SR20DET ready to go in???

[Tom Ngan]

Hey everyone,

All I have to say is WOW, this site has A LOT of information been fun sifting through everything, but now I feel the need to post up my plans hehehe.

I know this can be covered in a simple search, but I feel every person has different goals and needs, wants, financial abilities etc, so just wanted to hear some of your opinions. I bought my 2nd S13 coupe 2 months ago and the original owner had a SR20det that was from his wrecked hatchback ready to install into the coupe, plans didnt go through so he sold me the motor, the car and a whole wack of parts.

My GOAL is to have a completely reliable track car, run 13s 1/4 mile all day long without me taking massive downtime to repair stuff. Shooting for roughly 300rwhp or more. I currently have a brand new GT28R for the SR20, but I was thinking of upgrading to a GT2871R. Looking to run 12-14psi on the 28R and 10-12psi on the 2871R.


Currently the SR20 has:

94 SR20DET Blacktop

-75,000kms on it
-replaced turbo gaskets/hoses
-centerforce dual-friction clutch 1000kms
-modified aluminium radiator
-custom FMIC
-custom hotpipe/cold pipe
-new belts
-BOV
-Walbaro fuel pump
-Megasquirt custom Standalone system

I have already bought:

-Megan exhaust manifold
-Megan 3" downpipe
-Megan Racing pulleys
-Megan 3" Turboback exhaust
-Greddy Aluminum oil pan

I KNOW I need, but haven't bought yet:

-Nismo Motor/tranny mounts
-Nismo Thermostat

My BIGGEST concern would be the headgasket, SHOULD I replace it?
Should I get a Nismo FPR?
Should I upgrade my stock 370cc injectors?
Should I upgrade from GT28R to GT2871R?
Is there anything I'm missing?


I want to do as much as I can while the motor is out before I put it in, save me time/money later on. I'm not going to cheap out, but i'm not made of money either ;) , Also I have no immedient rush to get it going.

Let me know what you guys think, sorry for the long post! Its my first one :D


Heres a picture! I'm excited can't you tell???? :)

http://i59.photobucket.com/albums/g312/Boozor/picture001-6.jpg

[Matt Cramer]

I'd definitely replace the stock fuel injectors, probably with ones rated for 550 cc/min at least. Even if you bumped the fuel pressure up to 70 psi, you'll be asking a bit too much of the stock injectors to support 300 hp at the rear wheels.

I wouldn't bother with a new fuel pressure regulator, as long as your larger injectors still fit your fuel rail.

[DrIvEsldEwAyS]

if you plan on boosting it bigger in the future then while the motor is out it would be a good idea to replace the headgasket and may as well upgrade to ARP headstuds. and with the gt28r you will def. run 13's all day, i ran 13's with stock t25 boosting 13psi. goodluck

[Tom Ngan]

Would the notchtop 480cc injectors fit the redtops rail directly?
I only question the 370cc injectors because I heard a local shop here (PDM racing) has dyno'd over 320rwhp with stock 370cc injectors.


What sort of boost levels can a stock headgasket withstand comfortablely? And a upgraded headgasket? Thicker is better in terms of headgasket? I've seen 1.1-1.8mm headgaskets what is the difference? Apexi', HKS, Cosmetic????

Thanks guys for the replies!

[fliprayzin240sx]

I'd definitely replace the stock fuel injectors, probably with ones rated for 550 cc/min at least. Even if you bumped the fuel pressure up to 70 psi, you'll be asking a bit too much of the stock injectors to support 300 hp at the rear wheels.

I wouldn't bother with a new fuel pressure regulator, as long as your larger injectors still fit your fuel rail.

WTF? I wanna see anybody actually try to bump SR fuel pressure pass 55 psi on stock 370s and tell me what happens. Nubies dont need to start giving advice on shiet they dont know first hand.

Alot of the stuff your asking has been covered before, to give you an idea, everything on the car as far as turbo, headgasket, injectors, maf, all has a limiting factor of roughly 270~280hp. Anything more than that and your pushing the turbo pass its efficiency, 370s running static, stock maf fritzing. If you plan on upgrading turbo, you will need to change the maf, and injectors. Headgasket is the iffy part, itll depends on the condition of the engine but id change it since itll be alot easier to change it now than later when it does decide to give.

[Tom Ngan]

My setup doesn't include a maf? Apparently the standalone takes care of it.

