty problems. This is because the disconnected EGR system sucks air making the car run too lean at part throttle. It is very simple to disable the EGR so Group 5 should add the instructions to the header. If you own an ABES header simply disconnect the vacuum line to the top of the EGR valve and plug it.

S&S
The S&S header is a small diameter, long length primary tube 4-1 header. This makes it a good low end and mid range header. It gives a 6-8 hp advantage over a wide powerband. It is also painted which is a disadvantage for looks and life. It is also low in price. It is a good header for the money if you have a stockish motor.

Exhaust Systems- Izpušni sistemi

Perhaps the most popular first piece of speed equipment is the exhaust system. On our SE-Rs, the power produced by the exhaust is not always consistent. The gains of a cat back system are not super huge and mostly at high rpm. We have seen gains of 1-3 hp on a typical SE-R although some SE-Rs have gained as much as 8 wheel hp. This is because of variance of muffler design even within one model year. Some Classics and NXen have a washer-like restrictor plate deep inside the muffler. It is impossible to spot by just looking at the car. If you have one of these restricted exhaust systems you can expect a big gain. Unfortunately I do not have a production number or VIN range of these affected cars so I cannot narrow down exactly which vehicles have these mufflers. These cars get about 6-8 hp when you upgrade the exhaust.

200SX owners can benefit from a low restriction exhaust because it will reduce the chance of getting an EGR temp sensor MIL light.

G20’s have a pretty hard to improve upon exhaust from the factory as stock.

GReddy makes one of the best exhausts tested. It has only about 2 psi back pressure and is sort of quiet. I have not tested the HKS or Borla system. The HKS system is supposed to be quiet and the Borla, I’ve heard, is loud. The Borla system also has a restrictor plate. I believe list member Ian Lyn and Shell Black have some experience with a gain in performance after removing the restrictor but the noise level went up also. Merlin Johnson has done extensive testing of different sizes and type of exhaust systems. His testing methodology is very valid and believable.
Quite a few list members have complained that the Stillen exhaust is too loud and rusts out but for the $135 price, I doubt that you could do better at the corner muffler shop. Stillen will most likely come out with a super high quality all stainless system soon.

For you do-it-your-selfers here are some general guidelines. If your engine is stock or if you are limiting yourself to bolt-ons, limit your pipe diameter to no more than 2" or you will lose some bottom end with no applicable gain on top. If you are to the point where you are getting into camshafts and headwork, 2.25"-2.5" from the cat back piping is appropriate. For turbo applications, 3" is the way to go. Try to avoid the typical muffler shop crush bends. You can buy mandrel bends from Kinsler, Burns stainless, or Bassani. That way your local muffler shop can cut and section these for smooth, non-crush bends in your system.

Do not enlarge your header collector to bigger than 2". I have found that even with my very built 206 hp NA motor that going to a 2.25 collector lost about 6 hp through all of the powerband. After the cat, Shell Black has proved that there may be some power to be found with fairly built NA motors by going to 2.5 inch pipe.

Straight through mufflers are by far the lowest backpressure. The Walker UltraFlow, Apex'i, or Magnaflow are some common ones. Stay away from the generic louvered core glass packs. Even though those are straight through they have incredible backpressure, often more than stock. Look for a perforated core. This is a pipe with lots of small punched holes. The Walker and the Magnaflow mufflers are real loud by themselves and require a pre-silencer.

The Walker Magnum glass pack that most auto parts stores sell here is good for this. It has a perforated core. Make sure that you are truly getting a perforated core! A 24" long Walker with an UltraFlow or Magnaflow creates a system with about 2 psi back pressure that is decently quiet. Dual path, straight through, perforated core mufflers like the Edelbrock should work well also, although I have no direct experience with them. You still need a pre-silencer with them.

The common Turbo-style mufflers are not very quiet and have lots of backpressure, as do the famous Super-Trap and the Flow master, so don’t bother with them.

If you are so inclined, you can do your own testing by welding a pipe bung right after the cat and running a silicon hose to a 0-20 psi gauge in your car. Then you can do 3rd gear runs through the rpm range recording backpressure. Use an old fuel filter as a surge accumulator to smooth gauge readings. Make sure all of the gas is gone! Better yet, use a new plastic one so you won't blow anything up!

Unless you are turbo or nitrous only and are going for the maximum in power, do not bother with removing or gutting your cat. Unless the cat is melted it only has about 1.5 psi of backpressure or less and only affects power by 1-2 hp if that. This is even with a built NA motor. With a turbo or NOS you will lose some power. However we did run mid 12's in Ryan's turbo car with a cat and still passing California's stringent dyno smog test. Remember, this (gutting the cat) is also a big time violation of federal law! Gutting the cat will cause a MIL light on post '95 SE-R’s which is to be avoided come registration time. There is little to be gained with aftermarket cats either, although they are priced well and if you need to replace your stock cat they can be a good value.

Recently Courtesy Nissan has started to offer a very high quality 2.5" 100% polished stainless exhaust system designed with feedback from Shell Black and King of Beers Jeff Naeyaert. This exhaust seems very promising for being a good power producer, durable and inexpensive - a definite best buy.

Air Intakes- Filtracija zraka

The most common are the JWT POP Charger (POP stands for Performance Optimized Program) and the Stillen which are almost identical. Both are washable and reusable and come with a nicely machined aluminum velocity stack base. Be sure to oil them with K&N oil after cleaning in detergent and water. Don’t go crazy with the oil, a light even coating is fine. Too much oil can contaminate the hot wire in the MAF.

RS Akimoto supposedly make an intake for the Classic but I have never seen one. I think list member Justin Choi might have tested one, verifying it with MAF voltage readings and found it to flow less than the JWT POP.

The HKS powerflow does not seem to filter well. I put one on a white rag and tapped it and lots of dirt went right through it. One of my friends tested one on a flow bench and found it flowed better than the POP, but the Stillen and POP has more than enough flow capacity for our motors and personally I would rather have a filter than a boulder strainer.

I have no direct experience with the GReddy unit but it appears to be made of a fine foam which could filter better I suppose.

Justin Choi has done a lot of filter testing so he would be a good source of information.

You can expect 1-3 hp with these units. If your engine is built, they will not necessarily give you more power but will allow your engine to reach it’s potential by eliminating the intake restriction of the stock air box.

If you want to test your own filters, simply use a multimeter to measure the voltage to the MAF. The higher the voltage, the more air you are flowing. Remember also that temperature and barometric pressure affect the readings so it is important to use only back to back data, not week to week.

Perhaps the most potent air intake is the JWT POP combined with the CAI or cold air intake by Place Racing. I have tested this combo and found up to an 8 hp gain with 3 more peak hp. This part is one of my bang for the buck recommendations. Hotshot is planing a CAI also. It is a nice looking chrome plated part and produces just as much power as the place unit in our testing.

To complement the CAI, I have blocked off the hot water passages in my intake manifold and throttle body. I do not recommend this to anyone who lives where it gets below freezing but for my native sunny California it is OK. The hot water prevents the manifold and throttle plate from icing up under cold conditions. The throttle may also need to be cleaned more frequently as the hot water keeps the PVC blow-by residue crap from condensing on it, as well. On real cold mornings my car has a slight hesitation for about 30 seconds but that is about the only negative effect that I have personally experienced.

Now my car consistently has the same hp, dyno pull after dyno pull. All of you who have done dyno work know that the power drops about 3hp after the first run. The manifold used to get baking hot like the valve cover but now only gets slightly warm to the touch.

The CAI stays cool to the touch even when everything else is burning hot. The CAI can reduce your ¼ mile time by close to 2/10ths and make your car a lot more consistent on a hot day

ECUs- Krmilne enote/računalniki

So far in my experience the only ECU worth considering at this point is the JWT unit. Without slamming anyone, to my knowledge most of the other ECUs on the market have some degree of code mistakes in them. JWT is also the only company to my knowledge at this time that can do reliable programming on Post 1995 OBD-II ECU’s. Without revealing specifics, when examining the code in other companies ECUs, mistakes have been found on just about all of the other manufactures chips. In fact, one famous manufacturer did not change one single bit of code in the program! They merely socketed the PCB, and put an E-PROM WITH THE STOCK CODE IN PLACE! They charge 600 bucks for this piece of crap. They advertise in all the major magazines. I won’t name a name but their ads feature an Eclipse burning out with a sunglassed ponytail looking dude driving it.

If you want to buy another brand of ECU, ask these questions.

Can you raise the rev limit?
Can you eliminate the speed limit?
Can you compensate for larger injectors across the entire operating range?
Can you compensate for a different MAF?
Do you use a Horiba A/F monitor?
Do you understand offsets? Do you know what invalid time is?
Can you program a OBD-II box?
If they cannot answer all of these questions then go to JWT and save yourself some aggravation. I am not paid by JWT so I am not biased, but I'm amazed by their technical competence and I am very hard to impress most of the time. They are also the only tuner in this country who has pushed the limit of SR20 (and Nissan in general) development.

JWT’s ECU significantly improves transient throttle response making the car feel much more lively as well as providing more total advance at WOT. The JWT ECU also leans out the A/F ratio at WOT to an optimal 12.6:1 as the SR20 tends to run rich under these conditions. That’s a reason why the fuel pressure riser does not work too well on our cars.

The JWT ECU adds up to 8-10 hp is some parts of the power band and generally adds 3-5 hp on top. The ECU can take up to 0.3 off your quarter mile time. If you follow the same driving pattern with the JWT ECU, it has the potential for better fuel economy, as well. Premium fuel is required and 15 degrees of set timing is recommended.

For the 200SX, the JWT ECU is almost essential as this car is saddled with an annoying 109 mph speed limiter and a crappy 7100 rpm fuel cut. The ECU really adds to the driving pleasure of these cars.

On an esoteric note, under racing conditions the SR20, especially in an NX, can be subject to thermal runaway. This manifests itself when the air temp gets into the 80’s or if you are drafting in a pack (only do this on the track kids!). The temp goes up which triggers detonation which causes the knock sensor to tell the ECU to pull out timing which causes the temp to rise. This goes on in a viscous loop until the engine overheats big time. Unless you immediately drive slow for a few minutes the engine nukes. In the heat of battle you sometimes forget to check your gauges and boom! I myself blew about 3 engines like this back in my racing days.

Anyway, the JWT ECU limits the amount of knock retard and for the most part, stops this problem. If you are planning to do track events this almost makes the JWT ECU a mandatory item. JWT can also custom program the ECU for high compression and turbocharged applications for a reasonable fee. In fact, if you are going to run 11:1 compression, a JWT ECU is essential if you plan to run on pump gas.

Cam Shafts- Odmične gredi

So far, the JWT cams are about the only ones that work well on the market. One famous Honda tuner (THE MOST FAMOUS Honda tuner) came up with some cams for the SR20. I observed their mule car in action at the strip. It idled like a bridge ported rotary engine which is to say not at all, the MIL light was on and the thing was running blazingly fast 16 second ¼ mile times!

The JWT cams are ground on new genuine Nissan billets so the factory base circle diameter can be maintained. This is important for correct hydraulic lash adjuster function and correct valve train geometry. These are important factors for operating noise and valve train life. Other companies regrind the base circle smaller to get more lift and duration on a stock cam. To do this correctly would require an asymmetrical grind on the lobes to match valve events because of the change in the rockers angularity and motion ratio. Some custom shims under the hydraulic lash adjusters would be needed to maintain proper lash. The wear pattern on the rocker arms would not be optimal either due to their change in angularity. Most companies that do regrinds do not supply an asymmetrical grind or correction shims!

Other common aftermarket problems such as premature wear due to incompatible metals rubbing on each other are eliminated by using genuine Nissan cam billets.

JWT offers two different grinds, a street grind and a race grind. On a stock engine, the street grind is clearly superior. In my testing, the street grind lost no bottom end power (the bigger the cam generally, the less bottom end) and was good for a solid 12 hp. The gains were recorded from 4000 rpm on up and their was no penalty in fuel economy. As cams are the thing that can upset the OBD-II and emission systems the most in general, the engine was tested on a sniffer type smog machine. It put out 6ppm HC and 6 ppm CO at idle. At 3000 rpm the output was 6 ppm HC and 11 ppm CO. This is well under the limit (by almost 10 times!). Although these cams are not CARB approved, the effect upon pollution seems minimal.

I have yet to test them under the new IM240 smog dyno and plan to avoid that for as long as possible! The street cams have a reasonable idle with only a slightly detectable lope. The OBD-II system has remained happy. The race cams did not do too well on a stock engine loosing power except above 5500 rpm. Headwork and 11:1 compression are necessary for these. I have not tested the race grind on a high compression engine yet but will do so soon.

As an update, JWT has released a second generation street cam that has the same 260 degree duration of the previous grind with about 0.030" more lift and faster lobe profiles. This cam was optimized to be the most radical grind for stock springs. This cam works exceedingly well giving my car more than 6 additional wheel hp over the older grind. Shell Black also got about 5 more hp over the older grind on his motor with a stock bottom end.

Also as an update, I have passed the new stringent California dyno test with my fully built motor with flying colors. Ryan's 12 second turbo car has passed also. This proves that clean does not mean slow. It also proves that the government should not concern itself with what's under the hood if what comes out of the tailpipe is clean.

JWT also has a 264 degree and a 268 degree cam for special order only. You must have high compression and headwork to run these cams. My car has gotten about 3-5 more hp above 6500 rpm with these cams but they did cost significant bottom end hp. I have since returned to the regular street grind as this grind is much more torquey and fun to drive.

JWT will also soon release a Pro-Series cam that will have about 264 degrees duration with a whooping 12mm of lift. These will require special valve spring and titanium retainers. With their ultra fast profile, these cams should give near VTEC like top end while retaining reasonable bottom end. To exploit these cams you will need high compression and headwork. I will be testing these cams soon and will report how they work

There are a few new promising cams that have come out since I last updated these pages. All of these cams are of good quality and are pretty expensive.

JUN
I only have anecdotal information on these cams. I have heard through JWT that these cams have very poor idle characteristics and they require a custom ECU to start the car or idle. JWT has had to do custom ECU's for people with JUN cams just so they could start their cars! They are for extreme top end only and are not very streetable. They are ground on new billets. I myself do not have any experience with these. JUN parts are of very high quality and are very expensive.

Tomei
These high quality cams are imported by Group 5. These have shown much promise in Group 5's initial testing with a 12 hp gain to the wheels on Chris Pinthong's bolt-ons-only NX2000. These are also a good quality billet cam but are pretty expensive. Tomei has a very good reputation in Japan like JUN. Look for more testing to be done in the near future.

Comp Cams
Now a major maker of domestic car cams tries to get involved with the import market. Comp Cams are ground on what appears to be JUN billets. They are priced like JUN billets, almost 2X more than JWT cams. Dave Coleman of SCC has tested both the JWT and the Comp Cams and tells me that the Comp Cams feel very mild and do not feel as strong as the JWT cams. He has not dynoed the Comp Cams yet but will soon. Comp Cams has two grinds, a mild and a very mild. Dave told me the very mild is almost not any different from stock and is not worth the effort.

They are a couple of other low buck alternative grinds available for the SR20 that work to varying degrees. The first is the SR20DET "European" grind exhaust cam that Stillen and Nissan Motorsports carries. Although it is pretty inexpensive there are a few problems. The SR20DET uses a mechanical cam with no hydraulic lash adjusters. Mechanical cams require gentle acceleration ramps on the cam lobe flank. When used with the hydraulic lash adjusters in the SR20DE, these flanks keep the valve open a few thousands of an inch for about 10-20 extra degrees of crank rotation. This makes the engine think it has a real big cam at idle. Thus these cams lope like a JWT race grind or worse even though they only have about 8 degrees more effective duration.

For a classic 91-92 SE-R or NX you only use the exhaust cam as the intake cam has the same duration as the DET cam. For the other years you can use both. Supposedly these cams can give up to 6 more hp although I have never confirmed that. Our IMSA race car had the exhaust cam and I could feel a bit more power above 5000 rpm. That engine idled like a fully built motor and I was surprised that we were never protested. I don’t think this cam set could pass a smog test and they would most likely freak out the OBD-II system although I have never tested either.

Another little trick is to use a 91-92 intake cam on a 95+ SE-R. This cam has 16 degrees more duration than the stocker and according to the guys at Nissan Motorsports gives 6 more hp. Ed Wolf and Kurt Sussman run these cams in their 200SX’s. This cam idles fine in this application and should breeze by a smog check.

Do me a favor and DO NOT CALL JWT to debate with Jim or Clark whether these cams are better than their cams. They are not and JWT does not have the time to argue with you.

One of my SCC articles made mention of the alternative cams and JWT was flooded with calls from people wanting to argue that their cam set was not worth the money. The JWT cams have at least twice the potential power gain as the alternatives and whether you think it’s worth the money is up to you as a consumer so don’t waste their time on this point.

[Editor's note from Kurt Sussman. I easily passed a California smog check with the 92 cam. Since this comes up too often, I'll post the numbers here for the 91-93 intake cam, and for the 95 intake cam. In 1994 there were two different intake cams, and I'll post that when I have it in front of me rather than give out misinformation.

Year Ex. Duration In. Duration Intake Opens Intake Closes Exhaust Closes Exhaust Opens
91-93 240 248 13 55 3 57
95-97 240 232 5 47 3 57

The open and close are relative to TDC (intake open and exhaust close) and BDC (intake close and exhaust open).

This is only the cam timing; the lift is greater with the 91-93 intake cam as well (about 15%).

As far as performance, the 91-93 cam will make a difference, but Searl (with the JWT street cams) has never lost a race to me; roll-on or from a standing start. Until early 98, we had identical configurations except for his nitrous oxide kit, which was turned off for most of our races.

Adjustable Cam Sprockets - Nastavljive jermenice odmičnih gredi

Turbo magazine has reported huge gains in Honda and Acura engines with the addition of adjustable cam gears and dyno tuning. In my testing with JWT Street cams, the gains were inconclusive. I tried about 25 different combinations of advancing, retarding, lobe separation angle spreading and tightening with no gains worth keeping over the stock location.

