GT2871 USERS. SR motor

[Csomme]

You guys running a Power FC with a 2871r and the EBC, wheredo you keep your boost settings at? lol I mess around with mine constantly and just now got it where I like it.

[codyace]

Originally Posted by S13 curtis

stock is fine, thats what i ran and gave me no problems.

Again, running E85 certainly is a HUGE safety fuel compared to the rest of us shleps that rely on pump gas hehe.

[jspaeth]

Originally Posted by Csomme

You guys running a Power FC with a 2871r and the EBC, wheredo you keep your boost settings at? lol I mess around with mine constantly and just now got it where I like it.

I run an AVC-R along with a PFC....the AVC-R allows for much more flexibility in terms of seeing what you are controlling....i.e. solenoid duty vs. RPM....also has closed loop feedback as well.

[Csomme]

Originally Posted by jspaeth

I run an AVC-R along with a PFC....the AVC-R allows for much more flexibility in terms of seeing what you are controlling....i.e. solenoid duty vs. RPM....also has closed loop feedback as well.

really now? that's freaking awesome. Never thought of doing that.

[jspaeth]

Seriously? I thought it was well known that the AVC-R is far superior to the built in boost control in the PFC?

It's really simple. You literally just turn off the Boost control on the PFC, and run the AVC-R independently.

You end up having 2 separate pressure sensors....1 for the PFC D-Jetro, one for the AVC-R.

[D.Bo]

hey i got a question...i just picked a 2871r and the compressor side is a/r .50 and exhaust side is a/r .64....im not really lookin for big numbers but more response...should i just use the turbo as is now or upgrade the comrpessor housin to a a/r .60?

[jspaeth]

Originally Posted by D.Bo

hey i got a question...i just picked a 2871r and the compressor side is a/r .50 and exhaust side is a/r .64....im not really lookin for big numbers but more response...should i just use the turbo as is now or upgrade the comrpessor housin to a a/r .60?

Taken directly (errrrrr paraphrased) from Garrett's website:

"Compressor A/R - Compressor performance is comparatively insensitive to changes in A/R. Larger A/R housings are sometimes used to optimize performance of low boost applications, and smaller A/R are used for high boost applications. However, as this influence of A/R on compressor performance is minor, there are not A/R options available for compressor housings. "

TurboByGarrett.com - Turbo Tech102

[S13 curtis]

Originally Posted by D.Bo

hey i got a question...i just picked a 2871r and the compressor side is a/r .50 and exhaust side is a/r .64....im not really lookin for big numbers but more response...should i just use the turbo as is now or upgrade the comrpessor housin to a a/r .60?

pics please. pics say a million words. and i dont think the a/r 60 is an upgrade.

[HPballer76]

when all of you did your cams and valve springs and retainers did you replace the timing chain also? trying to decide if i need to replace mine when i do the cams.

sorry for all the questions just trying to make sure i do everything right.

[cotbu]

Originally Posted by D.Bo

hey i got a question...i just picked a 2871r and the compressor side is a/r .50 and exhaust side is a/r .64....im not really lookin for big numbers but more response...should i just use the turbo as is now or upgrade the comrpessor housin to a a/r .60?

Sounds like a gt3071 maybe?

[jspaeth]

Originally Posted by HPballer76

when all of you did your cams and valve springs and retainers did you replace the timing chain also? trying to decide if i need to replace mine when i do the cams.

sorry for all the questions just trying to make sure i do everything right.

It's good that you are trying to do things right. I did not replace mine, as this involves pulling the front cover in order to get to the crank sprocket, and was too much work for me haha.

Then again, I ended up with a mint SR20, which I paid a lot of money for, so I was fairly confident it hadn't been beaten on and had relatively low mileage.

It depends upon how many miles the motor has on it. Also, take a look at the chain itself and look fro cracks or nicks or bends or things like that.

Clearly, timing chains are way more beefy then belts, so we have that going for us.

[2fast4y0u]

its about time we have one thing going for us.
replacing the timing chain is fairly easy though. if i have my engine torn down for rebuilding, im replacing the timing chain...that simple

[jspaeth]

Absolutely, if you have it on a stand, I say do as much as you can possibly afford.

but with the motor in the car, it makes everything last thing that much more annoying.

[yabeet]

Older timing chains are still likely to stretch over time, the naked eye will not see this though.
On my S14 SR I want to keep vct and Im thinking of running 256/264 in/ex Greddy or HKS combo with a 2871 .64, leaving the rest of the motor stock [new pump, timing parts & rocker arm stoppers only]
Should running stock valvetrain be ok like the companies say it is?

