RB20 Mods

[WDRacing]

I see alot of threads on swaps, but very few on modifications once the engine is installed. The RB20 and 25 are great platforms to start with. I'm a 20 guy myself, since thats what came with my Skyline GTS-t. But most of the mods should work both ways since the engines are very similar.

The first thing I did was to get rid of the stock exhaust, from the downpipe back. The turbine needs room to breath. But Most of you will already have that done with the swap.

The next thing I invested on was a boost controller. I never even bothered to install a boost gauge yet. Thats a bad idea. I was boostin 1.5 bar on a stock RB20DET. I couldn't figure out why I was going through a set of spark plugs every 2 weeks. I installed a boost gauge and realized I was about to grenade my engine. I think the Japanese high octane gas saved me.

So I was running 8 psi on low boost and 14 on high boost. It was ok for awhile, but I was getting beatin on a regular basis by people with more boost and more mods.

So I opted to go for broke...literally. The wife still hasn't let me live this down. I bought a HKS Exhaust Mani and External Wastegate. Along with a Garrett TO4E P-trim with a 96 AR. Which I didn't know at the time was a tad to big for a 2.0. None the less I bought the kit.

While I was changing the turbo I figured I might as well do some porting of my head, The stock head leaves alot to be desired. The cast impurfections seriously constrict intake/exhaust flow. Once I cleaned those up, I installed a set of cams from a RB20DE which have 8 degree's more duration then the turbo cams, while maintaining the same lift.

I also aquired a GTR FMIC and piping, which I completely covered in thermo tech exhaust wrap. I recommend using this on everything. It seriously reduces under hood temps which improve hp and torque on all motors, forced induction or not.

With the TO4 kit installed running at 12 psi was thrilling. The lag was awful, but it sure pulled hard once boost came on. So again I decided I needed more power. I replced the stocK headgasket with a HKS 2mm.

I also added the SMC Alcohol Injection Kit along with an MSD Knock Sensor.

With everything hooked up and running 100 octane gas, I was able to boost 25 psi with no knock indicated. The most I ever ran was 28. But that was under perfect circumstances.

Once I had the alcohol dialed in, I was seriously racing. I was happy for quite awhile...

WD

[dan240]

holy crap! boostin 25 without engine management? that's insane numbers! it seems like you've done a lot of work to your car thus far. Anyway, i've always been with the assumption that the stock RB heads flow quite freely? Another thing, wouldn't the 2mm headgasket decrease your already low'ish 8.5:1 cr? I'm an Rb25det guy, so i'm wondering if it holds true that the N/A counterparts to the RB/CA series motors have 8 degrees more duration???

Anyway, your setup sounds damn nice! keep it up man! =)

[apex_7]

That's an awesome setup! Thank you for posting your mods. I was wondering as to what my options are after I recieve my RB20 (hopefully next week). Have you ran it in the 400? I want to get a larger turbo, but I don't want to spend that much on it because I'm still in school. Any suggestions?:help

[Projekt]

<- thinks you're retarded for putting a 2mm head gasket on, but the 1.6s everyone else use aren't much better...

[dohctor_yaj]

wassup my rb20 brothas...

hey apex_7, i'm planning on gettin the T3/T04E with the .63 t/h and .50 c/h Garrett Turbo...should be about $600...I'm gonna do internal wastegate with the stock exhaust manifold...dont got cash for a nice manifold with external as i'm in school too...

no one has ever answered my question about what is the max boost you can dial on a internal wastegate though yet...:help

so for what i got at home for my rb20det:

walbro 2553 core radiator5" autometer carbon fib tach2" autometer carbon fib air/fuel guage2" autometer carbon fib boost guageHKS super sound BOVFat custom intercoolerACT Clutch for 95+ Maxima Modified Street Set

Still gotta get:HKS EVC III<-- please tell me if the Profec B is way better then this?Apexi SAFC IIIHKS turbo timerThermos FansT3/T04E with .63 t/h and .50 c/h550 RC injectors <-- I'm pretty sure they drop in...RIGHT?

Anything else missing for a 400whp recipe?How much will the RB20 MAF handle?What kinda ignition system should i get?