JWT has gone through pains to grind their cams with the proper lobe center straight up. If I got 2-3 more bottom end hp, I would lose 5 on top and vice versa. The best alternative timing was intake cam advanced 2 degrees. This had a gain of about 3 hp in the midrange and 1-2 on bottom end with loss of only about 1-2 on top. This setting might be good for street only driving or autocross where bottom end snap is important. When I deviated by more than 8 degrees of the factory lobe center, the OBD-II system triggered a MIL light.

When building my 11:1 motor the gears were very important, allowing me to correct the cam timing despite milling 0.040 off the deck and head. When you mill things the cam timing retards and you can use adjustable gears to correct it. In fact anytime you mill your head and block like when doing a rebuild, you should use adjustable timing gears to restore proper cam timing.

Stillen claims good gains with the adjustable gears and stock cams but I haven’t tested that myself. The gears are cheap and it would make a good project for someone besides me to do.

JWT and Stillen make gears. The Stillen gears are two piece and are infinitely adjustable. The JWT gears are one piece and are adjustable in 2.5 degree increments. Both are about equally easy to use. The JWT gears are safer by being impossible to slip or vibrate apart and are cheap. The Stillen gears are more expensive, but are real trick looking and can be adjusted in very fine increments which could be an advantage.

If you are going to play with your cam timing I suggest that advancing the intake cam slightly in the 2-3 degree range will most likely have a good effect on bottom end and midrange with only a slight loss of top end. This would be a good place too start.

Headwork- Obdelava glave

Headwork entails enlarging the intake and exhaust passages in a head to allow for more flow. Good headwork entails subtle reshaping, not just hogging the whole port out bigger. Generally, good headwork leaves the floors of the port alone since most of the flow activity in a port is near the roof of the port. The roof is the outside radius of the bend going to and from the combustion chamber and by inertia, most of the air wants to flow up there. Good headwork usually rounds the floor hump which is the transition from the valve seat to the floor of the port. Stock, this is usually a sharp edge which causes non-laminar (turbulent) flow separation.

The object of good porting is to increase flow as much as possible while keeping the port volume as low as possible to maintain as high of a flow velocity as possible. Big ports have low velocity at low rpm. This results in a loss of bottom end power due to the lack of energy available in the moving gas column behind the valve. The gas column has inertia which helps fill the cylinder, especially at low RPM. Generally porting your head will cause some loss of bottom end power. Good head porters might be able to increase flow in the head up to 40 percent with no loss in bottom end but that is usually for American Iron heads which are terrible to start with. Modern Japanese engines don’t usually see as big gains as their design is much better to begin with. Gains of 10-20 percent are typical with a modern Japanese motor.

The other major area of headwork flow gain is in the valve job. A large percentage of gain can be in the valve job alone. The best valve jobs are called multi angle valve jobs with three or more distinct angles. The main angles are the throat cut, which is a 60-70 degree cut that blends the port wall to the seating cut. The seating cut is a 45 degree cut which is the sealing surface for the valve. This critical cut should be 0.040-0.060 wide for a multi valve engine like an SR20. Finally there is the top cut which is a 30 degree cut which blends the seating cut to the combustion chamber. The purpose of these cuts is to help the air flow smoothly around the valve, especially when the valve is starting to open or close.

Another valve job trick is to place a 30 degree back cut above the 45 degree seating cut on the valve itself. This helps the air get around the valve better especially at low lifts. A five angle valve job uses two extra cuts to make the transition even smoother. The best valve jobs are radius valve jobs which are a 3 or 5 angle valve job which is hand blended after cutting for a perfectly smooth transition. The quality of a valve job is very important because it can contribute up to 50% of the flow gains that headwork will get you.

The best valve jobs are done on a Serdi machine. The Serdi is very high precision which insures that all the valve angles and depths come out equal. Most low price shops use stones. Stones can give a good valve job but the stones must be dressed frequently and dial indicators must be used to insure that the seating surface remains concentric. Stones require a highly skilled person who is conscientious of doing a good job. A butcher can make a big mess with stones.

Unshrouding the valves is an operation where the edge of the combustion chamber is cut back by about 25% of the valve diameter so that the wall of the combustion chamber does not block the air going past the valve into the cylinder.

Polishing the combustion chamber removes sharp edges that can glow red hot and trigger detonation. It also makes it harder for carbon to stick. Polishing should be limited to the combustion chamber and exhaust port. The intake port should be no smoother than 220 grit as maintaining some boundary layer turbulence is good for good bottom end. This turbulence makes the port virtually a little smaller at low flow velocities.

Personally, my belief is that the best head porters for the SR20 head are DPR (Dan Paramore Racing), JWT and B.C. Gerolomy. My own personnel heads are done by DPR and Nissan Motorsports uses B.C. Gerolomy. JWT requires no further introduction here!

Beware of bad headwork. Perhaps the most famous Honda builder who advertises very heavily and sponsors many 10 and 11 second Hondas does awful commercial headwork. I have seen heads from that shop that have huge, lumpy uneven ports. The valve jobs were 1 angle that were cut so deep that the valve would have to rise about 0.040 to get out of the huge crater of a seat cut! Talk about shrouding! The valves were cut so deep that I am sure that the stem tips would have to be faced off to maintain proper valvetrain geometry IF that was done! Perhaps it was the new guy that did these heads but I have seen more than one of them. This shop’s work could not be all bad because of their track record, but I have yet to see a good off-the-shelf head from them. Stuff like this is why many Honda owners complain that their cars end up slower than stock!

My DPR head is a marvel of detail. The head is fully deburred to remove all sharp edges that can cut you during assembly and cause stress risers. Then it was ported by Dan Paramore, keeping an eye for increasing velocity rather than ultimate flow. My objective was to build a torquey engine with no loss of bottom end power. Dan cut down the valve guide bosses where they intrude into the port and smoothed the hydraulic lash adjuster boss where it hangs down into the intake port. This annoying feature was added to the 95 and later low port head.

The valves had the stems turned down for better flow to about 6mm below the valve guide. That way they would block less of the port's cross section area. Dan also reshaped the valves going way beyond the customary 30 degree back cut. Finally Dan swirl polished the valves. Swirl polishing is polishing putting a hurricane looking pattern on the face of the valve. This is supposed to increase flow. The shaping considerably reduced the weight of the valves which should give more rpm headspace before valves float and the classic SR20 rocker arm flies off. To my knowledge DPR is the only company that puts this much detail work into the valves.

The main advantage of the DPR head is Dan’s combustion chamber work. Dan welded up the edges of the chamber to increase the quench. Quench is the area where the piston top comes within 0.040 of the combustion chamber near the edge of the cylinder. The quench zone squishes the fuel air mixture to the center of the cylinder where it can be easily burned. This reduces the likelihood of detonation and increases efficiency. This feature found in all of DPR’s stage 6 heads sets them apart from other tuners and is the reason that I chose them. Increasing quench does raise the compression ratio, so if you are doing pistons and stuff, this must be considered.

The DPR head has a combustion chamber volume of 43cc’s down from the stock volume of 46cc. This raises the CR on stock pistons form 9.5:1 to 10:1. 10:1 is fine on pump gas with the stock or off the shelf JWT ECU. If you are running JWT’s NOS 100 shot ECU the program will have to be changed a little at this CR. If you are running NOS with someone else’s kit, you will have to retard the spark a little under NOS operation. I think around 4 more degrees than you already retard for a 100 shot would be a good starting point although I have not tested that.

If you use the Nissan Motorsports flat top pistons the CR gets close to 11:1. With the planned JWT forged big bore pistons the CR becomes 12:1 which is not streetable but the dome can be machined off to get 11:1. With 300ZX pistons the CR is close to 12:1 but it is easy to machine the domes off of these also. To run 11:1on pump gas requires a special program from JWT. The stock ECU will not work. I do not have much experience with big (100+HP) NOS units and real high compression but you must be careful! More ignition retard and richer fuel mixture are appropriate here. Detonation can result in rapid death! JWT has a 50 shot program for 11:1 available.

My DPR head resulted in a power increase of 10hp above 5000 rpm with no loss of power below that at all! That is testimony to Dan’s skill. The bottom end felt better but the dyno did not register that so I can not claim that. When revving the engine in neutral it was much more responsive to blipping the accelerator pedal. If Dan was to build an all out power head, I feel that their would be another 5 or so hp available at high rpm’s but some low end power would be lost. Dan could have made me some bigger valves but I did not want to pay for that!

The high port classic head (91-93) is superior to the low port head (94-present). The changes to the head were done to improve hydrocarbon emissions. The high port head has long intake ports that bend smoothly around the hydraulic lash adjuster and shoot straight into the cylinder. Unfortunately for pollution's sake this long intake port necessitates having the fuel injectors farther back from the intake valve. This causes the port walls to get wetted with fuel. This fuel is sucked into the engine in-between shifts and on overrun causing the mixture to spike rich.

To eliminate this Nissan went to the current low port design with it’s short intake port and close coupled injectors. Unfortunately the hydraulic lash adjuster must now hang into the intake port obstructing flow. Also the approach angle of the port no longer has such a straight shot into the cylinder either. I believe, although I have not personally tested, that the older high port head is good for about 5-10 more hp than the low port head. To substantiate my theory I have noted that when looking at Japanese Performance magazines, no Japanese tuner uses the low port head in their crazy SR20s.

If anyone has dyno results of a fully developed high port head please submit them to us so we can post them and compare them to project SE-R’s low port head.

As an update, DPR has done some R&D on the high port head and is now able to extract about 25% more flow out of them, up from the 10% increase seen with my head. Dan feels that this could result in 10-12 more hp for his latest creation. Dan has also developed a new valve spring set and new titanium retainers as well as 1 mm oversize stainless valves. George Roffe, Mike Palhs and Ben Benavides have all or some of these latest mods in their motors and we eagerly await dyno results.

Pistons- Bati

There are a number of choices here. Nissan Motorsports has the European and Japanese spec pistons that are flat topped (the stockers have a slight dish) that raise the compression to 10:1. This should give about 5 more hp. Nissan Motorsports also has the SR20DET piston which lowers the compression to 8.3:1 for turbo motors. These pistons are available in the standard Nissan size grades in standard bore. This is ok for lower mileage motors but for high mileage motors you might need an oversize piston. Please don’t bother Ron at Nissan Motorsports by asking him if these pistons will work in your motor at xxxxxx miles! Get a FSM and a bore gauge and figure that out for yourself first, then call him! The Nissan Motorsports pistons are cast, but they are a good quality cast piston and can take relatively high amounts of abuse. This means no real high boost levels (much above 14 psi) or huge nitrous hits (certainly not more than 100 hp).

A late model 300ZX VG30DE piston can be used with some modification to the connecting rod. This piston is 87mm up from the stock 86mm which will give you 2045cc. The small end of the connecting rod must be ground down by 0.010 on either side to give the rod enough running clearance. I did it on a belt sander being careful to mike the rod several times along the way. Be sure to put a slight chamfer on the pin bushing after you are done. I used a deburring tool and polished the edge with some 400 grit wet dry paper and some honing oil.

The VG30DE piston will give you 11:1 on a stock type combustion chamber. On a DPR stage 6 head you must mill off the dome of the piston. This can be easily done on a lathe or mill by any competent automotive machine shop. Mill the dome completely off making a flat top piston. The VG30 DE piston is a high quality cast piston.

JWT will soon release a forged 87mm piston. It will have a slight dome to give 11:1 with a stock configuration head. The dome could be removed for a lower compression. Forged pistons are much tougher and can withstand detonation and stress much better than a cast piston. The JWT piston will use a high silicon alloy which allows tight piston to wall clearances and also has a super strong, lightweight tool steel piston pin.

You might be wondering if forged or cast pistons are better. Cast pistons are made by pouring molten aluminum into a mold. Nissan cast pistons are pressure die cast in an inert gas atmosphere. Pressure casting results in a stronger, denser part with less inclusions than the low tech pour in the mold method. A genuine Nissan cast piston is dimensionally more stable than a forged piston and can run extremely tight piston to wall clearances, as little as 0.0004"! Tight piston to wall clearances help with oil consumption issues, hydrocarbon emissions and piston ring life. The bad thing is that cast pistons are more brittle and tend to crack ring lands under detonation.

Typically the number two ring land cracks on Nissan pistons. Under lots of detonation, nitrous or boost, the pin boss of the cast pistons can crack also. Usually this incident claims everything south of the intake manifold! Granted Nissan cast pistons are a high quality, strong cast piston and most list members, even you hard core ones will not get to this point.

Forged pistons are made by smashing a heated billet of aluminum into a forming die with extreme force. This results in an compressed microstructure with good grain flow in critical areas such as the pin boss. Forging alloys are also ductile and strong in nature. Forged pistons offer superior strength and toughness resisting fatigue and cracking. Forged pistons can be made thinner and lighter due to their superior strength. Forged pistons can take detonation much better than cast pistons.

Forged pistons can also handle the strain of high boost and Nitrous. All racing pistons to my knowledge are forged. The disadvantages of a forged piston are that it must run a larger piston to wall clearance than a cast piston. This is due to two reasons. The first is that forging alloys grow more with heat, the second is because of the violent nature of forging; a forged piston has more internal stress and is not as dimensionally stable.

Old school forged pistons needed to run as much as 0.009" piston to wall clearance. These pistons sound like a diesel engine, rattling like crazy. Due to recent advances in piston alloys and skirt design, modern forged pistons can be run as tight as 0.006-0.003".

Pistons that run on the high side of this scale will still rattle. Ones on the low side can be fairly quiet. Usually this has to do with the silicon content of the alloy. Low silicon pistons are the ultimate in strength and toughness but require big clearance because of the metal’s high expansion rate. These are pistons used in top fuel drag racers or the real nasty turbo Hondas. High silicon pistons run tighter clearances and are slightly less ductile but are still much stronger than cast pistons.

I would not recommend a low silicon piston for street use no matter what. It would be noisy, wear rings quickly and be a oil burner after not so many miles.

JWT pistons will be high silicon and can be run at 0.003". The are almost as quiet as stock pistons. If the skirts are coated with a dry film lube like Swaintech poly moly, bringing the clearances down to 0.0015 or so, they should be as quiet as stockers.

If you are going to push the edge with turbo boost, nitrous or are going to do some real racing, forged pistons are the way to go.

By going to 11:1 CR with pistons, my engine gained at least 10 hp across the board, from off idle to the fuel cut. High compression was one of the best all around mods so far. High compression increases thermal efficiency and lowers the BSFE (Brake Specific Fuel Consumption). My car gets a consistent 29-33 mpg despite spirited driving. As I have stated before, a JWT ECU is mandatory with 11:1 to prevent engine-destroying detonation regardless of piston type.

I may be trying to build a big gun engine within the next year or so. I will sleeve the block so a 90mm bore will be possible. Forged, slightly dished pistons will be used for an 11.5:1 cr. Then a KA24 crank with a cut down snout and welded up thrust surfaces will be used to bore and stroke the entine to 2400cc. Amazingly the KA24 crank almost drops right into an SR20!

JWT pro-series race cams will be installed. More displacement can mask some of the bad characteristics of big camshafts like lack of low end power and lumpy idle. My goal is 185 wheel or 215 crank hp with even more low end torque!

Crank, Rods, Bearings, Machining, Balancing, Coatings, Manifolds, etc.- Glavna gred, ojnice,ležaji,obdelava,balansiranje,prevleke,kolektorji

The SR20 is blessed with a near bulletproof bottom end. The crank and rods are forged steel unlike the typical cast iron that most American motors run. The rod bolts are a beefy 9mm. The crank features rolled fillets, an uncommon strengthening operation used usually only for racing or heavy duty parts. The rod bolt registers are spot faced, leaving a generous amount of metal around the bolt holes, a traditional weak area in connecting rods.

Both the crank and rods are subjected to a severe shotpeening from the factory. Shotpeening microforges the surface of the part making it stronger and harder while leaving the interior soft and ductile. This step can improve the fatigue strength of a part by over 100% and is usually reserved for high end racing parts. The main caps are tied together with a stiff aluminum girdle which improves bottom end rigidity significantly. This feature is usually found in all out race motors. These design elements produce an engine that is nearly bulletproof. I have seen motors with over 100,000 miles on them with the factory honing marks still visible in the cylinder bores! The number of list members in the 100,000 Mile Club is a testament to the durability of the SR20.

The only catastrophic engine failures that I know of (Tom Paule and Zak Nilsson) were the result of low oil levels with spun bearings. Chuck Nibbana’s super trick engine also mysteriously disassembled itself but that might have been because of improper clearancing. I have screwed up 3 SR20’s myself but that was the result of not watching the temperature gauge while racing IMSA and SCCA. Gross overheating was an understatement. Clark Steppler of JWT has never seen a catastrophic failure that could be traced to the engines fault, either.

The same bottom end of our US model SR20DE also is used for the turbo SR20DET so we have a lot of headspace before we start to challenge the strength of the bottom end. The stock parts can be used until the hp climbs well into the 200’s. So bring on the NOS, turbo boost and compression! We have run Ryan Besterwich's turbo car (formerly Searl's) as high as 20 psi of boost which pushed the car into the low 12's with a completely stock bottom end with no harm. His car has over 80k miles on it and is still going strong. I estimate that his car is putting out over 400 hp with the stock bottom end! If detonation can be controlled the stock bottom end is pretty strong!

If you are building a hot street SR20, I recommend leaving the rods alone. By doing the traditional beam polishing you will be removing the factory tough shotpeened surface. If you reshotpeen the rods after polishing they will have to be resized and straitened as proper shotpeening distorts the parts. It is not likely that a local shotpeener can do as good of a job as the factory either. The same goes for the crank. It won’t hurt to do these traditional race prep steps but it is probably not worth the effort on the SR20.

If you do prep and re-shotpeen your rods make sure that the piston wall oil squirter hole does not get blocked or peened over. This hole sprays oil on the thrust side of the cylinder helping with lubrication and keeping the engine quiet.

In fact, I might say that no matter what you do to build a naturally aspirated motor, if you keep an 8000 rpm or less redline, you don’t need special rods.

