BiG MiKE86

So I took my car back to the dyno yesterday after changing a few things that gave me problems last time - BOV, couplers, fans, boost cont., actuator, etc..

Heres the thing which baffled the fawk outta me and everyone there - I am running a GT2871r .64a/r with Tomei 256/256, 740cc, etc.. all the nessessary mods for 350ish rwhp

@ 10psi (ATP's "Special" Actuator) I made 296rwhp/256rwtq
@15psi I made 328rwhp/283rwtq - everything seemed spot on - for those 2 runs

So we Tried for 18-19psi - Car would completely fall flat on its face @ 6500rpm and 330rwhp as if it had some sort of rev limitter (PowerFC was set to 7400rpm) AFR's were perfect, timing was good, hp and tq curve looked great.. it Just Stopped @ 6500 rpm even holding the pedal down - it sounded like someone had turned on the dyno brake (if that makes any sense)

Under no Load or lower psi the car would rev out perfect in/out of gear

The PowerFC was reading the MAFS max voltage? @ 4400mv
The TPS graph showed it was reading fine
AFR's were perfect
Timing was dead on

WTF?

Sidenote: The shop owner said the turbo may be failing @ higher psi or Locking up (which should/would restrict air flow causing the symptoms) He mentioned that he'd seen this before - idk guys wtf?! help

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s15specR

Mines run to 25-26psi easily, if its falling dead on its face like you said it maybe something in the ecu, idk

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slider2828

He's bsing you.... What MAFS are you running? That is so weird.... on my N62 I run 18 PSI and I still don't max the MAFS out....

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smelly240

it isnt maxing out a z maf - thats for sure.

is there a "fuelcut" setting or a load limit on a powerFC?

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cotbu

The old 330hp lock out. Happened to me, but it was my cams they were stockers

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SoguRacing

bro, it's your cams. here's my dyno with boost control problems and step 1 hks 256/256 cams. you need more duration. mine at 10 psi with boost conrtoller problems as you can see.

otherwise same setup. i'm getting a retune with bigger cams and smaller injectors and now i have a boost controller installed for my next tune.

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BiG MiKE86

oh rly? ur car didnt completely die @ 6500rpm did it? im running Tomei 256 poncams in/ex
I couldnt tell ya - ill ask my tuner

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BiG MiKE86

Hey @ those rpms could you describe what happened? Because we kept it WOT and it didnt respond or do anything just fell off

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SoguRacing

honestly I wasn't in the car while it was being tuned. "steve" from "shadowerks" was. you'd have to pm him about that.

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cotbu

No, it didn't the run went to 7250rpm, and I don't even have a gt2871r... go figure! I was just trying to help you find a solution!

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smelly240

if shadows is doing your car - he would know -

i never used a PFC - and i know he's a haltech master (maybe pm brianw or shawn (RT)

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HREs on a S13 - check, 6262 - check, Girlfriend.... - nope

SilEightyKid

Would it be bad to use JWT S3 with JWT springs and retainers?

garagelu

Why would that be bad? Its good that you are using all high end, reputable components.

SilEightyKid

I don't know but would the stiffer springs affect the way the engine rev?

ni5mo240

Your power fc has a boost warning/limiter feature built in to it. When you try to dyno at 18-19 psi it cuts out, mine was doing the same thing until I turned the boost warn off

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codyace

I have no port and polish. I have nothing fancy on the cars.

Extrude Hone, External Gate, and Swain Coat are still LESS than getting a worthwhile tubular manifold. Even then, you can't be promised that it won't crack and won't make the same power.

I'm not sure what you read, but my car is full of real world parts, assembled by a real world guy. Trust me when I say, if I was building a race motor with this turbo, that it would make much more power and spin much higher...but alas, this is a street car.


I would be willing to say thta a 380 whp .64 car will be quicker than a 380 whp .86 car. That low end grunt and boost resopnse (you can't always look at a dyno chart, you need to look at power production over time). is what makes the car gravy. Peak numbers are for super street readers. Average TRQ are for fast car owners.