[jspaeth]

Originally Posted by yabeet

Older timing chains are still likely to stretch over time, the naked eye will not see this though.
On my S14 SR I want to keep vct and Im thinking of running 256/264 in/ex Greddy or HKS combo with a 2871 .64, leaving the rest of the motor stock [new pump, timing parts & rocker arm stoppers only]
Should running stock valvetrain be ok like the companies say it is?

I could be wrong, but I am pretty sure that the biggest factor is the lift of the replacement cam.

What are the lift specs on the cams you are looking at?

[yabeet]

10.5mm so Im thinking it should be ok. Starting ar 11+mm is when they recommend upgrading the springs so they can compress more correctly without making contact with itself.

[jspaeth]

Originally Posted by yabeet

10.5mm so Im thinking it should be ok. Starting ar 11+mm is when they recommend upgrading the springs so they can compress more correctly without making contact with itself.

Yes I believe stock valvetrain is fine with 10.5 mm cams, however, you may not want to rev it higher than the OEM redline (I think it's 7400-7500).

Might want to wait to hear someone else's opinion. Actually, with higher lift cams than stock, but stock springs/retainers, you may actually want to rev LESS high....not 100 certain though.

[HPballer76]

Originally Posted by jspaeth

It's good that you are trying to do things right. I did not replace mine, as this involves pulling the front cover in order to get to the crank sprocket, and was too much work for me haha.

Then again, I ended up with a mint SR20, which I paid a lot of money for, so I was fairly confident it hadn't been beaten on and had relatively low mileage.

It depends upon how many miles the motor has on it. Also, take a look at the chain itself and look fro cracks or nicks or bends or things like that.

Clearly, timing chains are way more beefy then belts, so we have that going for us.

alright thank you. i guess i will just wait and see if i end up taking the motor all the way out or not. but i am fairly certain mine is in good shape since i have an s14 sr that was an auto when i got it and i have not had any problems with it.

[codyace]

Originally Posted by jspaeth

Absolutely, if you have it on a stand, I say do as much as you can possibly afford.

Solid advice for sure. I've never bothered with a new chain though...I mean if you're dealing with some abused car based upon other parts of the motor it may not be a bad issue, but it takes quite a bit to wear the chains out. That tensioner has a TON of 'slack' take up ability

Originally Posted by jspaeth

Yes I believe stock valvetrain is fine with 10.5 mm cams, however, you may not want to rev it higher than the OEM redline (I think it's 7400-7500).

Might want to wait to hear someone else's opinion. Actually, with higher lift cams than stock, but stock springs/retainers, you may actually want to rev LESS high....not 100 certain though.

There are many factors involving 'safe' limits of cams, not so much the hard numbers. Ramp rate, lobe design, etc etc all go into it. For example: With JWT cams (like the S3) it has a 0.442" lift (11.2ish mm)...and they are plenty safe on stock valvetrains to 7850 (where they set their limit at).

S4's have a 0.464" lift (11.7mm) and they too are safe to 7850 on stock stuff. Crazy huh?

But The C1 cams at .476" lift (12mm) require springs.

Just some food for though. The crappy thing about any cam in any motor is that is a HUGE discrepancy between measurements, lobe design, and general R and D. Sure a cam may make power, but being safe, and harmonically sound are very different. I mean, there is just TONS of engineering involved with cams it's rediculous.

[jspaeth]

Listen to Cody, he knows what he is saying....

But to answer is question, would you agree that if a reputable manufacturer (Greddy, HKS, Tomei, BC, etc.) say the cams are drop in and require no other head modifications, then it is safe to do so?

[codyace]

Originally Posted by jspaeth

Listen to Cody, he knows what he is saying....

But to answer is question, would you agree that if a reputable manufacturer (Greddy, HKS, Tomei, BC, etc.) say the cams are drop in and require no other head modifications, then it is safe to do so?

I wouldn't put BC in that group at all, considering they are a copy cat company

But yes, I would certainly trust a major manufacturing company in regard to their claims as of what is safe, and what isn't. They have their own RD involved. Will they spin higher? Maybe...but no reason to try and prove HKS or JWT or Greddy persay wrong, as they aren't going to care


However ensuring proper install is the main thing. Following FSM spec is KEY.

I will say this though, for as many 'options' as we may have, you guys should see some of the domestic stuff I've had to help with. You have LSA to consider, and new vs old lobe designs, vs manufacturers haha. It's certainly another art in itself.

[yabeet]

Originally Posted by codyace

Solid advice for sure. I've never bothered with a new chain though...I mean if you're dealing with some abused car based upon other parts of the motor it may not be a bad issue, but it takes quite a bit to wear the chains out. That tensioner has a TON of 'slack' take up ability



There are many factors involving 'safe' limits of cams, not so much the hard numbers. Ramp rate, lobe design, etc etc all go into it. For example: With JWT cams (like the S3) it has a 0.442" lift (11.2ish mm)...and they are plenty safe on stock valvetrains to 7850 (where they set their limit at).