I do not have any personal experience with the well-publicized-by-Turbo-magazine, Metalax treatment process but have heard good things about them. I do have plenty of good personnel experience with shotpeening solving many parts breakage problems. Recently I have had very good luck with cryogenic treatment preventing breakage of drivetrain parts with high powered SE-Rs and I am currently building a VG30DE motor using cryogenic treating extensively.

For extreme use in killer turbo motors running near 20 psi of boost or for those of you running 100+hp NOS units, racing rods may be in order. JWT can get Crower rods. I believe these rods are machined from 4140 billet. I am using Cunninham rods in another engine. These rods are a little lighter than Crower and seem just as high quality. Carrillo makes excellent rods also but they would be a custom application and take 6-12 weeks for delivery. These racing rods do not have the oil squirter hole in them which could result in slightly shorter life of rings and pistons.

The rods and pistons should be balance to within ½ gram and the crank dynamically balanced. I have found that Nissans are generally within 1 gram from the factory! A typical American car is usually off by as much as 5-12 grams! I like to polish the journal surface of the crank. You can have a local machine shop do it using the lightest grit of polishing paper belt. You don’t want to remove so much material that the crank dimensions change, just reduce the RMS of the surface by knocking off the peaks of the machining marks.

The factory Nissan bearings are strong and durable. I recommend running bearing clearances in the middle of factory spec on a typical street motor. Clearances on an all out racing motor can be set on the looser side of factory. When buying bearings, Clark Steppler of JWT has told me (and I have also observed) that if an engine has any kind of mileage on it, the next tighter bearing size can be used other than the number that is stamped on each journal of the block and crank. Remember to mike and bore gauge all the journals to confirm proper dimensions before assembling. If you don’t have access to these , at least use plastigauge to make sure that you are in the ball park.

When boring or honing a block, it is better to use a torque plate. A torque plate simulates the stress of a cylinder head being bolted on your block. With a block that was machined with a torque plate, the bores will remain straight when the head is bolted on. Usually the block will distort and the cylinders will become out of round accelerating wear and reducing the effectiveness of the ring seal when the head is bolted on. Granted this is a small difference but is important if you want to build a good motor. For this reason the main caps should also be bolted on and torqued when the block is being machined.

Boring and honing should be done on a Sunnan CK10 machine. This is a high precision machining center that makes the honing of a good round bore almost idiot proof. Since today’s low tension rings require a smooth surface to seat properly, plateau honing after the dimensional honing reduces the RMS of the surface for lower friction, better sealing, less oil consumption and longer life. JWT has pioneered the use of plateau honing on the SR20 and has the process figured out for a smooth bore surface that will still allow the rings to seat. When properly machined with a torque plate and plateau honed, it is possible to have an engine that leaks down at 2% or less! [Editor's note: Nissan specifies that up to 10% is acceptable; most SR20DEs leak down at close to 5% (source: senior mechanic at Falore Nissan)]

JWT is the only company in North America to my knowledge that has a torque plate for an SR20 engine. JWT is most likely the best company to machine your SR20 block. JWT can also machine your block for SR20DET piston coolers. Piston coolers are oil jets that squirt oil onto the underside of your piston dome to help lubricate the piston pin and to help keep the piston cool. As aluminum starts to lose strength above 350 degrees, piston coolers can help quiet a bit. The SR20DET uses piston coolers as does the 11:1 cr SR16VVL N-1 spec motor. This Japan market hyper motor makes 200 hp from only 1600cc!

Since Nissan feels that this 11.6:1 motor needs piston coolers it is probably a good idea to put them in yours. The piston coolers have a spring loaded valve so they only open at higher rpms to maintain good oil pressure at idle and in bumper to bumper traffic. In my motor there was a noticeable drop in water temp once the coolers were installed. To my knowledge JWT is the only company that has the fixturing to machine a block for these piston coolers. Talk to Clark Steppler at JWT for machining.

When building a killer motor it is a good idea to replace the main cap bolts with the ones found in the SR20DET. These are about 20% stronger. Nissan Motorsports stocks these.

I am a believer in special coatings. Coatings are great for adding to reliability or to help control factors such as heat so special tolerances can be used. At the advice of Nissan Motorsports I used Swain tech coatings. Unlike the other to-be-named coating houses that use off the shelf coatings, Swain develops their own in-house coatings that are much more sophisticated. Where most other companies have a one layer coating, a Swain coating might have 3-4 different functional layers. I use Swain tech gold thermal barrier coating on my pistons. This is a severe duty 3 layer thermal barrier that reduces heat transfer by about 25%. This helps protect them from detonation and Nitrous abuse. By keeping the heat out of the pistons, I can run an amazingly tight piston to wall clearance of 0.0004 inches. That is 4 ten thousandths of an inch! My engine does not burn oil at all even with water-thin 5w30 Mobil 1 oil.

I also use Swain poly moly dry film lubricant piston skirt coating. This coating uses molybdenum disulfide and tungsten disulfide for a dimensionally stable heat conducting matrix. This is better than the teflon that most other companies use because teflon distorts and creeps under load. Teflon is also a heat insulator. Since the pistons cool themselves by conducting heat through the skirts, it is not to good to insulate them. Poly Moly can help tame the clatter of forged pistons. Poly Moly also tightens your piston to wall clearance by 0.0014 or so inches so you may have to compensate in your bore machining for this added clearance.

The guys at Nissan Motorsports tell me that poly moly significantly cuts piston and cylinder wall wear. Next time I go through the motor I will probably coat the valves and combustion chamber to protect them also. One of my friends had a 20 degree drop in water temperature, 300 rpm faster turbo spool, and 300 degree higher EGT's with a fully Swain coated motor. On my hopefully 700 hp Twin Turbo Z motor, I will be using Swain coatings on just about everything from the bearings to the undersides of the pistons. I believe that these coatings are like a cheap insurance policy.

Swain also makes slippery flow improving coatings, heat dissipation coatings, wear resisting coatings and stealth coatings that are not detectable!

List member Kurt Sussman is planning to build, test and manufacture a short runner intake manifold. When running computer simulations with Dynomation’s software, gains of up to 15 hp above 5000 rpm with losses of only 2-3 hp below 3000 were noted. This seems to indicate that Nissan sacrificed lots of top end power to gain a little below when designing the manifold. I noted that Nismo’s race manifold as well as GReddy and JUN’s race manifolds have short runners. The 196hp SR20VVL also has a short runner manifold. As these manifolds are designed for the RWD S13 and S14 chassis, Kurt took it upon himself to design one for the FWD cars. Yeah Kurt! We will be posting the results of this manifold as Kurt get around to it. However, he just had a baby girl which should postpone his manifold development for quite a while. If anyone else wants to do it, let me know!

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Nazadnje spremenil Drifter112, dne 10 Dec 2006, 17:44, skupaj popravljeno 1 krat.
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Odgovor Napisal/-a Drifter112 » 10 Dec 2006, 17:43

Extrude Honing- Honanje

Extrude Honing is a process where an abrasive putty is forced through your manifold or other difficult to port areas at a high velocity, removing material. Extrude Honing is great because it can port areas where it is otherwise impossible to do so, like in the middle of your very long runner manifold or deep inside your manifold's plenum chamber. Extrude honing is also very good at equalizing manifold runner flow.

Smaller more restrictive areas in the head act like a venturi so the putty flows faster there. Faster flow equals more cutting action and thus the Extrude Honing process by nature removes material where it's needed the most. This cutting mechanism is very good at producing runners that flow equally.

We tried Extrude Honing the manifold on project SE-R. This is the shorter runner manifold for the low port, post '93 head. The end results were mixed. Although the Extrude Honing performed extremely well on the flow bench, as the folks at Extrude Hone said it would, the dyno tested power increase was minimal.

On the flow bench the Extrude Honed manifold flowed a whopping 15% more than the stock manifold. Runner to runner flow which varied by about 13-14 cfm per runner stock had the variance cut down to less than 1 cfm per runner. With these excellent results we eagerly bolted on the manifold. By a SOTP evaluation, it was thought that the manifold improved throttle response and top end power. When the manifold was dynoed, the results were disappointing as the motor only gained one peak hp while losing one hp below 5000 rpm. Past the power peak until the fuel cut, the motor gained 3-4 hp. Although these gains seem small, they were repeatable through 4 back to back dyno pulls.

This shows that increasing the intake manifold's flow does not help too much even on a fairly modified SR20. Obviously the manifold is not a major choke point in the induction system. On an engine with race cams the gains would be larger as our manifold seemed to do the best at the very top end. Our computer simulation still indicates that a shorter runner manifold will help quite a bit. This is because the shorter runners will resonate at a higher rpm, improving cylinder filling through passive supercharging. This resonance tuning does not rely on pure steady state flow gains like extrude honing does. We are eagerly waiting for Kurt Sussman's short runner manifold, though we may have to wait until his baby graduates from high school!

Since the classic or pre-94 manifolds have longer, more curved runners, they have greater internal scrubbing losses due to the increased surface friction of the longer, deeper boundary layer (the still air near the runner's walls that does not contribute to flow). Perhaps this process would be more beneficial on one of these manifolds.

So in short, if you have an engine with just the easy bolt on parts, the Extrude Hone process most likely will not help much if at all. If your engine is really built with cams, headwork, compression, etc. and you are interested in getting every bit of power, you might consider it, but it would be a finishing touch type of modification.

If you have a killer high revving NA or high boosting turbo motor it might definitely be a plus.

Unorthodox Racing Underdrive Pulleys- Napenjalci

Being skeptical of the claims for big horsepower on the Unorthodox Racing web site, we ordered up a set of their underdrive pulleys to do some extensive dyno testing. Joe at Unorthodox told us via a phone conversation that he felt that the pulleys would be good for about 5 hp on the SE-R.

When received, the pulleys were obviously CNC machined from billet aluminum and anodized a nice shade of blue. They were significantly lighter than the stock bits. We measured the TDC mark in relation to the keyway to make sure that the TDC mark was right on. It was. Unfortunately the TDC mark is the only one on the pulley so timing the car without a dial back timing light is impossible. Not a big deal for us as we have one of these timing lights but possibly a problem for the average joe. We suggest that Unorthodox add marks in 5-degree increments to the pulley instead of just a TDC mark.

To install the pulleys, we removed the passenger side wheel and wheelwell splash shield, exposing the front of the engine. An air impact was then used to remove the main pulley nut. The 10mm bolts holding the water pump pulley were removed with the belt still in place to prevent them from spinning. Two 6mm bolts were used in the existing holes to lever the stock main pulley off the crank. I don't really recommend doing this as it is real easy to punch a hole in the front cover this way. Use a puller or back up the bolts with a peice of thick metal to prevent damaging the cover. To get enough clearance to completely remove the main pulley, the passenger side motor mount had to be loosened and a jack placed under the motor to lift it slightly shifting the engine enough to get the pulley off. The new pulleys were installed in reverse order.

The stock belt for the water pump and AC compressor could be retained but a shorter belt was necessary for the alternator and power steering. We used a Bando p/n 6PK-1000 belt to replace the stock belt which was purchased from World Pack, a nearby parts house (1-800-733-2277). Bando makes genuine Nissan belts so I figured the quality of this replacement belt should be good.

After running the car, my SOTP estimate of power gain was small, about 1-2 hp. The engine felt more eager to rev and there was less drag when the AC compressor kicked on. I plugged in a CONSULT to test for charging function and overheating. The battery output stayed above 12 volts with all electrical accessories going full blast, including my aftermarket PIAA lights and 200-watt stereo cranking. When I made the electric windows go up and down at the same time the voltage dipped to 11.9 volts but I seriously don’t think that is a realistic estimate of potential power demand. I don’t think you would be caught in a very hot, very humid, foggy rain storm at night while broken down on the side of the road, engine at idle with every single light on, fogging up the windows while making out with your girl (or guy) stereo blaring and get a bug to roll the windows up and down to the beat of the music while waiting for the tow truck! If you do this frequently you may discharge your battery with the underdrive pulleys.

I tried to make the car overheat in bumper to bumper traffic on an 80-degree day, plus high speed cruising and free revving the motor to 7000 rpm for a few minutes. The coolant temp never went above 94 degrees C. I also did some violent slalom maneuvers to test the power steering. There was no sign of power steering pump up. The AC was perhaps a little less effective but it was hardly noticeable. After all this testing I conclude that the pulleys are at least safe. I think that under racing conditions the car may even run cooler as the stock water pump is prone to cavitate at over 6500 rpm.

Some list members have been concerned that the underdrive pulleys lack of an inertia ring as the one in the stock pulley could have some negative effects on motor life. I believe that this is not true. The SR20, unlike most domestic motors, has a fully counterweighted crankshaft and is internally balanced. It does not rely on a counterweight on the front pulley and flywheel to give dynamic balance like Ford or Chevy engines. Highly modified domestic motors are internally balanced at a great cost but us Nissan owners get that stock! I believe that the damper on the stock pulley is mostly to damp out accessory drive noise. With the underdrive pulley in place there actually seems to be less idle and high rpm vibration. I could not detect any increase in accessory drive noise but my car is sort of loud.

The next step was the acid test on DPR’s Dynojet chassis dynamometer. Amazingly the pulleys were good for a maximum of 6 hp over stock! The increase was about 2 hp at 2000 rpm rising in proportion with rpm to 5 hp at the power peak to 6 hp at the rev limit. The smooth gradual increase of power deceptively made the SOTP feel less. Normally most mods put a hump somewhere in the powerband that is easy to feel. Not so for the underdrive pulleys. Their seamless addition of power was very hard to feel. Being a skeptic we ran the car three more times to see if it was a fluke. All three runs yielded the same results.

At $189 list price these pulleys get our bang for the buck award! There are often group deals for less on the se-r mailing list.

Unorthodox has introduced a 4 piece pulley set that includes the power steering and alternator pulleys also. I have tested these and found perhaps a small 1 hp gain over the old 2 piece set. Shell Black has found a larger about 2-3 hp gain in his testing. Surprisingly I can feel a larger SOTP difference with the 4 piece set. Taking our suggestions, Unorthodox has improved the pulleys by adding a steel sleeve under the front main seal for longer life and is now adding all of the correct timing marks. The new product is even better.

We have also tested the pulleys extensively on the racetrack at temperatures over 100 degrees and found that the pulleys significantly reduce water pump cavitation induced overheating. Despite thrashing on a road course which is much harder on a motor than drag racing, we have yet to see any increase in wear on the motor.

Big Bore Throttle Bodies and MAFs- Večji vsisni/sesalni kolektorji in merilci pretoka zraka

I recently tested the RC engineering big bore throttle body. This throttle body is 64mm vs the stock 60mm. The workmanship and attention to detail are superb. The throttle body casting is honed to tight tolerances so a good idle can be maintained and the throttle shaft is aerodynamically profiled with streamlined button head bolts that are staked, much like OEM. Although it felt like it was giving a lot more power in my SOTP evaluation, on the Dyno no power increase at all was registered just as I had previously predicted. My theory is that it improved throttle response so much that the engine seemed a lot more powerful. However, I think this mod is worth while just because of the vast improvement in feel and response. Perhaps with more mods, the engine will need the additional flow and the TB will actually help.

I also tested using a big 80mm MAF from a late model Maxima using a custom programmed JWT ECU. My engine is getting close to the point where it can top out the stock ECU but not quite yet. Even through the Maxima unit is nearly 45mm larger than the tiny stock MAF, I did not gain any power except for about 2-3 below 4000 rpm! My theory on this is that the larger hole helped the CAI resonate better at lower rpm. I don't think bigger or bored out MAF's like Stillen sells are worth it unless you are turboed or your engines are modified to the point where they can pull more than 5.15 volts on the airflow meter. This is the point where the stock MAF is maxed out.

Spark plugs and Ignition systems- Vžigalne svečke in Vžigalni sistemi

There is a lot of controversy on the list on what is the best, most appropriate sparkplug for our cars. My opinion is yet another one but at least it is backed by years of racing experience and recent dyno testing.

Heat Range of plugs- Temperaturna stopnja svečk
Sparkplugs come in many heat ranges. This is so the plug can be matched to the type of use an engine receives. For low speed, short hop driving, the plugs electrodes must stay hot enough to burn away and self-clean fouling carbon deposits. For this type of driving a hot plug is needed. For high speed racing at high rpm, the plug can become too hot and glow like a diesel glowplug causing pre-ignition and detonation. This can quickly destroy an engine. To prevent this a cold heat range plug is needed.

The length of the insulator of the center electrode determines a plugs heat range. You can tell a cold plug from a hot plug by looking at the center electrode’s insulator. If the porcelain insulator is short, it is a cold plug. If it is long and extends deeply into the steel shell of the plug, it is a hot plug. This is because a cold plugs short center electrode has a short path to conduct heat out of the electrode. A hotter plug has a longer path and dissipates heat more slowly.

Most listmembers seem like they are unaware of matching the spark plugs heat range to the type of driving that they do. I wince when I think that many are squeezing nos or pumping turbo boost with the stock hot plugs.

In my opinion the best spark plugs for the SR20DE and DET are the stock Genuine Nissan NGK platinum plugs. I like a decent platinum plug. Platinum is a noble metal with a high melting point. Being almost inert, it is highly corrosion resistant even at high temperatures. That is why a platinum plug lasts about 3 times longer than a conventional plug. When used in the plug's electrode it resists erosion much better than steel.

Stock Nissan plugs have platinum in both the center and ground electrode for really long life. Most aftermarket platinum plugs only use platinum in the center electrode. I prefer for most engines, even the stock ones, to run the PFR6B-11 spark plug. This is the middle heat range for the NGK plugs. SR20 powered cars come with PFR5B-11 plugs, which are one heat range warmer. Originally when the SR20 was first introduced, the cars came with PFR6B-11s but they were fouling out during port storage where the cars are continuously being started, moved a few feet, and shut off. The countermeasure to high warranty on low mile sparkplugs was the switch to the hot plug.

The PFR6B-11 works well on high compression, turbocharged or NOS powered cars. For running extreme boost (more than 18 psi), a big shot of nos (more than 100 hp) or really high compression (more than 11:1) the cold PFR7B-11 plug is necessary. This plug will be on the edge of fouling during regular day to day driving so it can be considered a race only plug.