So upgrading to 480cc S14 injectors and ARP studs will be sufficient?
What kind of headgasket though? And the difference between a thicker/thinner one?

Sorry I know its been covered, but I realize everyones different in terms of setup, would require more specific answers.

[DoriftoPnoy]

From what I remember, the "notchtop" SR20s came with 370cc injectors as well...

There was a thread on injectors and I forgot who said it but as a rule of thumb, 1 hp per 1cc. So supposedly 370cc can support 370hp. But I would take only 80% of that....

[garbury]

A thicker headgasket is going to lower your compression ratio slightly. This may also increase reliability due to a lesser chance of detonation. I would definately replace the headgasket while the motor is out. Its only like $225 w/studs and doing it now will save you many hours in the future.

If you only want 300 whp, the gt28r is going to be fine hitting 13s/12s, no point in spending more. The 2871r will put you well over 300whp and get you into 11s.

You need to make sure you know what you want because swapping setups will be costly because you will need bigger injectors (740s) for a 2871r.

[harlockssx]

I recommend going with a 1.2mm Tomei or Apexi Headgasket with ARP studs, if you want to get into it. Be sure to use copper spray to ensure a good seal. Forget about the smaller injectors & go with 740's so you wont ever need to upgrade again, unless you're shooting for over 450rwhp. They will be fine, even on a completely stock SR, provided you have decent tuning capability. Also, if you tear into the motor, toss some cams in, so you won't have to do that later as well...trust me, a LOT of us thought 300hp would be enough, only to be pulling all the parts we used to get there & go bigger. Brian Crower cams & valvetrain seem to be the better bang for the buck currently, although I personally prefer Tomei. DEFINATELY get the 2871...the GT28 is pretty weak, although the spool is great!

[Tom Ngan]

I guess 300-350rwhp is fine with stock internals?

Should I just get a 1.5mm or thicker headgasket, since it lowers compressions? What are the downfalls of a thicker headgasket?

How difficult is it to change the cams is there a proper procedure? I never really thought bout doing the cams...

[kensreliableb18b]

yes, u should go ahead and change out the headgasket before the motor is dropped in. whatever hg is fine: preferably apexi, pe, but greddy will also do (regardless of what other people say)

nismo fpr-yes, i would recommend a new fpr

you have your stand alone right? upgrade your injectors. i'd go with simple drop in ones; dont like the ones with collars and such

stick with gt28r for fast spool. but you're not going to achieve 300rwhp w/o upgraded cams. if you want to hit that goal i'd go with 264/264 setup, but i'd recommend a 256/256 setup from either tomei or hks, which would yield 280-almost300whp at about 1.2 bar boost. oh, and you running map or are you upgrading your maf? you'll need the z32 maf for the latter for your goal.

but all else aside, change your headgasket while your motor is out!!!

[ManoNegra]

- I'd go with 550cc injectors just be be on the safe side
- check/replace the water pump
- replace oil seals
- Apex metal headgasket and arp studs -- do it once, do it right
- new o2 sensor and plugs
- don't need a Nismo, oem thermostat is just fine

[Tom Ngan]

My standalone apparently neglects the use of a MAF, I asked this before, and the guy said that he didnt use a MAF when he had the SR running in his previous hatchback.... does this sound super weird???

What kind of oil seals are we talking about here?

Alrite cool, this is awesome, thanks alot guys for all this advice!

[fliprayzin240sx]

See thats the thing, if your running a mega squirt stand alone and you have no clue how to set it up, I suggest you find somebody who can first. Changing the parameters of the engine setup means, your gonna need a retune.

Personally, if i can do it all over again, this is exactly how i would do it to.

Power FC w/ D-jetro to eliminate the maf
740cc injectors
GT2871R (just figure out which trim you prefer .64 for faster spool up or .86 for a bit more top end)
Apexi 1.5mm HG
ARP head studs or for cheaper just brand new stock studs

With parts you have already and proper tuning...this should be more than enough to push you pass 300whp.

Bigger cams would be a niceaty, catch is you can only run 10.5 lift max before youll need to replace valve springs. Rocker Arm Stopper is a MUST

[Tom Ngan]

See thats the thing, if your running a mega squirt stand alone and you have no clue how to set it up, I suggest you find somebody who can first. Changing the parameters of the engine setup means, your gonna need a retune.