S4's have a 0.464" lift (11.7mm) and they too are safe to 7850 on stock stuff. Crazy huh?

But The C1 cams at .476" lift (12mm) require springs.

Just some food for though. The crappy thing about any cam in any motor is that is a HUGE discrepancy between measurements, lobe design, and general R and D. Sure a cam may make power, but being safe, and harmonically sound are very different. I mean, there is just TONS of engineering involved with cams it's rediculous.

Cody, going with a stock S14 motor, 2871 .64, Greddy IM and Tomei manifold, what Jim Wolf cams would you recommend me while keeping stock valvetrain? I would prefer to keep vct, but am open to opinions, your input is smashing so far mate!

[codyace]

Originally Posted by yabeet

Cody, going with a stock S14 motor, 2871 .64, Greddy IM and Tomei manifold, what Jim Wolf cams would you recommend me while keeping stock valvetrain? I would prefer to keep vct, but am open to opinions, your input is smashing so far mate!

Any of the JWT cams are not going to be VTC compatable. However, that is something that would not be a 'make or break' point, as any decent cam you run is going to produce better power than any good cam that retains VTC.

I really prefer the S3 cams for these setups. My general 'rule' is that T2 flanged turbos work best with S3 cams, and T3 flanged turbos work best with S4's. S3's really promote better mid range, with S4's being on the high end of the RPM band. A selling point to me, is that JWT cams do not require any valvetrain upgrades...so you can keep stock springs/retainers...saving money in the end when comapred to a HKS 264 step II or a Tomei cam persay. This is not to say that the HKS or Tomei cams will not make power, as the ymake great cams...I just prefer JWT for the simple install, and lower end cost. (Plus you can find used JWT cams all over the sr20forum, and sr20-forum, FWD sites for great prices)

[yabeet]

So last question Cody, to rid of VCT, I will buy an S13 intake cam and sprocket and an exhaust cam that is the same from S13 thru S15 SR engines?
Thanks!

[codyace]

Originally Posted by yabeet

So last question Cody, to rid of VCT, I will buy an S13 intake cam and sprocket and an exhaust cam that is the same from S13 thru S15 SR engines?
Thanks!

Yup! Make sure you get S13 cams (well, B13/B14 are the same as well) and then to correctly remove VCT you should unplug it, as well as replace the the cam gear as well (intake cam gear only). Chain remains the same.

I may have a set of stock cam gears if you want them,but I'd like to look for sure. PM me if interested, they aren't doing me any good hehe.

[yabeet]

Thanks Cody, I will let you know if I need one, Im going to check with friends to double check if anyone has one kicking around, if not Ill send a PM your way. Thanks for all the excellent help

[miller1775]

took my s14 w/redtop to the dyno. stock motor with gt3071r and a safcII on 16lbs made 398 whp and 350tq on a dynojet.

now tore the motor down boring to 87mm with apexi head gasket with wisco 9:1 pistons, bc rods, all acl bearings, stage 3 bc cams, valve springs, and retainers, hks rocker armstoppers everything will be sealed up with arp studs all around and tuned on a AEM EMS tuned by Tampa Mike.
Should have it back together by may sometime wish me luck on the next dyno.

oh and the 30r rolls the hell out. v8's tend to have a problem with me haha.

[sidewaysil80]

i just read this entire thread in one sitting and i'm still stumped! i cant decide between the 28rs .86 and the 2871r .64. i had the gt2871r paired with undialed bc cams (this was b4 it was discovered they need adj. cam gears) and it was HORRIBLE laggy. to the point where i downgraded back to an s15 turbo lol. i'm piecing together my new motor build and cant decide which to run... i'm going with tomei cams this time for sure.
obviously the 28rs will spool 15-17psi quicker...but how much faster? and at what efficency? i've read that most of you guys are hitting full boost around 3800 but thats like 19+psi and for a setup that i'd like to keep no more then like 330whp...is the 2871r necessary? i guess i'm just traumatized from my last experience with it LOL

[jspaeth]

With stock intake manifold, you can slap on the 2871R with your toda cams and hit 17-18 psi by roughly 3500-3700 RPM.

Your tq will probably start dropping off pretty early though, around 6K bc of the stock intake mani.

But you should easily see your 330 whp goal with that turbo and those cams with everything else stock.

[djcobra]

If you want 320-330whp then go with the GT28RS .86 trim will be brilliant. I have the same turbo but in the smaller trim along with HKS Step 1 cams 256/264, 1.1mm Apexi' HG. Response is amazing, perfect for the street. Oh, i'm hitting almost 330whp at 15psi using 92 octane, end of the day its all about the tune! see my signature...

Steve.