The SR20 has a shallow included angle of the combustion chamber. This makes for a quick burning, detonation-resistant chamber. I have also found that shallow included angle chambers for the most part do not like extended tip plugs. When experimenting with extended tip plugs I have found that the engine loses about 3-4 hp across the board. Many aftermarket plugs are extended tip. The theory behind extended tip plugs is that the extended tip puts the electrodes in a more turbulent section of the combustion chamber, thus helping them stay clean of fouling.

In the SR20 an extended tip plug puts the electrode too close to the piston dome screwing up flame propagation, thus losing power. This is important to consider if your are deviating from the Stock Nissan recommendation. Make sure that the tip of the plug that you are buying does not extend further than the stock plug’s tip. If you are running flat top or domed pistons, this is even more critical as the tip of the plug is even closer to the piston dome.

The SR20 has a powerful stock ignition that can fire through turbo boost and NOS. Gap the plugs at 0.045". If you experience misfire under squeeze or high boost (and the rest of the ignition system is in good condition, like the cap, rotor and wires) you can close the gap down to as small as 0.020" to prevent it. Go down in 0.005" increments until the misfire stops. Higher cylinder pressures cause by big NOS or high boost requires smaller gaps with the stock ignition. The smaller gap loses a little power but this trick can tide you over until you can get that snazzy turkey roaster ignition.

High Power Ignition- Zmogljivejši/močnejši vžigalni sistemi

I haven’t run across a SE-R that has needed this yet but I suppose that over a 100 shot of nos or 18 psi of boost might need a high power ignition. Jacobs ignitions are crap. I would not bother with them. I prefer an MSD 6A or better unit. I have never needed an MSD on an SR20 yet but I have had very good luck with them on other cars including racecars. The Crane Hi 6 has gotten rave reviews also but they seem prone to burning out (two of my friends have been stranded because of a burnt out Hi-6). These ignitions are very powerful, capable of firing the spark plugs for over 30 degrees of crank rotation. Just the thing for high cylinder pressures.

I have a Nology coil booster on my SE-R. It seemed kind of hokey but I installed it. It has allowed my car to run smoothly even with the plug's electrodes completely burned off. When the coil booster was unplugged the car would barely run so I guess it works well. The Nology coil booster is the only easy way to hop up a 200SX’s ignition as the coil is an integral part of the distributor.

I believe I have found the limits of the stock SR20 ignition system. On Ryan's turbo car, when exceeding 10 psi of boost we developed a misfire which required that the plug gap be closed to 0.020". Even this was only good to 14 psi before misfire started again.

On my 11:1 compression NA motor misfire was happening until I closed the gap also.

So on really built cars I now recommend the MSD 6A or SCI ignition system. On 95 and later cars with an internal coil, MSD makes an external coil conversion kit for Hondas that also works on our cars. Just be sure to cut the primary conductor from the stock coil and fill the resulting hole in the distributor cap up with silicone or some of the extra power from your new coil will be wasted.

As a note, these ignition systems don't seem to work too well with Nology wires. I use either stock or NGK wires.

These high power ignitions will not give you much more power but they will eliminate frustrating misfire and help starting and low speed driveabilty.


--------------------------------------------------------------------------------

OTHER PLUGS- Izbira svečk

Bosch Platinum
I hate these plugs. They have a weird center electrode that is flush with the insulating porcelain. What happens is that this electrode quickly erodes so it ends up being a depression in the porcelain, making the spark shoot out of a hole. Sparks like to propagate from sharp edges so I think they have a hard time getting out of this hole.

These plugs will absolutely not work for long in high compression, high rpm, boosted or NOS applications. The are marginal on a stock engine. In my experience they work OK for a few thousand miles then start to idle roughly and on modified engines misfire under load. It amazes me that an OEM level supplier like Bosch can make pieces of crap like these.

Some listmembers have recently dyno tested these plugs on stockish engines and have found them to be OK. This included some used plugs that were at least 20k miles old. My personal opinion is that these are pretty bad for most stock motors. The VG30 in my Pathfinder will barely run with these plugs. Kit Wetzler also experienced poor driveabilty in his NX2000 with these plugs.

[ Ed note: This is Mike's opinion of these plugs based on his personal experience. Go to Bosch Platinum vs. NGK Platinum Spark Plugs for a comparison of the two. -MM ]

Bosch Plus 4
Although I have not had any experience with them, Chris Pinthong and Dave Coleman have tested them and found them to work well. These plugs have an unusual design with 4 ground electrodes much like a rotary engine plug. Hopefully they are much better than the regular Bosch Platinum.

Beru
These plugs have a silver conductor for the center electrode. Since silver conducts electricity better than steel or copper it is reportedly better. The electrode material is still steel so I don’t think that these are much of an advantage.

NGK V plugs
These work fine, just change them frequently. Be sure that the tip does not extend further than the stock plugs.

Split Fire
I call these Miss Fires. They have an extended tip that the SR20 hates. The dual ground electrodes may have some merit by creating more sharp edges for spark propagation but this is moot when the extended tip causes hp loss.

Champion, AC and others.
I don’t have any experience with these. Make sure the heat range and tip length is appropriate for our motors. I think that these brands have some premium labels that have unique electrode configurations to have more sharp edges for spark propagation. Some list members have had good luck with these.

The main thing to remember with SR20s is that the plug’s tip length must be close to the stock plugs or power loss will result and the heat range must be appropriate for the intended end use or engine-destroying detonation may occur.

_____________________________________________________________


Reader's Contributions- Prispevki/nasveti bralcev

Here are some suggestions from one of the original 14 second club members, Pat Griffith. These are how some common bolt on parts have affected 1/4 mile times on his car

Pat writes:

JWT ECU -- lowered 1/4-mile time by .26 seconds; increased trap speed by almost 1.93 mph. Runs were about a month apart at the same track.
Header -- lowered 1/4-mile time by .39 seconds; increased trap speed by 2.08 mph. Runs were a year apart, but at the same track with the same temps (about 40 degrees).
HKS exhaust -- I can't compare it to stock (out of 60K miles I've put on SE-Rs, only about 400 have been bone stock :), but I can compare it to the Stillen muffler. The HKS (cat-back, of course) lowered 1/4-mile time by a tenth; increased trap speed by .79 mph. Again, both runs were at the same track. Not sure of the temps, but they were probably similar (April vs. Sept.), if not, a bit *warmer* on the run with the HKS. Very noticeable top-end improvement.

--------------------------------------------------------------------------------

Justin Choi Writes:

I had a custom cold air intake made for my 92 Nissan SE-R a while ago and got my hands on a Techtom to test it out. The Techtom allowed me to measure the voltage at the Mass Air Flow sensor. Voltage readings at the MAF (Mass Air Flow) Sensor are used by the ECU to find out how much air is coming through the intake. The ECU then adjusts the fuel accordingly. Honda's don't have a MAF but use a different reading to do the same thing. I believe it's the manifold pressure. The more air I get, the higher the voltage reading I should receive on the MAF.

TESTING:

The cars that we used for testing were a 92 SE-R with headers and 2 inch exhaust and a 94 SE-R with headers and 2 inch exhaust. Although the testing was done on Nissan cars, the same principals apply to Hondas. Instead of testing the cold air system against a stock intake, we gave it a real test by testing it against the proven Jim Wolf Technology POP Charger system. The POP charger utilizes a large K&N cone filter with a 7 inch base and nice billet velocity stack.

The Techtom allows testing of the car out on the road in real-world conditions. There are some issues regarding Dyno-testing of cold air systems since the car is stationary. This makes underhood temps higher than normal and may skew the results in favor of the cold air systems.

RESULTS:

Stationary (no-load, zero MPH) Outside Temp ~ 75 degrees

94 SE-R with JWT POP Charger: 4.34
92 SE-R with Akimoto Funnel Ram II filter with dryer hose bringing in outside air: 4.28
Red Line up to Third Gear (Approx. 95-98 MPH) Outside Temp ~ 75 degrees

94 SE-R with JWT POP Charger: 4.34
92 SE-R with Akimoto Funnel Ram II filter with dryer hose bringing in outside air: 4.28
Stationary (no-load, zero MPH) Outside Temp ~ 87 degrees

94 SE-R with JWT POP Charger: 4.34
92 SE-R with Akimoto Funnel Ram II filter connected to the cold air intake pipe: 4.34
Red Line up to Second Gear (Approx. 65MPH) Outside Temp ~ 87 degrees

92 SE-R with Akimoto Funnel Ram II filter connected to the cold air intake pipe: 4.45
92 SE-R with new K&N filter connected to the cold air intake pipe: 4.47
Needless to say, a huge difference!

The Project 200SX SE-R in Sport Compact got the same intake done at the same place (Place Racing in Covina) and he dynoed it at an 8 horsepower increase. Mike Kojima, the writer and owner of the 200SX SE-R concluded that it was the best bang-for-the-buck item available. He got an average of 5-6 horsepower at every RPM above 3000 over his old JWT Intake with no loss of HP under 3000.

DISADVANTAGES:- Pomanjkljivosti in stranski učinki

Having the filter in the bumper area can make installing cold air setups a pain in comparison to a standard air intake system. Also, if you hit a flooded street you'll end up ruining your motor. I do know of one case where that did happen and it was in "sunny" Southern California during our one week rainy season. However, most of those with cold air intakes drive in the rain and hit puddles with no problems at all and many setups can be changed to allow the filter to sit in the engine bay. Also, a cold air system involves more piping and this means that your intake will be very loud under heavy throttle, louder than it would be with a standard intake. It's a nice deep growl so to most, it's an advantage, not a disadvantage. [Editoral note: So far with this year's rain in CA, we haven't heard of any problems from hydro lock. Several people hit some large puddles but didn't have any problems.]

CONCLUSIONS:- Zaključek

The recent Sport Compact Car article on intakes tries to leave the impression that their tests aren't 100% conclusive. Well, they have advertisers to worry about and aren't willing to make a definitive recommendation. From my personal experience on many different Hondas and Nissans, I can tell you without a doubt that the cold air setups offer more horsepower than standard K&N and intake stack setups on most cars. I have also seen many cases where horsepower was lost after the addition of a standard underhood air intake system. I've tried various home-made setups that bring in cold air through plastic pipes or dryer hoses and none of these have tested to show any improvement whatsoever. A major portion of the gain is from extended the pipe length of your intake and those home-made setups don't provide that. Get some setup, either from the aftermarket or whatever home-made concoction you can come up with, to extend your intake pipe and get your filter away from the heat of the engine but not too close to the ground and you should be in good shape.


--------------------------------------------------------------------------------

Justin Choi Writes:

As far as the other filters are concerned:

I've tried the:

Akimoto Funnel Ram II with velocity stack
Weapon R foam filter
Weapon R foam filter with velocity stack
Baby K&N
Medium K&N
Large K&N
JWT Pop Charger
I only have SOTP [Editor: that's Seat Of The Pants] impressions for most of them. Obviously, I like the JWT setup the best. I wish I had something objective to contribute to the list other than the fact that I don't think it's worth the time or the effort to try the foam filter. It didn't make any SOTP difference and I did a lot of research and found that:

Banzai claims that foam doesn't flow as good as a gauze filter but they flow better than K&N when dirty.

HKS claims that their filter just flows better.

K&N claims that the gauze flows better and especially flows better when dirty.

I've heard stories of people getting little bits of foam in the engine with the foam filters (Dynamic Autosports). John at Hotshot told me of a story where the plastic funnel of the Akimoto Funnel Ram broke off during full throttle operation and jammed itself in the throttle body causing a major accident. JG had an Integra that wasn't producing as much on the Dyno as it should have. They removed the K&N filter and the dyno showed a 5-7 horsepower increase. Then, they added the Unifilter (foam) and got another 2 horsepower! So they say! This was on an Integra with headwork, cams, and all the bolt-ons. John at Hotshot swears by the foam filters. The foam filters are hard as hell to oil since they don't seem to absorb the filter oil very well. (John at Hotshot did tell me to oil it).

The bottom line is that the K&N is considered numero uno by majority of the people out there. Why not go with #1?



VIR: http://www.se-r.net
Slika on the 6th day god created CA18DET Slika
Slika

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Drifter112
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Odgovor Napisal/-a Drifter112 » 10 Dec 2006, 17:51

SR20DE vs SR20DET

There are several versions of both the SR20DE and the SR20DET (Remember 'T' is for Turbo).
While the engines are similar in most respects there are several differences.

Mike Kojima commented:

Here are the differences between the DET and the DE:

The DET has oil squirter piston coolers
The DET has a bigger oil pump.
The DET has a different front pulley.
The DET has lower compression pistons (8.3:1 vs 9.5:1).
The DET has bigger injectors.
The DET has direct ignition.
The DET has a variable intake cam, runs retarded at idle, advanced mid range and retarded top end.
The DET has mechanical shim in bucket type lifters with a slightly bigger in duration exhaust cam.

The GTi-R DET has individual Throttle body injection.
The GTi-R DET has stronger main cap bolts.
The GTi-R DET has beefier rods.

Just about all the parts between a DET and a DE interchange.
Slika on the 6th day god created CA18DET Slika
Slika

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Symon
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Odgovor Napisal/-a Symon » 12 Jan 2007, 19:54

Choosing the right spark plug for the SR20
There is a lot of controversy among Nissan enthusiasts over the best sparkplug for the SR20. Below are the findings of our testing so far.

Sparkplugs come in many heat ranges so the plug can be matched to the type of use an engine receives. For low speed, short hop driving, the plugs electrodes must stay hot enough to burn away carbon deposits, so a hot plug is needed. For high speed racing at high rpm, a hot plug can glow like a diesel glowplug causing pre-ignition and detonation. To prevent this a cold heat range plug is needed. But in low speed driving, a cold plug can fuold with carbon and become useless.

A plug's heat range is determined by the length of the insulator of the center electrode. If the porcelain insulator is short, it is a cold plug. If it is long and extends deeply into the steel shell of the plug, it is a hot plug. A cold plug's short center electrode has a short path to conduct heat out of the electrode. A hotter plug has a longer path and dissipates heat more slowly.

Most import performance buffs seem to be unaware of matching the sparkplug's heat range to the type of driving that they do.

In our experience, the best spark plugs for the SR20DE are the stock Genuine Nissan NGK platinum plugs. Most SR20DE engines, even the stock ones, to run the prefer the PFR6B-11 spark plug. This is the middle heat range for the factory available NGK plugs. SR20-powered cars come with PFR5B-11 plugs which are one heat range warmer. The PFR6B-11 works well on high compression, turbocharged or nitrous oxide powered cars. For running extreme boost (consistently more than 15 psi), a big shot of nitrous oxide (more than 100 hp) or really high compression (more than 11:1) the cold PFR7B-11 plug is necessary. This plug will be on the edge of fouling during regular day-to-day driving, though, so it can be considered a race only plug.

The SR20 has a shallow included angle of the combustion chamber. This makes for a quick burning, detonation resistant chamber. We have also found that shallow included angle chambers typically do not like extended tip plugs. The theory behind extended tip plugs is that the electrode is in a more turbulent section of the combustion chamber, which helps prevent fouling. In the SR20, an extended tip plug puts the electrode too close to the piston dome, screwing up flame propagation, and losing power.

The two main things to remember with SR20s is that the plug's tip length must be close to the stock plug's or power loss will result, and the heat range must be appropriate for the intended use or detonation may occur.

Vir: http://www.se-r.net

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Symon
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Odgovor Napisal/-a Symon » 12 Jan 2007, 20:39

Sport Compact Car - July '97
Project 200SX SE-R

by Mike Kojima


Slika

Part II: The process of making more power with an OBD-II equipped engine.

PHOTOGRAPHY: Les Bidrawn, Dave Coleman, Scott, Dahlquist, Mike Stute


As you will recall, in the June 97' issue we tackled the suspension and braking system on Project 200SX SE-R. So far, these mods are working well, but there is still some fine tuning to be done with brake bias and anti-roll bar pre-loading. These issues will be covered as soon as the car is tuned to our satification. Meanwhile, the vast leaps forward in handling and braking prowess have left us yearning for more power.

Building an engine that has some power while passing undected through California's roadside smog machines is a challenge. Add to this making power without triggering OBD-II. Doing both these things takes thorough planning, not to mention a healthy amount of trial and error. Some horsepower has to be sacrificed to keep the electronic eyes happy but luckly not much. If you want an 11 second machine that you might be able to drive on the street for a while before you get caught (and you will get caught), this article won’t be for you. If you are a regular guy that can’t afford both a street car and a race car, then read on.

First off, extreme modifications is out. Super high-compression, hugely ported heads, large duration/overlap cams and other extremes will all trigger the OBD-II system. Turbos and other forced-induction devices can be done but tons of money and an expert in fuel and ignition mapping must be called in. Reasonable camshafts, mild porting, a properly done header and exhaust, air intakes and NOS are well within the realm of OBD-II passable modifcations, if the work is handled correctly.


Baseline
Project 200SX SE-R was first baseline dynotested on the Bosch chassis dynamometer of Dan Paramore Racing. The Bosch dyno measures driveline drag and an attempt to convert measured drive-wheel horsepower to flywheel horsepower. The result was 137 hp at 6700 rpm with a redline of 7000 rpm. Nissan rates this engine at 140 hp at 6400 rpm, so it seems as if the Bosch technique for finding corrected flywheel horsepower is accurate. Our stock 200SX SE-R felt reasonably peppy but the rev limiter seemed to kick in before the right shift point was reached and the car seem more anemic than the earlier Sentra SE-R, despite the fact they have the same rated horsepower.

After baseline-testing the engine we added some relatively inexpensive bolt-on mods that are condsidered to be compatible with the 200SX’s OBD-II system.