Personally, if i can do it all over again, this is exactly how i would do it to.

Power FC w/ D-jetro to eliminate the maf
740cc injectors
GT2871R (just figure out which trim you prefer .64 for faster spool up or .86 for a bit more top end)
Apexi 1.5mm HG
ARP head studs or for cheaper just brand new stock studs

With parts you have already and proper tuning...this should be more than enough to push you pass 300whp.

Bigger cams would be a niceaty, catch is you can only run 10.5 lift max before youll need to replace valve springs. Rocker Arm Stopper is a MUST

Ya I got in contact with the person who first designed the standalone for the car. He said he would be able to throw it on the dyno and tune it for me when the time comes.

Are 740cc injectors overkill? Wouldn't 480cc or 550cc injectors be just about right? I could always upgrade in a year or 2, and injectors are relatively easy to get at when the motor is in anyways.

The 0.64 trim would probably be good for the 71R, thats what I was planning to get instead of the GT28R if I was planning on upgrading... its going to my daily driver, so I still want it street friendly.

Maybe I should just hold off the cams, they seem like a nice addition, but right now I need to search up a bit more on cams before I think about using them. Like i'm not sure what 256, 264 means, or the lift, IN/EX, etc.

Thanks for the replies.

[fliprayzin240sx]

Trust me, 740cc on a GT2871R will not be overkill. I was running this setup minus the power fc. Like some people pointed out, 740cc will more than likely the last set of injectors youll need. Why do it twice over when you realize that you want more power later down the road? $500 on a set of injectors aint really cheap. The smallest injector id run would be 550s, but youll be pushing those injectors once you start cranking boost to upward of 20 psi on a GT2871R.

[Tom Ngan]

Awesome, just the kind of information I want to see.

ARP studs + 1.5mm HG + 20psi = no problem? (assuming GT2871R, I wouldn't bother with 20psi on a GT28R.)

I got a line on 800cc injectors i'll give my buddy a call then, might be worth it to upgrade.

[Tom Ngan]

Oh also,

in terms of a headgasket, what should the bore be? If I want to get a 1.5mm headgasket, what should the corresponding bore be to be more specific.

Also, how much will the compression lower with a 1.5mm headgasket?

Thanks so much.

[ManoNegra]

- imo larger injector than needed give you a buffer in case you decide to go for more power later on.
- no MAF I'm assuming means you're going MAP?
- what happened to 14psi? why 20 pounds all of a sudden. 14 is just about right for a daily imo.
- cams later on will mean another re-tune.
When is all this happening? Keep us posted.

[Tom Ngan]

I'm slowly amassing all the parts for the engine right now. I have no real deadline for it to be finished, but I'd like to have it in my car, tuned, ready for some track runs by summer time.

Currently I have a Accord as my daily driver and the insurance doesn't expire til April, so that'll be the deadline ;)

I'll probably do 14PSI on the 71R w/ ARP studs, 1.5mm HG with 600cc+ injectors.... If I feel the need to i'll get it tuned up to 18PSI or so and that'll be my dyno pull and my track days....

Keep you guys posted :)

[Matt Cramer]

WTF? I wanna see anybody actually try to bump SR fuel pressure pass 55 psi on stock 370s and tell me what happens. Nubies dont need to start giving advice on shiet they dont know first hand.

I was deliberately being absurd there to show how undersized the injectors are, not suggesting that was actually a good idea to run that sort of fuel pressure.

[fliprayzin240sx]

I'm slowly amassing all the parts for the engine right now. I have no real deadline for it to be finished, but I'd like to have it in my car, tuned, ready for some track runs by summer time.

Currently I have a Accord as my daily driver and the insurance doesn't expire til April, so that'll be the deadline ;)

I'll probably do 14PSI on the 71R w/ ARP studs, 1.5mm HG with 600cc+ injectors.... If I feel the need to i'll get it tuned up to 18PSI or so and that'll be my dyno pull and my track days....

Keep you guys posted :)

14 psi on the GT2871R .64 depending on what else you got to support it, should get you roughly 280 whp. For a reference, these turbos doesnt start to liven up till you go pass roughly 14 psi. The jump in hp from 14 to 18-20 psi is amazing....thats why to me, you must as well tune it for daily driving on street gas to as much as you can...20 psi or bust. You can always crank down the boost with a controller having too much power to you is an issue.