Date of swap: As soon as school ends --> Latter part of May

[WDRacing]

<- thinks you're retarded for putting a 2mm head gasket on, but the 1.6s everyone else use aren't much better...

Well, the huge turbo didn't help my low end and the car was built for drag only. So I wasn't worried about the loss of "Q" in the lower rpm bands.

COMPRESSION RATIO - Lowering the compression ratio allows the engine to run more boost with the same octane. For example, 8.0:1 vs 9.5:1 can tolerate another 3 psi. 3 psi gives 38HP. The 1.5 lower CR loses 3% (2% per point) or around 9HP in a 300HP engine. That nets 29HP (38-9=29).

Who's retarded???

WD

[dan240]

WD: i'm not calling you retarded at all.

but here's one discrepancy i've encountered.The hondas over here in north america (Inline Pro in Virginia) are running thick headgaskets around 2mm as well, and they've been proven to resist detonation very well. Yes, we're talking about 400-500 hp DAILY DRIVEN cars (proven and verified 3 years+). What i'm gettin to is........ that with adequate fuel delivery, and a strong enough HG, hondas have been capable of running insanely high hp daily driven vehicles.

I dont know if what i'm saying is making sense. but something that i've noticed about their cars is that they run THICK headgaskets and high compression comp. ratio pistons (perhaps to negate the lowered compression of the thick HG?)

WD, another thing i've noticed is that boost is variable, whereas compression is static. Why is it good to give up power when you have to compensate the power loss through boosting higher?

I guess in reality i'm saying that with good tuning, enough fuel, and a strong HG, High compression and boost > Low compression boost.

In addition, this makes for a quicker spooling and more responsive motor. As we all know, high CR = quicker spooling, and off boost, it makes for a more drivable vehicle

Dont get me wrong, but if hondas with their inferior motors can withstand this, why cant our nissans accomplish the same feat?

i'm thinkin about a 2mm HG + 9.5 CR pistons, a ****load of tuning and perhaps a PowerFC for the RB25det.

Most nissan guys have gone through the route of low compression + high boost. In terms of drag racing, our nissans are behind the hondas by far. There's more 10 second hondas than there are 12 second nissans, this is NOT meant as a dig against nissans. I'm a diehard nissan fan, but when an FF car with an inferior powerplant can rip 10's with such frequency, maybe it's time we rip a page off of the honda guys?

BTW, honda's have been embracing light weight, and more importantly short ratio gearing.

Can somebody shed some light on this.Call me retarded, but how do you guys feel about this?

[ZERO]

The main reason that you probably see more Hondas in the 10s than nissans is because there are more hooked up hondas out there than nissans.

As for inferior engines. That is not true. They are great engines, but their engine are designed with other plans in mind. You can't compare and engine that was designed to be N/A with one that was designed to be Turbocharged. They are two different classes. Even if you turbo the N/A engine, it was still designed to be an N/A. Obviously if you can tune it right it will be good, maybe even better. Ihave seen dyno graphs of an H23 DOHC NON-VTEC Prelude that put down 900+hp to the wheels. But as I said they are not designed specificaly for that and obviously you cant have that car as a daily driver because of reliability issues. However you could get an RB engine and pump out close to that hp and it will be more reliable at that setting than the honda.

Don't diss them because they are different. It's just like racism.

[Vrtgrumpy]

DAM WDRacing, Sounds like a good setup. Let me know how it runs.... Also, I want to know how the SMC Alcohol Injection Kit works out. I was thinking of running that setup too in my car. I am changing Turbos next week and I want to protect the motor from Detonation......

Also, Off topic, where are you at in Japan? I am frfrom Okinawa but finished Highschool at Camp Zama but lived in NAF Atsugi.

Grumpy

[dan240]

Zero: I was tryin to stir the pots of the guys here, therefore i used the term "inferior".

There are more hooked up hondas than there are nissans, but i said that there's more 10 second hondas than we've got 12 second nissans (in north america of course).

As you see i use to be an avid honda fanatic, so please dont take my words with offense. I noted that both Nissan and Hondas have different merits which make them both excellent motors.