Header - izpušni kolektor
The 200SX SE-R's stock exhaust manifold is made of thick cast iron or covered with insulated heat shields for a reason. Catalytic converters need to be hot to work. Very hot. The thin walls of conventional tubular headers can conduct enough heat away from the exhaust stream to delay catalytic converter light-off. This can greatly increase the amount of time it takes for the cat to start working from a cold start, the point where modern cars make the most pollution. If a lot of heat is lost, even the oxygen sensor’s operation can be affected. Oxygen sensors also need to be hot to operate correctly. A cold, sluggish O2 sensor causes all kinds of drivabilty problems. Some cars arrive stock from the factory with tubular headers but many of them use close-coupled cats because of the heat loss. The close-coupled cats can offset the amount of gain that the headers provide by disrupting the acoustic tuning. As you can see, headers on a modern OBD-II equipped car are not so simple. Any offsets in cat outputs, activation time or O2 sensor operation will trigger error codes.

Slika
Just to prove that our engine modifcations are running clean, the inside of our new GReddy exhaust has stayed clean and soot-free even after more than 1500 miles of hard street driving.

Exhaust Tech provided a custom header designed to work with the Nissan OBD-II system. Nissans OBD-II system uses two oxygen sensors, one controls closed loop operation (when O2 sensor readings are used to automatically adjust the air- fuel ratio under light cruise conditions) and the other is used to gauge catalytic converter effectiveness and light off time. With this electronic watchdog, it was deemed important to try to conserve the heat in the header to help the cat warm up quickly so the computer would continue thinking all is well. Thick-walled tubing was used in the base followed with a coating of plasma sprayed aluminum. This prevented heat from radiating out of the headers pipes and kept the cat at normal operating temperature.

The size and locations of the O2 sensor port and the EGR port were also critical. The location of the O2 sensor fitting was picked to be the same distance from the exhaust port as it was in the original manifold in an effort to maintain proper O2 sensor temperature. Care was taken to make sure that the EGR valves orifice was the same size (8mm) as on the stock manifold and in the same location to prevent the EGR valve from prematurely opening due to back pressure.
Slika
Primary tube diameter and length were important considerations in designing a header for the SE-R, just as with any car, but we also had to deal with O2 sensor location and EGR port placement. The O2 sensor is clearly visible on the number 3 primary tube. The EGR port is located on the number 4 primary under the black box.

The headers primary tube length was tuned to resonate at about 6000rpm, and a larger-than-typical, 1 5/8" diameter to provide enough flow for the 2000cc engine. The relatively low resonance point was placed between the horsepower and torque peaks. The reasonance point, combined with the tri-y design, was chosen to provide the broadest possible power band and to be less sensitive to cam and induction changes that we plan to experiment with later. A tri-y header may be down a few peak ponies from a full race 4-into-1 design, but on a street motor the broader powerband of the tri-y is usually better. The primary tube dimensions were determined through computer modeling. The final dimensions were compromised somewhat to ease installation, make the part easier to produce and to compensate for future cam changes. Since street cars must most always compromise their design to be able to fit in a production chassis, (often totally equal length primary's are not practical), tri-y’s usually come out on top again due to their relative insensitivity to minor tuning variables.



Catalytic Converter - katalizator
The catalytic converter and the rear O2 sensor were retained for obvious reasons. Most modern monolithic matrix catalytic converters are pretty free flowing. Cats got their reputation as power eaters when they first appeared. Those early cats forced the exhaust to flow through a bed off pellets, creating a lot of back pressure. Modern cats use a ceramic honeycomb with straight through holes which add very little backpressure to the exhaust system. Before deciding to stick with the stock cat, we tested it for backpressure. During testing the cat only added a maximum of .5 PSI of backpressure, and under most conditions the cats effect was too low to measure. The difference between different brands of performance mufflers was greater than that! The lesson here is to leave that cat alone. Unless you are trying to double your horsepower with a turbo or your cat is greatly undersized from the factory, there is little to be gained by tinkering with it.



Exhaust system - izpušni sistem
In our testing, the GReddy cat-back exhaust system was selected because it has the least amount of backpressure (2.5 PSI with cat, others had as much as six PSI) and was also among the quietest. The GReddy unit has a pleasant, deep, medium-loud-tone with little irritating high frequency resonance. The GReddy system is also very high-quality, constructed of mandrel-bent 60mm stainless steel with a polished muffler and a 130mm tip. The large shiny tip doesn’t exactly fit into our sleeper theme but it sure looks good. Big shiny tip or not, GReddy also has the advantage of actually certifying their exhaust systems to the stringent standards of the California Highway Patrol. There are no federal or state standards for noise on aftermarkit exhaust systems so the CHP standard was the toughest GReddy could find. GReddy can send you a certificate of compliance to the standard if you ask. Just the thing to give to the officer if you get pulled over for an apparent violation. If the officer still insists on giving you a ticket, you can always go to court with your certificate in hand.



Air intake - sesalni del
A Jim Wolf Technologies POP charger was used to replace the stock airbox and air filter. The POP charger uses a cone-type open filter element with an additional cone of air filter material mounted in the front cap of the air filter element. This cone adds filter area, reducing the pressure drop needed to pull air throught the filter. The filter clamps to a machined aluminum velocity stack that bolts to the airflow meter. The Nissan airflow meter is designed to be accurate under laminar flow conditions. A sharp entry into the meter can cause the meter to read inaccurately, leading to inapproiate fueling and lost power. The fact that the stock air filter box incorporates a small velocity stack is a hint at what a good idea a velocity is on this particular engine. The POP charger is a high quality unit overall, and it carries a CARB OE number making it legal in all fifty states.



ECU - računalnik
For engine modifications, Nissans have a big advantage over many other sports compact cars. Since Nissan’s ECU fuel and spark tables are driven by the airflow meter output, the ECU can automatically compensate for changes in volumetric efficiency unlike the speed density systems on Hondas. In otherwords, mild camshafts, headers and head work can be used without automatically causing the engine to lean out. The greater the airflow the more fuel the computer will inject up to the limit of the airflow meter voltage curve or injector capacity. Even with this inherit advantage, there are still comprises in the stock ECU programming. The stock ECU is tuned to be able to run on bad gas, and to maintain drivability and clean emissions even with poor maintaince. Since this car is well cared for and feed a diet of high octane-fuel, there is room for improvement.
Slika
With a very careful selection of components, we were able to find an honest 29-hp gain without sacrificing horsepower anywhere, and without triggering any OBDII trouble codes!

For this improvement, we turned to Jim Wolf Technologies. The Wolf ECU works best with the timing set at the factory maximum of 17 degrees BTDC. Advancing the timing more than this will cause a loss of power, especially on the top end. The Wolf ECU modifies the fuel and spark maps for optimal performance while maintaining OBD-II compatibility. Wolf removes the top-speed-limit fuel cut function from the program. Wolf also raises the stock rev limit of 7000 rpm to 7700 rpm, which was a big help because we were continually bouncing off the factory rev limiter with the stock ECU.

The Wolf ECU also limits the amount of high temperature and or knock sensor response retard. This is an area where Wolf's years of experience in racing shows. Wolf discovered that the SR20DE's stock tuning is overly sensitive to knock. Normally, when the knock sensor recognizes the onset of detonation, the ECU will retard ignition timing to prevent further detonation. Unfortunately, retarted ignition timing also tends to increase coolant temperature, which, in turn, increases the tendency knock, which causes the ECU to further retard timing, etc. In the end, coolant temperature soars and power output suffers. Though the conditions needed to start this thermal overrun are rare for the average Joe, aggressive driving can bring coolant temperature into the range where this will happen frequently. The reduced ignition retard response of the Wolf ECU prevents this vicious cycle from starting in the first place.

These extensive program modifications are no small task considering that the vehicles engine control processor talks to the OBD-II monitoring processor. Any disagreement between the two results in error codes and headaches.

The Wolf ECU made a very noticeable difference with improved throttle response and greater top end power. Best of all no check engine lights appeared indicating zero error codes. Because of the advanced ignition timing and reduced knock sensor retard, the Wolf ECU requires the use of 92 octane gas, but if you want the most power out of the stock engine, 92 octane is a must anyway. Wolf also has ECU’s available for almost all Nissans and Infinities, some of which have CARB OE numbers.



Camshafts - odmične
Perhaps the most difficult part of Project 200SX SE-Râ€

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Shiner
Cipa rider
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Odgovor Napisal/-a Shiner » 13 Jan 2007, 01:04

fuck kok je tega :roll:

d best :zakon:
powered by Nissan Silvia S14, allways under construction :slarti:
https://www.generaliclub.si

Jankoh
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Odgovor Napisal/-a Jankoh » 13 Jan 2007, 10:18

No naj dodam samo to. Mike Kojima je tisti kateremu se lahko verjame ko govori o tem kaj je treba nareti.
Performance and response are not coincidence.

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Symon
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Odgovor Napisal/-a Symon » 13 Jan 2007, 14:16

Se popolnoma strinjam! :zakon: :bow:
Na vseh Nissan tuning straneh se pojavlja, pa ne le to, tudi v Sport Compact Magazine, in njeni knjigi (ki jo imam doma). Če se ne motim je nek ing. tako, da ve kaj dela. In kaj govori. (da je SR20 eden najboljših motorjev na svetu, da je narejen močneje kot B16 :twisted: )
Skratka, če kdo kaj išče po netu in naleti na njegovo mnenje, naj ga upošteva.

Kje boste najverjetneje naleteli nanj:
http://www.se-r.net/index.php
http://www.sentra.net/
http://www.nissanforums.com/
http://www.sportcompactcarweb.com/
http://www.nissanperformancemag.com/

In mimogrede vse te strani so odličen resource za iskanje vse kar želite o tunanju vaših Nissanov. :wrum: :nissan:

EDIT: Jankoh, hvala za opozorilo. :oops:
Nazadnje spremenil Symon, dne 15 Jan 2007, 10:23, skupaj popravljeno 2 krat.

Jankoh
Primera GT driver
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Odgovor Napisal/-a Jankoh » 13 Jan 2007, 18:35

Pa ne samo to midva sva že kakih 5 let na vezi. Še iz sentra.net-a. Pa naj rečem da ko se mi je kje stavlo in sem popvprašal Mike-a je stavr vedno šla naprej. Zadnje čase pa se je det kar umknil iz forumov. No kot tudi večina ljudi iz tistih časov (dobrih časov) :).
Performance and response are not coincidence.

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Symon
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Odgovor Napisal/-a Symon » 13 Jan 2007, 22:07

Potem pa samo :bow: Daj povej mu, da ima tuki v eni majhni Sloveniji enega oboževalca, ko bosta naslednjič na vezi! 8)

Jankoh
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Odgovor Napisal/-a Jankoh » 14 Jan 2007, 11:07

Performance and response are not coincidence.

Freak
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Odgovor Napisal/-a Freak » 30 Jan 2007, 19:03

U matr,a lahko tole v slovenscini prosim :)

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Symon
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Odgovor Napisal/-a Symon » 30 Jan 2007, 20:08

Za vse, ki vas zanima kateri SR20 motor točno imate v svojih Nissanih!
This new thread has been carried over from:
http://www.sr20forum.com/showthread.php?t=132558



This is a post for pople trying to identify what engine they have...
Lets keep this to ONE POST PER PERSON UNLESS YOU NEED TO ADD SOMETHING. Make sure to include your USDM motors also. Also Inclued other markings on the head like 5R 1R 3L and such Tell alittle about your engine so we can get a list of what to look for in 10:1's and so on.. Pictures would be great also! Turbos will be added soon This list will be updated often!!!!

Head #'s
1N5 V1 - SR16VE
1N5 V2 - SR20VE
5J -
51N -
52F - Larger Exhaust Valves Silvia engine
53C - JDM Pulsar GTi-R. 8.3:1 T28 Turbo Low Imp. 444cc Injectors Larger Top Mount Intercooler Larger Oil Cooler Solid Lifters Ind. TB's Oil Squirters
53J 2L- Flat Pistons, highport, egrless and gold/black Valve cover (*)
53J 2R - Normal pistons, highport, egrless and gold/black Valve cover
53J 7R. Gold Valve cover with black strip down middle, egr-less, tubulor exhaust, highport
53J V1 - USDM Black Channel Valve Cover Highport 9.5:1 1990-92 Red Injectors EGR OBD-1
53J V2 - 1R USDM Silver Valve Cover Highport 9.5:1 Red Injectors EGR OBD-1 1993 RIBS
53J V3 - 5R JDM Ribs on head Silver Valve Cover Red Injectors Mitsubu Alt. tubular ex. manifold 1/1 in circle and /5 in circle on head beside 53J
53J V4 - JDM Black Channel valve cover
53J V5 - JDM Silver Valve Cover No Ribs
53J V6 - BlueBird SR20DET 8.5:1 sodium filled valves 7mm stem Oil Squirters T25 Turbo High Imp. 370cc Injectors Top Mount Intercooler Oil Cooler Hydraulic Lifters Single TB
53J V7 - JDM Black Channel valve cover tubular ex. manifold 10:1
53J V8 - 2L W11 Avenir 8.5:1 silver valve cover Ribs 370cc purple injectors T25 ball bearing turbo Big TPS No EGR Mitsu altenator High port Internal coil OBD-I Stock oil catch can steel pipe has a built in restrictor.........the one the runs from the valve cover forward then behind the distributor to the stock catch can. same BOV/CBV as teh 1stGen DSM
53J V9 - W10 weaker BOV then the W11 Non ball bearing turbo 8.5:1
53J V10 - 3L 10:1 JDM bare aluminum cover w/ black in the middle No Ribs under the coil there is a circle with a line through it and a small number 7
53J V11 - 2R I think this is a W10 BlueBird SR20DET 8.5:1 sodium filled valves 7mm stem Oil Squirters T25 Turbo High Imp. 370cc Injectors Top Mount Intercooler Oil Cooler Hydraulic Lifters Single TB Red V/C black channel
53J V12 - 3L JDM Ribbed head, All silver valve cover, either a 6 or 9 and a 1 in circles under the coil.
53J V13 - 8R JDM with an 8 in a circle behind the coil bare aluminum vc tubular header external coil and egrless of course highport ribs on the side of head
53J V14 - 8L USDM Ribs 93 NX2000 All Silver Valve cover 9.5:1
54C - N14 Pulsar DET
54D -
58Y - SR18DE JDM highport.
64J - SR18DE SR18Di JDM lowport.
65J - 2R 2J2 10:1 JDM Silver valve cover
78E - BlueBird SR20DET (53J Head) Larger Exhaust Valves
79E - Larger Exhaust Valves
89H - SR20DE Silver Valve Cover U.K. '94 SLX P10 lowport No ribs 10.0:1.
89J - SR20DE Red Valve Cover UK lowport sodium filled valves 10:1 Gray 259cc Injectors .
94Y V1 - 3L SR20DE US lowport 9.5:1 OBD-1 1994
94Y V2 - SR20DE US lowport 9.5:1 OBD-2 1995-99
96J - 1R UK Redtop 10:1 Highport (UK 101 1R 96J head)Gray 259cc Injectors Mitsubu Alt. sodium filled valves
Unknown - USDM B15 Roller Motor Nonpainted VC 9.5:1 OBD-2
Unknown V1 - AUTECH 11.5:1 175hp for Lucino Nonpainted VC
Unknown V2 - AUTECH 11.5:1 180hp for Primera Nonpainted VC
Unknown - 53J 4R, JDM 53J 3L, 53J 1R McRib USDM, 53J 4J???, 53J 4L




Cars With 10:1's or higher

Nissan 100Nx GTi
Nissan Sunny GTi
Nissan Almera 2.0 GTi
Nissan Almera Tino 2.0
Primera HNP11
Primera 2.0e HP10
Primera 2.0eGT (5 door) FHP10
Primera 2.0GT FHP11
Primera 2.0Te HP11
Primera 2.0T4 HNP10
Primera Wagon WHNP11
Nissan Primera Wagon 2.0 WHP11
Prairie Liberty GF-PNM12
Autech Sunny Lucino Version B13
Autech Lucino Version 3 door N14
Autech Pulsar SERIE Version N14
Pulsar GTi Autech version N14
Autech Primera 2.0e HP10
Tommy Kaira ZZ-S
Tommy Kaira ZZ
Nissan Avenir GF-PW11
Nissan PRESEA 1.8L R11
VIR:http://www.sr20forum.com/showthread.php?t=132608

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Symon
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Odgovor Napisal/-a Symon » 15 Apr 2007, 22:36

Vse možne odmične za SR20 motorje.
http://web.utk.edu/~cjohns32/camlist.htm :bow:
(edino nikjer spet ne piše, da bi bile redtop kaj hujše)

The best valve jobs are called multi angle valve jobs with three or more distinct angles. The main angles are the throat cut, which is a 60-70 degree cut that blends the port wall to the seating cut. The seating cut is a 45 degree cut which is the sealing surface for the valve. This critical cut should be 0.040-0.060 wide for a multi valve engine like an SR20. Finally there is the top cut which is a 30 degree cut which blends the seating cut to the combustion chamber. The purpose of these cuts is to help the air flow smoothly around the valve, especially when the valve is starting to open or close.

Another valve job trick is to place a 30 degree back cut above the 45 degree seating cut on the valve itself. This helps the air get around the valve better especially at low lifts. A five angle valve job uses two extra cuts to make the transition even smoother. The best valve jobs are radius valve jobs which are a 3 or 5 angle valve job which is hand blended after cutting for a perfectly smooth transition. The quality of a valve job is very important because it can contribute up to 50% of the flow gains that headwork will get you.

The best valve jobs are done on a Serdi machine. The Serdi is very high precision which insures that all the valve angles and depths come out equal. Most low price shops use stones. Stones can give a good valve job but the stones must be dressed frequently and dial indicators must be used to insure that the seating surface remains concentric. Stones require a highly skilled person who is conscientious of doing a good job. A butcher can make a big mess with stones.

Unshrouding the valves is an operation where the edge of the combustion chamber is cut back by about 25% of the valve diameter so that the wall of the combustion chamber does not block the air going past the valve into the cylinder.

Polishing the combustion chamber removes sharp edges that can glow red hot and trigger detonation. It also makes it harder for carbon to stick. Polishing should be limited to the combustion chamber and exhaust port. The intake port should be no smoother than 220 grit as maintaining some boundary layer turbulence is good for good bottom end. This turbulence makes the port virtually a little smaller at low flow velocities.