Seriously, hook at brother up I'm not scurrrred hehe. Although I may lose my fan club (oh sarcastic me) haha.

.64 2871r + 4.63 rear geras = smiles all the way to the bank.

Like, you couldn't rev above it? Or it's just not making power?

Check to see if you're blowing out spark? Gap them puppies down to .022

Not bad at all! S3's love stock springs, but love upgraded jwt springs as well (JWT no longer sells retainers, they use OEM ones)

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BiG MiKE86

I do not have the boost cont. for the power fc - im using a Greddy Profec-B Spec II so the Power FC Has no way to tell how much boost im puttin out

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BiG MiKE86

Didnt want to REV past 6500 - and it wasnt like bouncing off a rev limitter - it like hit a wall and died slowly even with the pedal to the floor

I will try gapping the plugs down some more this weekend thank you for the help

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SilEightyKid

Thanks for clearing that up. Btw cody, I see that you're running a Greddy elbow what's your input on that? Does it really help separate the gases and help spool? Do you think it would fit with the GT2871R GTS version since it has a S15 compressor housing.

slider2828

It does work because it is divided all the way down past the flange, so yes it does work. Yes it would fit because the turbine side is the same as all other T25s...

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S13 curtis

Jus wanted to know what you guys think i will be putting down on stock 8 psi
this is my set up:


SR20det Red top
GT2871r .64 3' inch inlet on stock boost
Greddy intake manifold
Megan exhaust manifold
Megan elbow
Stock Cams
370cc injectors
megan down pipe & test pipe
HKS HI power exhaust
Exedy stage 2
Stock 62 ECU
ARP Head Stids
Apex 1.1mm Metal Head Gasket
FMIC

codyace

Unsure, but i bet you max the injectors/maf

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slider2828

^^LOL that is so sad! Spend some money on other stuff instead of I have stuff... OMG... Lol.... I don't think you CAN run 8PSI on a GT2871R...

Sad....

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S13 curtis

i also have no a/c or ps i think it should be around 250whp give or take but i dono. im getting cams,740cc,and a Power FC.
well the car isnt running yet and i herd stock boost is 8 psi on the 2871r. I dont think the stock maf will be maxed. i have a N62 but its jus sitting in my garage until i get it tuned. I jus need to daily drive it for now, jus wondering though what it would make at what ever the stock boost is.

slider2828

Dude... OMFG.... Boost pressure does not mean that is how much air is running through your engine. GT2871R at 8PSI > T25 at 8PSI in airflow.... You will be running lean and asking to blow your motor... Or at least running close to Maximum flow for your injectors.... It is a risk for running that turbo with an untuned ecu as it may not be able to compensate for the increase in airflow into the motor....

Secondly you cannot run a N62 on a stock ecu without a piggy back or a standalone anyways....

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S13 curtis

no shit i knoe that. i was running 13 psi on the T25. no problems.,
and thats why my N62 is jus sitting, im waiting till i get enough money to buy the Power FC. Im not stupid. but im going to buy a wide band with my next check.

slider2828

Yah well at 13PSI did you measure what was your Injector Duty Cycle? Or didn't even bother at 13PSI on a T25?

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S13 curtis

I didn't bother, but i would guess it was kinda high. but i knoe im in need of 740cc. and the Power FC but money is pretty tight because i jus got this stuff. jus want the car driveable for now. I think it should be ok as long as i dont turn up the boost.

slider2828

At 13 to 14 psi you are running 95 - 100% of the injectors which is not safe at all. At 8psi it ain't going to be much better on that turbo... Trust me not safe to run it like that. I know money is tight, SO maybe you should just get a rom tune from JWT or enthalpy or something... A PFC is about 50 - 70% more because you will need to tune it and its like 100 an hour to tune on top of that....

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SilEightyKid

It looks like it would hit the stock wastegate diverter. Maybe you're referring to the GT2871R with the 3 inch inlet not the GTRS version.