What i'm inferring is that our blocks were built with turbocharging in mind, yet the n/a built hondas are puting better numbers down than we are. And as for the torque argument, they've got less torque than we do (Gearing). irregardless of this, they manage to run better times with equivalent hp, they also have the handicap of running an FF format.

That leads to my next question/comment. I don't think that they're in two different classes. If the guys at inlinepro in virginia can replicate #'s around 400-500 hp on a daily driven car for over 3 years, it proves that hondas are capable of retaining reliability even with forced induction. Whatever the case is, the B series and the SR/CA/RB have more similiarities than we'd (nissan enthusiasts) like to believe. Their internals are good up to about 400 hp (reliably) obviously with tuning and adequate fuel. *Note the emphasis i placed on tuning*

I hope that i'm not overtly being confrontational because i HATE to get into arguments online. I'm here to learn and ask questions and present some of my findings.

As for the rest of my previous post, what do you think about the compression/boost theory? I guess i should have been more specific with my HP numbers, but i'm lookin at around 500 horsepower.

Cheers,Carson

[WDRacing]

DAM WDRacing, Sounds like a good setup. Let me know how it runs.... Also, I want to know how the SMC Alcohol Injection Kit works out. I was thinking of running that setup too in my car. I am changing Turbos next week and I want to protect the motor from Detonation......

Also, Off topic, where are you at in Japan? I am frfrom Okinawa but finished Highschool at Camp Zama but lived in NAF Atsugi.

Grumpy

I'm at Kadena, she went well bro. I highly recommend the SMC kit. Easy to tune....you can easily add 8psi...

WD

[Projekt]

Well, the huge turbo didn't help my low end and the car was built for drag only. So I wasn't worried about the loss of "Q" in the lower rpm bands.

COMPRESSION RATIO - Lowering the compression ratio allows the engine to run more boost with the same octane. For example, 8.0:1 vs 9.5:1 can tolerate another 3 psi. 3 psi gives 38HP. The 1.5 lower CR loses 3% (2% per point) or around 9HP in a 300HP engine. That nets 29HP (38-9=29).

Who's retarded???

WD

your numbers are pretty arbitrary. your 2% per point of C/R is very off. i can tell you from personal experience that with my old MX-6 turbo i had a 7.8 with an upgraded I/C, turbo, piping, etc. i raced an mx6 with the stock turbo but non turbo, 8.6 pistons, and we were neck and neck.

isn't the rb20 8.5CR to begin with? lower CR to increase boost gives you more torque at the expense of power.

[Projekt]

and fwiw i don't think stock honda internals are good for 400hp. not all of them anyway, maybe the crank. and also, i dislike VTEC heads cause they're so damn complicated and wasteful [/rant]

[WDRacing]

your numbers are pretty arbitrary. your 2% per point of C/R is very off. i can tell you from personal experience that with my old MX-6 turbo i had a 7.8 with an upgraded I/C, turbo, piping, etc. i raced an mx6 with the stock turbo but non turbo, 8.6 pistons, and we were neck and neck.

isn't the rb20 8.5CR to begin with? lower CR to increase boost gives you more torque at the expense of power.

Dude, you'd have to have both engines on a dyno to compare them. Racing 2 different cars with 2 different drivers isn't going to prove anything. I got those figures from Kenne Bell. So I'm pretty sure they're close. Now they're going to very between engines. But I was just explaining my thought process. How many RB20DET's do you know of that have run 28 psi with stock internals?

As far as Q vs HP, I'll take Q everytime.

WD

[ZERO]

dan240:

Sorry dude, I thought you were being serious.I am presently owner of a Honda (91 Accord Wagon, which I am selling to get a 240) so I have been into honas longer than I have been into Nissans. I respect both of them equaly.

If you are interested in seeing power numbers that turbocharged Hondas put down check this page out: http://www.jgenginedynamics.com/dynotests7 you might find some of those quite impressive.

As for the theory of Boost vs CR. we all know that lower compression allows for more boost safely. The key word here is "safely". If you want to reduce your CR to 8:1 its your call. Personally 8.5:1 I think is pretty good for turbos. I would rather wait and get forged internals. That should be able to get you in the 500hp range safer than with a head gasket.