Personally, my belief is that the best head porters for the SR20 head are (Dan Paramore Racing), JWT and B.C. Gerolomy. My own personnel heads are done by DPR and Nissan Motorsports uses B.C. Gerolomy. JWT requires no further introduction here!

Beware of bad headwork. Perhaps the most famous Honda builder who advertises very heavily and sponsors many 10 and 11 second Hondas does awful commercial headwork. I have seen heads from that shop that have huge, lumpy uneven ports. The valve jobs were 1 angle that were cut so deep that the valve would have to rise about 0.040 to get out of the huge crater of a seat cut! Talk about shrouding! The valves were cut so deep that I am sure that the stem tips would have to be faced off to maintain proper valvetrain geometry IF that was done! Perhaps it was the new guy that did these heads but I have seen more than one of them. This shop’s work could not be all bad because of their track record, but I have yet to see a good off-the-shelf head from them. Stuff like this is why many Honda owners complain that their cars end up slower than stock!

My DPR head is a marvel of detail. The head is fully deburred to remove all sharp edges that can cut you during assembly and cause stress risers. Then it was ported by Dan Paramore, keeping an eye for increasing velocity rather than ultimate flow. My objective was to build a torquey engine with no loss of bottom end power. Dan cut down the valve guide bosses where they intrude into the port and smoothed the hydraulic lash adjuster boss where it hangs down into the intake port. This annoying feature was added to the 95 and later low port head.
The valves had the stems turned down for better flow to about 6mm below the valve guide. That way they would block less of the port's cross section area. Dan also reshaped the valves going way beyond the customary 30 degree back cut. Finally Dan swirl polished the valves. Swirl polishing is polishing putting a hurricane looking pattern on the face of the valve. This is supposed to increase flow. The shaping considerably reduced the weight of the valves which should give more rpm headspace before valves float and the classic SR20 rocker arm flies off. To my knowledge DPR is the only company that puts this much detail work into the valves.

The main advantage of the DPR head is Dan’s combustion chamber work. Dan welded up the edges of the chamber to increase the quench. Quench is the area where the piston top comes within 0.040 of the combustion chamber near the edge of the cylinder. The quench zone squishes the fuel air mixture to the center of the cylinder where it can be easily burned. This reduces the likelihood of detonation and increases efficiency. This feature found in all of DPR’s stage 6 heads sets them apart from other tuners and is the reason that I chose them. Increasing quench does raise the compression ratio, so if you are doing pistons and stuff, this must be considered.

The DPR head has a combustion chamber volume of 43cc’s down from the stock volume of 46cc. This raises the CR on stock pistons form 9.5:1 to 10:1. 10:1 is fine on pump gas with the stock or off the shelf JWT ECU. If you are running JWT’s NOS 100 shot ECU the program will have to be changed a little at this CR. If you are running NOS with someone else’s kit, you will have to retard the spark a little under NOS operation. I think around 4 more degrees than you already retard for a 100 shot would be a good starting point although I have not tested that.

If you use the Nissan Motorsports flat top pistons the CR gets close to 11:1. With the planned JWT forged big bore pistons the CR becomes 12:1 which is not streetable but the dome can be machined off to get 11:1. With 300ZX pistons the CR is close to 12:1 but it is easy to machine the domes off of these also. To run 11:1on pump gas requires a special program from JWT. The stock ECU will not work. I do not have much experience with big (100+HP) NOS units and real high compression but you must be careful! More ignition retard and richer fuel mixture are appropriate here. Detonation can result in rapid death! JWT has a 50 shot program for 11:1 available.

My DPR head resulted in a power increase of 10hp above 5000 rpm with no loss of power below that at all! That is testimony to Dan’s skill. The bottom end felt better but the dyno did not register that so I can not claim that. When revving the engine in neutral it was much more responsive to blipping the accelerator pedal. If Dan was to build an all out power head, I feel that their would be another 5 or so hp available at high rpm’s but some low end power would be lost. Dan could have made me some bigger valves but I did not want to pay for that!

The high port classic head (91-93) is superior to the low port head (94-present). The changes to the head were done to improve hydrocarbon emissions. The high port head has long intake ports that bend smoothly around the hydraulic lash adjuster and shoot straight into the cylinder. Unfortunately for pollution's sake this long intake port necessitates having the fuel injectors farther back from the intake valve. This causes the port walls to get wetted with fuel. This fuel is sucked into the engine in-between shifts and on overrun causing the mixture to spike rich.

To eliminate this Nissan went to the current low port design with it’s short intake port and close coupled injectors. Unfortunately the hydraulic lash adjuster must now hang into the intake port obstructing flow. Also the approach angle of the port no longer has such a straight shot into the cylinder either. I believe, although I have not personally tested, that the older high port head is good for about 5-10 more hp than the low port head. To substantiate my theory I have noted that when looking at Japanese Performance magazines, no Japanese tuner uses the low port head in their crazy SR20s.

If anyone has dyno results of a fully developed high port head please submit them to us so we can post them and compare them to project SE-R’s low port head.

As an update, DPR has done some R&D on the high port head and is now able to extract about 25% more flow out of them, up from the 10% increase seen with my head. Dan feels that this could result in 10-12 more hp for his latest creation. Dan has also developed a new valve spring set and new titanium retainers as well as 1 mm oversize stainless valves. George Roffe, Mike Palhs and Ben Benavides have all or some of these latest mods in their motors and we eagerly await dyno results.

Pistons
There are a number of choices here. Nissan Motorsports has the European and Japanese spec pistons that are flat topped (the stockers have a slight dish) that raise the compression to 10:1. This should give about 5 more hp. Nissan Motorsports also has the SR20DET piston which lowers the compression to 8.3:1 for turbo motors. These pistons are available in the standard Nissan size grades in standard bore. This is ok for lower mileage motors but for high mileage motors you might need an oversize piston. Please don’t bother Ron at Nissan Motorsports by asking him if these pistons will work in your motor at xxxxxx miles! Get a FSM and a bore gauge and figure that out for yourself first, then call him! The Nissan Motorsports pistons are cast, but they are a good quality cast piston and can take relatively high amounts of abuse. This means no real high boost levels (much above 14 psi) or huge nitrous hits (certainly not more than 100 hp).

A late model 300ZX VG30DE piston can be used with some modification to the connecting rod. This piston is 87mm up from the stock 86mm which will give you 2045cc. The small end of the connecting rod must be ground down by 0.010 on either side to give the rod enough running clearance. I did it on a belt sander being careful to mike the rod several times along the way. Be sure to put a slight chamfer on the pin bushing after you are done. I used a deburring tool and polished the edge with some 400 grit wet dry paper and some honing oil.
The VG30DE piston will give you 11:1 on a stock type combustion chamber. On a DPR stage 6 head you must mill off the dome of the piston. This can be easily done on a lathe or mill by any competent automotive machine shop. Mill the dome completely off making a flat top piston. The VG30 DE piston is a high quality cast piston.

JWT will soon release a forged 87mm piston. It will have a slight dome to give 11:1 with a stock configuration head. The dome could be removed for a lower compression. Forged pistons are much tougher and can withstand detonation and stress much better than a cast piston. The JWT piston will use a high silicon alloy which allows tight piston to wall clearances and also has a super strong, lightweight tool steel piston pin.

You might be wondering if forged or cast pistons are better. Cast pistons are made by pouring molten aluminum into a mold. Nissan cast pistons are pressure die cast in an inert gas atmosphere. Pressure casting results in a stronger, denser part with less inclusions than the low tech pour in the mold method. A genuine Nissan cast piston is dimensionally more stable than a forged piston and can run extremely tight piston to wall clearances, as little as 0.0004"! Tight piston to wall clearances help with oil consumption issues, hydrocarbon emissions and piston ring life. The bad thing is that cast pistons are more brittle and tend to crack ring lands under detonation.
Typically the number two ring land cracks on Nissan pistons. Under lots of detonation, nitrous or boost, the pin boss of the cast pistons can crack also. Usually this incident claims everything south of the intake manifold! Granted Nissan cast pistons are a high quality, strong cast piston and most list members, even you hard core ones will not get to this point.

Forged pistons are made by smashing a heated billet of aluminum into a forming die with extreme force. This results in an compressed microstructure with good grain flow in critical areas such as the pin boss. Forging alloys are also ductile and strong in nature. Forged pistons offer superior strength and toughness resisting fatigue and cracking. Forged pistons can be made thinner and lighter due to their superior strength. Forged pistons can take detonation much better than cast pistons.

Forged pistons can also handle the strain of high boost and Nitrous. All racing pistons to my knowledge are forged. The disadvantages of a forged piston are that it must run a larger piston to wall clearance than a cast piston. This is due to two reasons. The first is that forging alloys grow more with heat, the second is because of the violent nature of forging; a forged piston has more internal stress and is not as dimensionally stable.

Old school forged pistons needed to run as much as 0.009" piston to wall clearance. These pistons sound like a diesel engine, rattling like crazy. Due to recent advances in piston alloys and skirt design, modern forged pistons can be run as tight as 0.006-0.003".
Pistons that run on the high side of this scale will still rattle. Ones on the low side can be fairly quiet. Usually this has to do with the silicon content of the alloy. Low silicon pistons are the ultimate in strength and toughness but require big clearance because of the metal’s high expansion rate. These are pistons used in top fuel drag racers or the real nasty turbo Hondas. High silicon pistons run tighter clearances and are slightly less ductile but are still much stronger than cast pistons.

I would not recommend a low silicon piston for street use no matter what. It would be noisy, wear rings quickly and be a oil burner after not so many miles.

JWT pistons will be high silicon and can be run at 0.003". The are almost as quiet as stock pistons. If the skirts are coated with a dry film lube like Swaintech poly moly, bringing the clearances down to 0.0015 or so, they should be as quiet as stockers.

If you are going to push the edge with turbo boost, nitrous or are going to do some real racing, forged pistons are the way to go.
By going to 11:1 CR with pistons, my engine gained at least 10 hp across the board, from off idle to the fuel cut. High compression was one of the best all around mods so far. High compression increases thermal efficiency and lowers the BSFE (Brake Specific Fuel Consumption). My car gets a consistent 29-33 mpg despite spirited driving. As I have stated before, a JWT ECU is mandatory with 11:1 to prevent engine-destroying detonation regardless of piston type.

I may be trying to build a big gun engine within the next year or so. I will sleeve the block so a 90mm bore will be possible. Forged, slightly dished pistons will be used for an 11.5:1 cr. Then a KA24 crank with a cut down snout and welded up thrust surfaces will be used to bore and stroke the engine to 2400cc. Amazingly the KA24 crank almost drops right into an SR20!

JWT pro-series race cams will be installed. More displacement can mask some of the bad characteristics of big camshafts like lack of low end power and lumpy idle. My goal is 185 wheel or 215 crank hp with even more low end torque

Crank, Rods, Bearings, Machining, Balancing, Coatings, Manifolds, etc.
The SR20 is blessed with a near bulletproof bottom end. The crank and rods are forged steel unlike the typical cast iron that most American motors run. The rod bolts are a beefy 9mm. The crank features rolled fillets, an uncommon strengthening operation used usually only for racing or heavy duty parts. The rod bolt registers are spot faced, leaving a generous amount of metal around the bolt holes, a traditional weak area in connecting rods.

Both the crank and rods are subjected to a severe shotpeening from the factory. Shotpeening microforges the surface of the part making it stronger and harder while leaving the interior soft and ductile. This step can improve the fatigue strength of a part by over 100% and is usually reserved for high end racing parts. The main caps are tied together with a stiff aluminum girdle which improves bottom end rigidity significantly. This feature is usually found in all out race motors. These design elements produce an engine that is nearly bulletproof. I have seen motors with over 100,000 miles on them with the factory honing marks still visible in the cylinder bores! The number of list members in the 100,000 Mile Club is a testament to the durability of the SR20.

The only catastrophic engine failures that I know of (Tom Paule and Zak Nilsson) were the result of low oil levels with spun bearings. Chuck Nibbana’s super trick engine also mysteriously disassembled itself but that might have been because of improper clearancing. I have screwed up 3 SR20’s myself but that was the result of not watching the temperature gauge while racing IMSA and SCCA. Gross overheating was an understatement. Clark Steppler of JWT has never seen a catastrophic failure that could be traced to the engines fault, either.

The same bottom end of our US model SR20DE also is used for the turbo SR20DET so we have a lot of headspace before we start to challenge the strength of the bottom end. The stock parts can be used until the hp climbs well into the 200’s. So bring on the NOS, turbo boost and compression! We have run Ryan Besterwich's turbo car (formerly Searl's) as high as 20 psi of boost which pushed the car into the low 12's with a completely stock bottom end with no harm. His car has over 80k miles on it and is still going strong. I estimate that his car is putting out over 400 hp with the stock bottom end! If detonation can be controlled the stock bottom end is pretty strong!
If you are building a hot street SR20, I recommend leaving the rods alone. By doing the traditional beam polishing you will be removing the factory tough shotpeened surface. If you reshotpeen the rods after polishing they will have to be resized and straitened as proper shotpeening distorts the parts. It is not likely that a local shotpeener can do as good of a job as the factory either. The same goes for the crank. It won’t hurt to do these traditional race prep steps but it is probably not worth the effort on the SR20.

If you do prep and re-shotpeen your rods make sure that the piston wall oil squirter hole does not get blocked or peened over. This hole sprays oil on the thrust side of the cylinder helping with lubrication and keeping the engine quiet.

In fact, I might say that no matter what you do to build a naturally aspirated motor, if you keep an 8000 rpm or less redline, you don’t need special rods.

I do not have any personal experience with the well-publicized-by-Turbo-magazine, Metalax treatment process but have heard good things about them. I do have plenty of good personnel experience with shotpeening solving many parts breakage problems. Recently I have had very good luck with cryogenic treatment preventing breakage of drivetrain parts with high powered SE-Rs and I am currently building a VG30DE motor using cryogenic treating extensively.

For extreme use in killer turbo motors running near 20 psi of boost or for those of you running 100+hp NOS units, racing rods may be in order. JWT can get Crower rods. I believe these rods are machined from 4140 billet. I am using Cunninham rods in another engine. These rods are a little lighter than Crower and seem just as high quality. Carrillo makes excellent rods also but they would be a custom application and take 6-12 weeks for delivery. These racing rods do not have the oil squirter hole in them which could result in slightly shorter life of rings and pistons.

The rods and pistons should be balance to within 1ž2 gram and the crank dynamically balanced. I have found that Nissans are generally within 1 gram from the factory! A typical American car is usually off by as much as 5-12 grams! I like to polish the journal surface of the crank. You can have a local machine shop do it using the lightest grit of polishing paper belt. You don’t want to remove so much material that the crank dimensions change, just reduce the RMS of the surface by knocking off the peaks of the machining marks.

The factory Nissan bearings are strong and durable. I recommend running bearing clearances in the middle of factory spec on a typical street motor. Clearances on an all out racing motor can be set on the looser side of factory. When buying bearings, Clark Steppler of JWT has told me (and I have also observed) that if an engine has any kind of mileage on it, the next tighter bearing size can be used other than the number that is stamped on each journal of the block and crank. Remember to mike and bore gauge all the journals to confirm proper dimensions before assembling. If you don’t have access to these , at least use plastigauge to make sure that you are in the ball park.
When boring or honing a block, it is better to use a torque plate. A torque plate simulates the stress of a cylinder head being bolted on your block. With a block that was machined with a torque plate, the bores will remain straight when the head is bolted on. Usually the block will distort and the cylinders will become out of round accelerating wear and reducing the effectiveness of the ring seal when the head is bolted on. Granted this is a small difference but is important if you want to build a good motor. For this reason the main caps should also be bolted on and torqued when the block is being machined.

Boring and honing should be done on a Sunnan CK10 machine. This is a high precision machining center that makes the honing of a good round bore almost idiot proof. Since today’s low tension rings require a smooth surface to seat properly, plateau honing after the dimensional honing reduces the RMS of the surface for lower friction, better sealing, less oil consumption and longer life. JWT has pioneered the use of plateau honing on the SR20 and has the process figured out for a smooth bore surface that will still allow the rings to seat. When properly machined with a torque plate and plateau honed, it is possible to have an engine that leaks down at 2% or less! [Editor's note: Nissan specifies that up to 10% is acceptable; most SR20DEs leak down at close to 5% (source: senior mechanic at Falore Nissan)]
JWT is the only company in North America to my knowledge that has a torque plate for an SR20 engine. JWT is most likely the best company to machine your SR20 block. JWT can also machine your block for SR20DET piston coolers. Piston coolers are oil jets that squirt oil onto the underside of your piston dome to help lubricate the piston pin and to help keep the piston cool. As aluminum starts to lose strength above 350 degrees, piston coolers can help quiet a bit. The SR20DET uses piston coolers as does the 11:1 cr SR16VVL N-1 spec motor. This Japan market hyper motor makes 200 hp from only 1600cc!

Since Nissan feels that this 11.6:1 motor needs piston coolers it is probably a good idea to put them in yours. The piston coolers have a spring loaded valve so they only open at higher rpms to maintain good oil pressure at idle and in bumper to bumper traffic. In my motor there was a noticeable drop in water temp once the coolers were installed. To my knowledge JWT is the only company that has the fixturing to machine a block for these piston coolers. Talk to Clark Steppler at JWT for machining.

When building a killer motor it is a good idea to replace the main cap bolts with the ones found in the SR20DET. These are about 20% stronger. Nissan Motorsports stocks these.

I am a believer in special coatings. Coatings are great for adding to reliability or to help control factors such as heat so special tolerances can be used. At the advice of Nissan Motorsports I used Swain tech coatings. Unlike the other to-be-named coating houses that use off the shelf coatings, Swain develops their own in-house coatings that are much more sophisticated. Where most other companies have a one layer coating, a Swain coating might have 3-4 different functional layers. I use Swain tech gold thermal barrier coating on my pistons. This is a severe duty 3 layer thermal barrier that reduces heat transfer by about 25%. This helps protect them from detonation and Nitrous abuse. By keeping the heat out of the pistons, I can run an amazingly tight piston to wall clearance of 0.0004 inches. That is 4 ten thousandths of an inch! My engine does not burn oil at all even with water-thin 5w30 Mobil 1 oil.

I also use Swain poly moly (http://www.swaintech.com/store.asp?pid=10319) dry film lubricant piston skirt coating. This coating uses molybdenum disulfide and tungsten disulfide for a dimensionally stable heat conducting matrix. This is better than the teflon that most other companies use because teflon distorts and creeps under load. Teflon is also a heat insulator. Since the pistons cool themselves by conducting heat through the skirts, it is not to good to insulate them. Poly Moly can help tame the clatter of forged pistons. Poly Moly also tightens your piston to wall clearance by 0.0014 or so inches so you may have to compensate in your bore machining for this added clearance.

The guys at Nissan Motorsports tell me that poly moly significantly cuts piston and cylinder wall wear. Next time I go through the motor I will probably coat the valves and combustion chamber to protect them also. One of my friends had a 20 degree drop in water temperature, 300 rpm faster turbo spool, and 300 degree higher EGT's with a fully Swain coated motor. On my hopefully 700 hp Twin Turbo Z motor, I will be using Swain coatings on just about everything from the bearings to the undersides of the pistons. I believe that these coatings are like a cheap insurance policy.

Swain also makes slippery flow improving coatings, heat dissipation coatings, wear resisting coatings and stealth coatings that are not detectable!

List member Kurt Sussman is planning to build, test and manufacture a short runner intake manifold. When running computer simulations with Dynomation’s software, gains of up to 15 hp above 5000 rpm with losses of only 2-3 hp below 3000 were noted. This seems to indicate that Nissan sacrificed lots of top end power to gain a little below when designing the manifold. I noted that Nismo’s race manifold as well as GReddy and JUN’s race manifolds have short runners. The 196hp SR20VVL also has a short runner manifold. As these manifolds are designed for the RWD S13 and S14 chassis, Kurt took it upon himself to design one for the FWD cars. Yeah Kurt! We will be posting the results of this manifold as Kurt get around to it. However, he just had a baby girl which should postpone his manifold development for quite a while. If anyone else wants to do it, let me know

Extrude Honing
Extrude Honing is a process where an abrasive putty is forced through your manifold or other difficult to port areas at a high velocity, removing material. Extrude Honing is great because it can port areas where it is otherwise impossible to do so, like in the middle of your very long runner manifold or deep inside your manifold's plenum chamber. Extrude honing is also very good at equalizing manifold runner flow.

Smaller more restrictive areas in the head act like a venturi so the putty flows faster there. Faster flow equals more cutting action and thus the Extrude Honing process by nature removes material where it's needed the most. This cutting mechanism is very good at producing runners that flow equally.

We tried Extrude Honing the manifold on project SE-R. This is the shorter runner manifold for the low port, post '93 head. The end results were mixed. Although the Extrude Honing performed extremely well on the flow bench, as the folks at Extrude Hone said it would, the dyno tested power increase was minimal.

On the flow bench the Extrude Honed manifold flowed a whopping 15% more than the stock manifold. Runner to runner flow which varied by about 13-14 cfm per runner stock had the variance cut down to less than 1 cfm per runner. With these excellent results we eagerly bolted on the manifold. By a SOTP evaluation, it was thought that the manifold improved throttle response and top end power. When the manifold was dynoed, the results were disappointing as the motor only gained one peak hp while losing one hp below 5000 rpm. Past the power peak until the fuel cut, the motor gained 3-4 hp. Although these gains seem small, they were repeatable through 4 back to back dyno pulls.

This shows that increasing the intake manifold's flow does not help too much even on a fairly modified SR20. Obviously the manifold is not a major choke point in the induction system. On an engine with race cams the gains would be larger as our manifold seemed to do the best at the very top end. Our computer simulation still indicates that a shorter runner manifold will help quite a bit. This is because the shorter runners will resonate at a higher rpm, improving cylinder filling through passive supercharging. This resonance tuning does not rely on pure steady state flow gains like extrude honing does. We are eagerly waiting for Kurt Sussman's short runner manifold, though we may have to wait until his baby graduates from high school!

Since the classic or pre-94 manifolds have longer, more curved runners, they have greater internal scrubbing losses due to the increased surface friction of the longer, deeper boundary layer (the still air near the runner's walls that does not contribute to flow). Perhaps this process would be more beneficial on one of these manifolds.

So in short, if you have an engine with just the easy bolt on parts, the Extrude Hone process most likely will not help much if at all. If your engine is really built with cams, headwork, compression, etc. and you are interested in getting every bit of power, you might consider it, but it would be a finishing touch type of modification.

If you have a killer high revving NA or high boosting turbo motor it might definitely be a plus.

Big Bore Throttle Bodies and MAFs
I recently tested the RC engineering big bore throttle body. This throttle body is 64mm vs the stock 60mm. The workmanship and attention to detail are superb. The throttle body casting is honed to tight tolerances so a good idle can be maintained and the throttle shaft is aerodynamically profiled with streamlined button head bolts that are staked, much like OEM. Although it felt like it was giving a lot more power in my SOTP evaluation, on the Dyno no power increase at all was registered just as I had previously predicted. My theory is that it improved throttle response so much that the engine seemed a lot more powerful. However, I think this mod is worth while just because of the vast improvement in feel and response. Perhaps with more mods, the engine will need the additional flow and the TB will actually help.

I also tested using a big 80mm MAF from a late model Maxima using a custom programmed JWT ECU. My engine is getting close to the point where it can top out the stock ECU but not quite yet. Even through the Maxima unit is nearly 45mm larger than the tiny stock MAF, I did not gain any power except for about 2-3 below 4000 rpm! My theory on this is that the larger hole helped the CAI resonate better at lower rpm. I don't think bigger or bored out MAF's like Stillen sells are worth it unless you are turboed or your engines are modified to the point where they can pull more than 5.15 volts on the airflow meter. This is the point where the stock MAF is maxed out.

Spark plugs and Ignition systems
There is a lot of controversy on the list on what is the best, most appropriate sparkplug for our cars. My opinion is yet another one but at least it is backed by years of racing experience and recent dyno testing.

Heat Range of plugs
Sparkplugs come in many heat ranges. This is so the plug can be matched to the type of use an engine receives. For low speed, short hop driving, the plugs electrodes must stay hot enough to burn away and self-clean fouling carbon deposits. For this type of driving a hot plug is needed. For high speed racing at high rpm, the plug can become too hot and glow like a diesel glowplug causing pre-ignition and detonation. This can quickly destroy an engine. To prevent this a cold heat range plug is needed.

The length of the insulator of the center electrode determines a plugs heat range. You can tell a cold plug from a hot plug by looking at the center electrode’s insulator. If the porcelain insulator is short, it is a cold plug. If it is long and extends deeply into the steel shell of the plug, it is a hot plug. This is because a cold plugs short center electrode has a short path to conduct heat out of the electrode. A hotter plug has a longer path and dissipates heat more slowly.

Most listmembers seem like they are unaware of matching the spark plugs heat range to the type of driving that they do. I wince when I think that many are squeezing nos or pumping turbo boost with the stock hot plugs.

In my opinion the best spark plugs for the SR20DE and DET are the stock Genuine Nissan NGK platinum plugs. I like a decent platinum plug. Platinum is a noble metal with a high melting point. Being almost inert, it is highly corrosion resistant even at high temperatures. That is why a platinum plug lasts about 3 times longer than a conventional plug. When used in the plug's electrode it resists erosion much better than steel.

Stock Nissan plugs have platinum in both the center and ground electrode for really long life. Most aftermarket platinum plugs only use platinum in the center electrode. I prefer for most engines, even the stock ones, to run the PFR6B-11 spark plug. This is the middle heat range for the NGK plugs. SR20 powered cars come with PFR5B-11 plugs, which are one heat range warmer. Originally when the SR20 was first introduced, the cars came with PFR6B-11s but they were fouling out during port storage where the cars are continuously being started, moved a few feet, and shut off. The countermeasure to high warranty on low mile sparkplugs was the switch to the hot plug.

The PFR6B-11 works well on high compression, turbocharged or NOS powered cars. For running extreme boost (more than 18 psi), a big shot of nos (more than 100 hp) or really high compression (more than 11:1) the cold PFR7B-11 plug is necessary. This plug will be on the edge of fouling during regular day to day driving so it can be considered a race only plug.

The SR20 has a shallow included angle of the combustion chamber. This makes for a quick burning, detonation-resistant chamber. I have also found that shallow included angle chambers for the most part do not like extended tip plugs. When experimenting with extended tip plugs I have found that the engine loses about 3-4 hp across the board. Many aftermarket plugs are extended tip. The theory behind extended tip plugs is that the extended tip puts the electrodes in a more turbulent section of the combustion chamber, thus helping them stay clean of fouling.

In the SR20 an extended tip plug puts the electrode too close to the piston dome screwing up flame propagation, thus losing power. This is important to consider if your are deviating from the Stock Nissan recommendation. Make sure that the tip of the plug that you are buying does not extend further than the stock plug’s tip. If you are running flat top or domed pistons, this is even more critical as the tip of the plug is even closer to the piston dome.

The SR20 has a powerful stock ignition that can fire through turbo boost and NOS. Gap the plugs at 0.045". If you experience misfire under squeeze or high boost (and the rest of the ignition system is in good condition, like the cap, rotor and wires) you can close the gap down to as small as 0.020" to prevent it. Go down in 0.005" increments until the misfire stops. Higher cylinder pressures cause by big NOS or high boost requires smaller gaps with the stock ignition. The smaller gap loses a little power but this trick can tide you over until you can get that snazzy turkey roaster ignition.

High Power Ignition
I haven’t run across a SE-R that has needed this yet but I suppose that over a 100 shot of nos or 18 psi of boost might need a high power ignition. Jacobs ignitions are crap. I would not bother with them. I prefer an MSD 6A or better unit. I have never needed an MSD on an SR20 yet but I have had very good luck with them on other cars including racecars. The Crane Hi 6 has gotten rave reviews also but they seem prone to burning out (two of my friends have been stranded because of a burnt out Hi-6). These ignitions are very powerful, capable of firing the spark plugs for over 30 degrees of crank rotation. Just the thing for high cylinder pressures.

I have a Nology coil booster on my SE-R. It seemed kind of hokey but I installed it. It has allowed my car to run smoothly even with the plug's electrodes completely burned off. When the coil booster was unplugged the car would barely run so I guess it works well. The Nology coil booster is the only easy way to hop up a 200SX’s ignition as the coil is an integral part of the distributor.

I believe I have found the limits of the stock SR20 ignition system. On Ryan's turbo car, when exceeding 10 psi of boost we developed a misfire which required that the plug gap be closed to 0.020". Even this was only good to 14 psi before misfire started again.
On my 11:1 compression NA motor misfire was happening until I closed the gap also.

So on really built cars I now recommend the MSD 6A or SCI ignition system. On 95 and later cars with an internal coil, MSD makes an external coil conversion kit for Hondas that also works on our cars. Just be sure to cut the primary conductor from the stock coil and fill the resulting hole in the distributor cap up with silicone or some of the extra power from your new coil will be wasted.

As a note, these ignition systems don't seem to work too well with Nology wires. I use either stock or NGK wires.
These high power ignitions will not give you much more power but they will eliminate frustrating misfire and help starting and low speed driveabilty.

Bosch Platinum
I hate these plugs. They have a weird center electrode that is flush with the insulating porcelain. What happens is that this electrode quickly erodes so it ends up being a depression in the porcelain, making the spark shoot out of a hole. Sparks like to propagate from sharp edges so I think they have a hard time getting out of this hole.

These plugs will absolutely not work for long in high compression, high rpm, boosted or NOS applications. The are marginal on a stock engine. In my experience they work OK for a few thousand miles then start to idle roughly and on modified engines misfire under load. It amazes me that an OEM level supplier like Bosch can make pieces of crap like these.

Some listmembers have recently dyno tested these plugs on stockish engines and have found them to be OK. This included some used plugs that were at least 20k miles old. My personal opinion is that these are pretty bad for most stock motors. The VG30 in my Pathfinder will barely run with these plugs. Kit Wetzler also experienced poor driveabilty in his NX2000 with these plugs.

[ Ed note: This is Mike's opinion of these plugs based on his personal experience. ]

Bosch Plus 4
Although I have not had any experience with them, Chris Pinthong and Dave Coleman have tested them and found them to work well. These plugs have an unusual design with 4 ground electrodes much like a rotary engine plug. Hopefully they are much better than the regular Bosch Platinum.

NGK V plugs
These work fine, just change them frequently. Be sure that the tip does not extend further than the stock plugs.Split Fire
I call these Miss Fires. They have an extended tip that the SR20 hates. The dual ground electrodes may have some merit by creating more sharp edges for spark propagation but this is moot when the extended tip causes hp loss.

Champion, AC and others
I don’t have any experience with these. Make sure the heat range and tip length is appropriate for our motors. I think that these brands have some premium labels that have unique electrode configurations to have more sharp edges for spark propagation. Some list members have had good luck with these.

The main thing to remember with SR20s is that the plug’s tip length must be close to the stock plugs or power loss will result and the heat range must be appropriate for the intended end use or engine-destroying detonation may occur.
Slika
B13 100NX GTi -> S13 200SX stage 2-> RS 182 CUP -> EJ92 slightly tuned -> RS 200 CUP -> CG9 -> P11 GT SR20VE N1

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Symon
univ.dipl.ing. Nissan
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Odgovor Napisal/-a Symon » 28 Jun 2007, 22:59

Še razlike med SR20 motorji. Konkretno SR20Di, SR20De in SR20DE

http://www.g20.net/forum/archive/index.php/t-36729.html
http://www.automotivehelper.com/topic2621.htm
http://www.g20.net/forum/archive/index.php/t-87.html

Zakaj sems e zdaj spomnil tole dati na forum? Ker bo Marlboro poskusil priklopiti eGT SR20DE P10 računalnik na svoj SR20De P10. Držimo pesti. Nekoč bova dala v njegov motor še redtop odmične in potem bomo videli koliko se poznajo razlike. Aja že sedaj ima izpušni kolektor od GTke. 8)
Slika
B13 100NX GTi -> S13 200SX stage 2-> RS 182 CUP -> EJ92 slightly tuned -> RS 200 CUP -> CG9 -> P11 GT SR20VE N1

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Symon
univ.dipl.ing. Nissan
Prispevkov: 4095
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Odgovor Napisal/-a Symon » 22 Dec 2007, 13:19

Guys,

Well, back in June (2006) I contacted JWT via email to basically get more valid information about the fwd roller variant of our motors; Well I ended up getting a phone call in return... and a great deal of information from that long conversations. Clark Steppler is a very knowledgable guy... and I commend him for sitting down and talking to me. Here is a passage that I wrote around 6 months ago in response... and its been sitting on my HD since then.

I have tried to get in contact with Clark for 5 months or so via email so that he can proofread it, so I can omit redundant information but I have not been able to do so. This could be due to the fact that they are a very busy company.

So in that respect, please take this as opinion & as simple instigation for good conversation... I had hoped to post this a long time ago but was reluctant to. I thought people would tear me apart since I don't have a ton of support. I'm not really afraid anymore and in that event I'll just remove it.

Please read the disclaimer and take it seriously, and please be respectful.

Ameen B. aka "Tokes"
The Differences in RR/Conventional SR20DE Cam Design + More info from JWT

Intro: Discrepancies and Controversies

Well, The main point of creating this passage is not to start arguments within the community. it was written to raise awareness in the differences of the roller engine and the conventional SR20 motor (highport/lowport spraybar). There is a lot of delusion around the forums when this subject was concerned. And frankly I got tired of it. Well most of you know that this sparked the beloved "JDM/USDM Roller Rocker SR20 Information Thread"

Check that thread here: http://sr20forum.com/showthread.php?t=147888

This all surfaced when I was asked a question "What would happen if a highport cam was installed in a RR motor?" From reading I assumed it wasn't possible. well, come to find out that the install unintentionally happened (not telling who) and there is a motor (could be more) that has supposedly been running for over a year like this. I was baffled. and I just don't like not understanding things. So I asked around, I read, I researched. and honestly I hit a wall. I thought I knew about the SR20. well frankly, and you can quote me here, "I don't know anything". I just read things and absorb passed knowledge before me.

Well, I asked around. and got together with James from the forum []98sr20de(t)[] and he helped me come up with a few unanswered questions. We decided to get some true camshaft/valvetrain information from some people that have had experience with the SR20DE from its introduction to its retirement. I emailed/called JWT's Support/Research & Development Team.

Here are the questions that were asked: http://sr20forum.com/showpost.php?p=155 ... tcount=110

The funny thing is, I went in with only a few questions about a roller rocker and came out with a lot of information that I thought some of you may like to read.

Disclaimer:
Please take the following information lightly and with open hearts and ears. The technical information that is displayed here was recorded from my recollection during a phone conversation with Mr. Clark Steppler (from JWT Support) and I. I take full responsibility for the information displayed here if it is incorrect. Anything I am unsure of has been shown in green text.

*** Feel free to comment, but if it sparks any sort of break in unification, disrespect toward anyone on the forum and/or JWT, or argument. it will be removed, plain and simple. If there is something you don't agree with here, please take the time to send me a PM and we can discuss it. ***



Conventional SR20 Information and Other things you MAY NOT KNOW!

Rocker Arms
First, to my understanding I always thought that the conventional rocker arms were made of stamped steel... I was told that this is NOT true. They are actually molded powdered metal.

The Conspiracy of the 94 Cam

Originally I had always thought that the only specific grinds for the stock FWD SR20's were.

Stock Spraybar Molded Rocker SR20DE Camshaft Information
Intake: Duration = 248* / Lift = 10.0mm (Highport)
Intake: Duration = 232* / Lift = 8.66mm (Lowport)
Exhaust: Duration = 240* / Lift = 9.2mm

Stock Non Spraybar Roller Rocker SR20DE Camshaft Information

Intake: Duration = 232* / Lift = 10mm
Exhaust: Duration = 240* / Lift = 9.2mm

Well, it appears that I forgot about a certain series in the mix. In the stock 94 Sentra lowport head, housed a 240* duration and 9.2mm lift intake cam... which is essentially a replica of the SR exhaust cam. This was the first and only year they used that cam profile in the Sentra SE-R... but the interesting thing is that they continued to build the Nissan Primera/Infiniti G20 in 95 and 96 with this special 94 intake cam as well. So, according to the cam change in the SR20 Motor (From 240* to 232* in the B14 SE-R), the rev limit went from 7.5 to 7k because of the intake cam, but in the 95/96 g20s the rev limit still remained at 7.5k...