[Projekt]

Dude, you'd have to have both engines on a dyno to compare them. Racing 2 different cars with 2 different drivers isn't going to prove anything. I got those figures from Kenne Bell. So I'm pretty sure they're close. Now they're going to very between engines. But I was just explaining my thought process. How many RB20DET's do you know of that have run 28 psi with stock internals?

As far as Q vs HP, I'll take Q everytime.

WD

well if you lowered your CR by 1.5 then you're at 7.0 correct? you should be able to run 35psi on that i'd say. lowering the CR is a good idea if you have piss water for gasoline. remember torque breaks things, power doesn't.

[WDRacing]

Well, i'm not cetain how much a 2mm HG lowered my CR. I was figuring a whole point. Which would have made it 7.5. I also ran 104 octane gas on a daily basis. My fuel system was stock except for a RRFPR and BBK Pump. I used the Alky Injection as a fuel source since my injectors were obviously at max duty cycle as well as my MAF being at max noise.

I never drop the clutch when I launch, I also run heavy weight transmission and rear diff fluid. So that helps alot with the abuse.

WD

[Projekt]

7.5 is so low compression. i wouldn't be able to take it. i've had two 7.8s and they were dogs off boost....

[dan240]

guys, i'm not trying to be bothersome here, but what do you think of the setup i'm planning of running? it was posted earlier in this thread. Im asking because you guys have way more knowledge than i do, so tell me what you guys think and if it's plausible.

thanks guys!

[Projekt]

i'm not sure why you want 9.5 pistons if you're going to put a huge head gasket on it. that's counteractive. like putting 4 fuel pumps with 6 230cc injectors. if you want to make 400hp or whatever it is you're looking for get a turbo upgrade and an power FC, i'm sure that's all you need. (yes i'm including fuel/intake/exhaust/IC)

[dan240]

i'm not sure why you want 9.5 pistons if you're going to put a huge head gasket on it. that's counteractive. like putting 4 fuel pumps with 6 230cc injectors. if you want to make 400hp or whatever it is you're looking for get a turbo upgrade and an power FC, i'm sure that's all you need. (yes i'm including fuel/intake/exhaust/IC)

im wanting the 9.5 pistons and a thick head gasket just so i can have the added protection of not blowing up my headgasket, yet retaining a relatively high degree of compression. If i build up my bottom end, i'm gonna be running strong internals, so why not take advantage of that? The prospect of running low compression off boost scares me! driving in the city with a relatively high compression block off boost would be pretty nice, in addition to being able to spool the turbo quicker. Boost is variable, whereas compression is static. I'd rather have that power for city driving without having to wind up my motor to make power.

So in essence, running a thick head gasket decreases my CR, but it is also more resistent to detonation. This then would allow me to run a higher CR piston without the fear of grenading my internals. If i had a thin head HG, the CR would be increased, yet it wouldn't provide the protection that a 2.0mm HG would.

Cheers,Carson

[Projekt]

you do know that the thick head gasket reduces the compression right? so running a 2mm HG with the 9.5 CR pistons will make your compression lower than stock for no real reason...

i hope you don't think a thick head gasket gives you any form of protection over a normal sized one.

[dan240]

Projekt: if you'd read my prior post, you'd have seen that i clearly stated that a thick HG would decrease my CR.

Like i've stated in an earlier post, the Honda guys from the inline pro crew utilize a thick headgasket, copious amounts of tuning and they've been running mostly stock internals at 400 whp on a daily driven vehicle. Most of the guys out in virginia running the inline pro HG build their engines up using high CR and moderate levels of boost. If i'm not mistaken they're running thick HG's and 10.x CR pistons, in essence they're running lower CR than the piston indicates due to the thick HG, but there's no way that a 2mm HG on 9.5 CR pistons would decrease my CR to below stock levels.

As for the headgasket providing more protection from detonation, are you stating that a stock HG would be adequate would be adequate for high CR + boost? The thicker HG DOES provide more protection over the stock HG, otherwise the aforementioned honda B series engines would have grenaded a long time ago. In any case, i'm not trying to pick your bone, but just trying to necessitate a discussion on various setups for our cars. It's always good to have more opinions than not having opinions, in the end, we decide for ourselves what we choose. I'm just stating my case for High CR + Boost, and only that.