In essence, the reason the rev limit was minimized is because the 232* duration cam doesn't function well at 7.5k. Most know when you switch the 91-93 highport cam in the lowport head there is a gain in power.. but your stability at 7.5k is now attainable as well. Also when you switch the 94 lowport SR20 intake cam, or 94-96 Primera/G20 lowport intake cam into your late lowport engine there will be a gain in power as well. and your 'stability' at 7.5k is then "regained". Even though this 'stability' is attainable, it does not mean it's advisable to rev that high... mainly because the SR20DE stock does not make its best power at this rpm. Remember, just because something is attainable doesn't mean it should be pushed to the limit. constant load at high rpm to redline isn't advisable all the time, unless you like engine wear. Additionally, no matter what camshaft is in your lowport SE-R, your rev limit will obviously be governed by the ECU that you are currently using.

Lowport or Highport Head. Which Flows Better (Stock)?

I never understood why this is such a huge issue around the forums. In all honestly, it doesn't really matter to me. but the internet is a huge ego measuring contest. so here goes. Everyone knows that the later lowport (95-99 SE-R at least in the US) was basically detuned from the demand of emission standards from my favorite agency in the world. As a direct result the cam changes (shown above) were implied. Even though the late lowport SR20 had a lower duration intake cam and a less aggressive lift the HP rating for the motor remained the same at the crank. 140hp from the factory. Now what does that mean? I'll tell you. It means in order to compensate for the less aggressive camshaft (to reduce emissions) something had to be done in order to match the HP ratings of the previous highport SR20 motor. Cue the enter for the Nissan Engineering Team.

The LOWPORT head flows better than the HIGHPORT head STOCK... out of the box... un-ported, untouched, tit for tat, STOCK. If it is modified (i.e. port work) the highport head has a higher potential of better flow. The reason is because there is a bump in roof of the port for the lash adjuster in the head of the lowport. The highport head has more potential for head flow because it necks down to go around the hydraulic lash adjuster... the area in the head on the short intake port is better.

Why are they "Detuning" our Cars? (Very Opinionated)
Well even in the late 90's emissions and other factors like fuel economy came into mind. In 2006 it is evident that the age of import scene lives, but there is something that is generally more important to this nation. Would you like to have a guess at what that is?

Well, the answer to the above question is FUEL ECONOMY aka good ol' mile per gallon. Think of this situation: if you are a car manufacturer and your only two options were deciding between designing an engine for power and performance, or designing it for fuel economy, which would you choose? Now take into account that the majority of people that represent the car buying force don't give a flying focus svt about air/fuel ratio, wideband, variable timing, whp, or anything else performance related. Car manufacturers provide for what the public wants, and the demand for a performance vehicle is below the demand for a fuel efficient econo-box at the moment. So what is Nissan (or any other car company/manufacturer) do in this case? You got it. they give in to the hype. It's either that or potentially lose revenue. Why else do you think that MPG rating is shown in every single car commercial you see anymore?

Well that is what I think. Now on to the Roller Rocker.

More Roller Rocker Differences from Conventional SR20DE (Stuff not in RR Info Thread):

The Head, Valve-Train, Spring Rates, and What's good about the RR SR20DE.
The Roller Rocker cylinder head is not different from the normal SR20... There are different code numbers but the head is essentially the same. The conventional head and roller head is essentially the same, aside from the fact that the Roller Rocker Motor has longer cam cap bolts...

The spring rates between the conventional SR20 and the Roller Rocker valve springs are different because of the difference in weight distribution and moment of inertia of the roller rocker arm. The pressure needed to compress the spring is very close.

The RR Motor has lighter pistons than the conventional SR20. Some versions used lightweight pistons because they have a smaller bore and 4CW crank. Keep in mind that the RR motor has been used in other countries before 2000 in Japan, UK, etc. (Almera, Primera, et cetera.)

As some of you know, the Roller Rocker motor and the SR20VE share the similar type Valve Cover. For this design the black oil separator (or sometimes referred to as the OEM "catch" can on the forums) was removed. A baffle was incorporated into the cover and the top was raised to compensate. A tube for Crankcase Ventilation was inserted at the lower right and the PCV Valve was moved from the left upper side to the upper right side of the valve cover. Through past experience in development the dumping of crankcase ventilation was determined to be better for turbo installation on the RR/VE valve cover... The RR cover has a better design hands down, and has more function.

The B15 & G20. Hmmm Compression Differences
Well in 2000 the Sentra was still selling in the US, but the B15 was Born, w/ a Roller Motor. In addition the G20 was still selling and housed a Roller Rocker motor as well. The b15 Roller Rocker Motor had a 2cc smaller combustion chamber, which is evident through its slightly higher compression than conventional (Discussed a bit in the RR Info Thread). The b15 uses the same type concave dishes on its pistons as previous rocker so nothing was roller specific. The g20 in 2000 variation has a 2cc smaller head, but has a bigger dish so that is why the compression is the same as the normal roller rocker.

For the Roller Rocker SR20DE, the camshaft profiles aren't all the same stock around the world. At this point the US has only had one set for intake and exhaust camshafts... but in Japan, Europe, etc, there are a few lists of durations/lifts. Some engines used different variants for valve springs as well... This explains why there are different rev specs for Roller Rocker motors overseas (i.e. 7.1k for some opposed to 6.8k or lower for USDM RR Motors.)

One interesting fact is that before the B15 ever sold in the US, JWT was already considering developing a cam using the roller rocker arms. This would have involved using the roller rocker arms and putting them in the conventional SR20... but the conversion would entail changing the valve train around. (changing valves, cams, springs, etc.) not promising. At this point in time I believe it was referred to as the "small base radius" cam.

Why are the Cams different in a Roller SR20. Why Can't I just throw Non Roller Cams in there?
You can throw a monkey in a gorilla suit in the Congo and he will live, but it doesn't mean he will function correctly. In other words, yes, now I understand that it has been done, a non roller camshaft has been installed in a roller rocker head. but it doesn't mean it is advisable. I have no clue what power it may or may not yield... but from a long discussion and a little thinking I know now that each cam (roller & non roller) has applications for each valve train's attributes. Let me explain what I found out from JWT:

The intake & exhaust valves are 3mm shorter in a roller rocker engine... then non roller SR20DE has a 40mm install height and different valve springs then roller. The RR has a 37mm install height. The center of bearings of the RR camshafts are all the same diameter as the conventional SR20, but lobes are very, very, very different. The rocker arms are different; the radius of contact is different, the distance from pivot point, the moment of inertia, the mass of the rocker, etc.

The initial point on which cam contacts the roller is different... by implementing a different cam into the wrong valve train one can incoherently advance or retard the cam motion... The phasing of it where it first touches the rocker arm is different. The Radius of curvature can make a great deal in the difference in contact stresses as well. It can produce a valve motion that it wasn't design for. In theory it can mess up harmonics of the valve train and at a certain rpm it may excite them...

The Roller Rocker arm has a different moment of inertia; the valve spring has to overcome the open and close motion of this arm at different RPM speeds... What controls this motion??? The valve spring controls this motion, and inherently controls stability of the valve train...

Obviously we know now that it is not impossible to run the non roller cam in a roller engine; I now know it has been done. The engine may run, but it may not run efficiently or the way it was designed (i.e. valve float).

When Designing the S3R (and other SR20 Camshafts & Valve Springs):

Brief General Knowledge on Camshaft Design
There is a lot of information that goes undermined when the research and development of a camshaft is discussed. A lot of the information that was discussed about design brought me back to my first years of engineering because we were talking about mass flow data, spring rate, inertia, kinematics, etc. Some of the stuff went over my head. and I was so intrigued and flattered during the conversation that some of the stuff I didn't write down because I was so into it. But in a nutshell I will just say that there are a lot of factors investigated, and there is a lot of math used. So I will keep it pretty general.

When designing camshafts for the SR20 the two first things to do are to attain a model head, and attain measurements to make a blueprint. This is a very difficult task as many things need to be taken into account. For example:

1) Cylinder Head - take cylinder head off and take measurements of it
2) Rocker Arm - out and take measurements to make a blueprint.
3) Where is the pivot ball at??
4) Spring Retainer Height??
5) Rocker Arm Height & Weight??
6) Etc.

The idea here is to make a model that is basically an exact replica of the motor that the camshaft(s) are being designed for. It is very important to create a precise model so that the flow data recorded will be similar and the cam will be functional. These representative models are built and tests (kinematics models) are run to acquire more information during the research and development stage. the more area under the lift curve

Different combinations of duration and lift are applied to the model. The tests data from the head/cylinder flow analysis is represented by graphs. This data is used to iterate and find power in one degree increments to find optimum performance for the applicable cam. The area under the lift curve generated is found using integration (remember calculus/physics/hydraulics much???). The more area under this curve the more flow/power. With the use of these models the optimum percent (%) increase of the number for mass flow data is recorded. This has to be very close to natural engine performance... so there is a lot of time and emphasis put in at this stage.

Specific Info for the S3R Camshaft

Well, if you didn't get the idea from the rest of this multiple prolonged paragraphs in this novel. the S3R and S3 cam grinds are different for a reason. the radius of curvature is different in each stock cam, which entails a whole different design for JWT. So vitally it's not just, and I quote, "cut and paste"... Because of difference in length of the valve heights, the orientation of the rocker arm, and the radius contact ratio of the stock roller rocker, the base circles of the stock cam lobes are a different diameter... For the S3R Roller Cams, the base radius on the cam lobe is smaller than on the S3... the lift is a little higher on the RR, but more duration had to be introduced. Again, the roller rocker arm is heavier, so its moment of inertia is different so therefore has to be modeled. The number of coils in the valve spring is different, as well as the spring coil diameter... although main pressure for each spring is similar, and the spring curves aren't that different, the spring rates are.

When designing the S3R, JWT originally came up short on flow so they increased the lift to get about the same performance of s3 cam on conventional engine. (just a bit lower).

Non Specific Information on the SR20 Valve Train (Engineering)!
Ideally, the higher the natural frequency of a valve spring, the more harmonics that can introduced. The more harmonics, the higher the engine speed, the more potential power. (I said ideally!!!)

In theory and you can push on the spring and it doesn't matter how much pressure is pushing back, the important thing is that valve spring has to be able to push the mass (in each case; the rocker arm) back to keep in contact with the cam lobe. If it doesn't then valve float can be introduced. Because the rocker arm is so heavy, to go higher rpm, a bigger spring must be introduced... There is a 50% weight difference for each rocker arm... so the moment of inertia is almost double.

When designing a spring, it is to my understanding that engineers may ask questions like.
1) How fast are we accelerating here?
2) Do we have enough spring force to control the mass?
3) Should I go to Wendy's??? I'm really hungry.
4) At what RPM will this spring hit resonance?

If you need a good definition of resonance, please take a look here, it mainly discusses sound waves, and wave amplitude, but the same information applies:
http://hyperphysics.phy-astr.gsu.edu/Hb ... reson.html

But, when an engine reaches a certain level of RPM, the valve spring can reach resonance where serious vibration takes place. At this point it can surge, spring can lose its function and wear, and damage can occur. So, in conclusion. Engineers design valve springs and the valve train together for a reason. further explaining the importance of matching camshafts to its applicable valve train.

Here is a quick link of some stuff about spring resonance: (It's a new subject to me; I don't know much)
http://64.233.167.104/search?q=cache:ed ... =clnk&cd=2


Future Applications from JWT?!?!?!
Well, in talking with from JWT I had the opportunity to hear a few prospective designs currently in the air. So lets get to the good stuff.

Will there be any more Roller Rocker cams in the Making?
There is a possibility to run a more aggressive cam and valve spring combination that the S3R for the roller rocker motor. So yes, the possibility is there, but it really depends on how good the market is for them. There needs to be a show in potential buyers. Simple economics. if there is no demand and supply is high, they will lose money. If you have serious interest I can tally this somewhere with full names and info and forward to JWT. The chances of finding enough serious people will be tough, but the possibility is there.

Special Roller Camshafts. with the Conventional SR20 Valves/Springs?
There is a possibility of doing a special camshaft profile where you can use the roller rocker arms and roller cams but with the conventional longer valve (40mm) and spring, but in this case there would be a need for a dual valve spring... This is if you SR20 people were interested, so it would depend on how many products they could sell to our community. The gains are having a very efficient valve train (less friction) and being able to utilize power by raising the potential rev limit.

I'm sure the development of this application will only further itself if there is a demand for it as well.

VVL Camshafts. Yes, VE Aftermarket Cams from JWT.
Some of you may already know this, and I may be relaying old information to you, but:

The VVL camshaft is currently in design at JWT. I was told that it will be coming within a few months... I don't know any numbers nor do I know any more information than that. I was just told that I could share it with you!


Reference Section:
Clark Stepplar - JWT Support, Research & Development

Thanks Again...
Ameen B
Here is a copy of some of the emails that were sent out for reference... They are pretty old though
Hello Clark,
I've taken the time to write about the stuff that we discussed about on the phone last week. This is the stuff below if you would like to proof read it. I tried to highlight the things that I was unsure about... it is quite extensive, but I wanted to send it to you first before I showed anyone as I don't want to reference you without your knowledge. If you would like anything taken out, or something doesn't sound right, please let me know. I took a lot from our conversation and I appreciate it very much.

Here it is...
-----Original Message-----
From: Clark S.
To: xxtokesxx
Sent: Tue, 27 Jun 2006 14:37:26 -0700
Subject: Re: contact list dist.:S3RvsS3
Ameen,

Is this your work number? What time zone are you in?

Clark

----- Original Message -----
From: xxtokesxx
To: Support1
Sent: Tuesday, June 27, 2006 1:24 PM
Subject: Re: contact list dist.:S3RvsS3

Yes my number is 513-xxx-xxxx

I usually work from 9-5 or 6:00pm but I'm pretty good about calling people back promptly.

Thanks for the fast return...

Ameen A. Bakare


-----Original Message-----
From: Clark S
To: xxtokesxx
Sent: Tue, 27 Jun 2006 09:21:43 -0700
Subject: Re: contact list dist.:S3RvsS3
Ameen,

I looked at your thread, seems like a lot of misinformation is going around. I'll try to answer your questions, but the phone would be better for me. Can you send your phone number?.... I will try to find time to call.

Thanks, Clark

----- Original Message -----
From: xxtokesxx
To: Multiple recipients of list contactlist
Sent: Sunday, June 25, 2006 7:10 PM
Subject: contact list dist.:

To JWT Research & Development, To Whom it may concern:

A team of friends from SR20forum.com and I had been doing some work on finding information on the Roller Rocker SR20DE Engine. The main cause was to raise awareness in the differences of the roller engine and the regular highport/lowport spraybar engines, and to clear the misconceptions being thrown around. We have most of the differences nailed aside from the true camshaft/valvetrain information. We had a few questions and we were wondering if the people at JWT could help (considering the experience, knowledge, and development your company has provided with this motor).

Here is the information that we have gathered.
http://www.sr20forum.com/showthread.php?t=147888

-------------------Here are our questions pertaining to the SR20-------------------

1) The main question that we were pondering was - What is the main difference between these stock camshaft profiles besides the duration and lift? Are their differences in the lobe base radius? This is what we know.

Stock Spraybar Stamped Rocker SR20DE Camshaft Information
Intake: Duration = 248* / Lift = 10.0mm (Highport)
Intake: Duration = 232* / Lift = 8.66mm (Lowport)
Exhaust: Duration = 240* / Lift = 9.2mm

Stock Non Spraybar Roller Rocker SR20DE Camshaft Information
Intake: Duration = 232* / Lift = 10mm
Exhaust: Duration = 240* / Lift = 9.2mm

2) We understand that the cams from a spraybar sr20 & a RR SR20 are from a different grind... We were told that this was because the valves for the RR engine were a little bit shorter that the spraybar engine. Do you know the length specs of the different valves?

3) There has been an occurence where a stock spraybar highport intake cam has been afitted into a roller rocker SR20. The car has been driving with no problems for over a year. The engine was pushed hard and driven everyday. Can you provide some feedback on this? Why did this work? Could this yield any damage?

4) Is there a difference in height of the stock stamped rocker arm and the stock roller rocker arm? If so, how does this effect cam design?

5) Was there a difference in the development for the S3 & S3R camshafts? In other words was their testing done on the cams individually, or was the S3R's design the same as the S3 with just the valve heights taken into account?

The following are the specs for the S3 & S3R series cams provided per your website...
Intake/Exhaust S3 cams = .442" lift, 260 degrees duration
Intake/Exhaust S3R cams = .450" lift, 262 degrees duration

This yields a 0.008" lift difference in lift & two degree duration...

6) Lastly we understand that the SR20 motor is no longer in production, but, is there going to be any more research and development for another roller rocker camshaft in the future?

Please let us know if we need to be more elaborate with these questions... Please let us know if you can be of assistance.

Thank you for your time and patience,

Ameen B. (SN: xxtokesxx at sr20forum.com)
James W. (SN: 98sr20de(t) at sr20forum.com)
Torej če strnemo. Lowport ima serijsko boljšo glavo kar je logično če vemo, da so odmične manj ostre, konjev je pa enako. Iz tega razloga se na lowport motorjih dobi ful konjev z highport odmičnimi.
Vir: http://www.clubprotege.com/forum/showthread.php?t=28568 (ja en Nissanovec na nekem Mazda forumu je to pisal :lol: )
http://www.clubprotege.com/forum/showthread.php?t=33964
Slika
B13 100NX GTi -> S13 200SX stage 2-> RS 182 CUP -> EJ92 slightly tuned -> RS 200 CUP -> CG9 -> P11 GT SR20VE N1

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