Proper fuel provisions + copious amounts of tuning + strong internals should allow for this.

Keep in mind, i'm only beginning to learn about this stuff, i'm not trying to force any of this stuff down any of your throats, I just think that it's best to keep an open mind on this stuff. I see night and all the other guys trying their best to help with informing nissan guys and i'm just trying to do my part in helping us succeed.

Respectfully yours,Carson

[WDRacing]

im wanting the 9.5 pistons and a thick head gasket just so i can have the added protection of not blowing up my headgasket, yet retaining a relatively high degree of compression. If i build up my bottom end, i'm gonna be running strong internals, so why not take advantage of that? The prospect of running low compression off boost scares me! driving in the city with a relatively high compression block off boost would be pretty nice, in addition to being able to spool the turbo quicker. Boost is variable, whereas compression is static. I'd rather have that power for city driving without having to wind up my motor to make power.

So in essence, running a thick head gasket decreases my CR, but it is also more resistent to detonation. This then would allow me to run a higher CR piston without the fear of grenading my internals. If i had a thin head HG, the CR would be increased, yet it wouldn't provide the protection that a 2.0mm HG would.

Dude....You aren't making any sense. You want to run 9.5 CR psitons cause low compression scares you. But you want to run a 2mm HG cause its detonation resistant. Dude...its safer cause it lowers your CR...thats it. What don't you understand??

If you want a daily driver that is forced induction then get a turbine with a small A/R side. So you come on boost at 2800 rpm.

I know of guys who run 20 psi all the time on a stock HG...but this is with an RB, not the KA.

I'm tired of hearing you say that Nissan is behind the times with Honda. Dude, i live in Japan. You know how many Honda's I see driving around smoking anyone.....none. The only real fast cars are Nissans, Mazda's and Toyota's in that order.

You need to read up on the affects of detonation and how to prevent them from happening. Then you'll be able to understand what it takes to build a forced induction motor.

Now please, no more Honda crap. If you want help you'll get it, just open urself up a little and listen.

WD

[WDRacing]

Another thing i forgot to mention, when you add a thicker headgasket to lower your CR, your screwing with the quench area of the combustion section. So its actually better to use low CR pistons then to use a HG.

WD

[dan240]

good stuff, thanks for the post! i'm willing to learn, and you helped me out there. I'm neither pro honda, nor am i pro nissan, but I was just observing what's been done here in north america. I mean no disrespect in all my posts in this thread whatsoever. And thanks on the tip about the detrimental effects of using a thicker HG. As i've stated i'm just learning, and I appreciate all the advice that you guys have given me. You guys probably think i'm a bonehead, but nobody starts off knowing everything.

WD, from what you've seen so far, what's the most effective street setup you've seen from an RB25det? I'm lookin for low end power and a crazy top end. Am i living a pipe dream or is this attainable?

Thanks,Carson

[WDRacing]

I'd go with a TO4 series turbine personally, but I can live with a little lag, You will probably be happier with a T3/T4 Hybrid. That way you come on boost alot quicker. As far as top end goes it really just matters how much boost you actually want to run.

WD

[Projekt]

thank you WD, ironic that we were arguing but now we're saying the same thing :0) it's funny how important quench area in a motor is. In hot rod mag a long time ago they had a CRX (sorry to bring up the honda, but this is to make a point) with 11.5:1 CR and 20psi on a JR supercharger. i emailed the guy and asked how he did it, all he said (being quite the **** i might add) was "Quench area." So i started reading up on it, and i discovered that the Mazda V6 (which is an extremely overbuilt motor) has an amazing quench area, so i wanna put one into an MR2 :0) That is also the reason i keep asking for pictures of the combustion chamber on the RB which no one seems to have.

[ItzGenX]

I would also like to add that a 2mm head gasket would obviously be resistant to detonation over a STOCK one, but have you ever thought about buying a metal headgasket with stock thickness? It would withstand the same that the thick head gasket could withstand while maintaining compression that you pay for and went through the trouble to put into the motor.

[Siddhartha]

right, and instead of blowing gasket, you put a hole in a piston...