STI-RA: what's wrong OR how other rally cars have twice more power?

[ksalex]

I have stock 1995 STI Type-RA and always run it using pump gas (94) but
finally decided that I am ready to spent money and get more power.
So I spent thousands but did not get much.

Setup:
- stock 1995 STI Type-RA
- probably stock turbo BUT with 34mm restrictor
- new spark plugs, new coils (conversion from 2002+ WRX)
- wideband A/F sensor
- IAT sensor
- Vi-Pec ECU tuned by professional (I think)

Result
- 18 max boost (simply cannot get higher)
- 190lb torque and 170hp at wheels on 94 octane (10% ethanol)
- 200lb torque and 190hp at wheels on 105 octane (Shell, non-leaded, no ethanol)

Ok, I have less than stock HP because of restrictor but WHY I have stock torque while 18psi boost is much higher than stock ~14psi?

190lb at wheels that about 230lb at flywheel, so its just like stock (234lb).
Why?
And how other rally cars have 300lb and more?

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[ksalex]

BTW:
after Vi-Pec setup power delivered more smoother and I don't feel that much power increase after 4000rpm. May be I get more power on lower RPM, may be I just don't get anything extra?
Tuner did not check power before tuning

[bmxpunk]

You are working with a stock engine, and that along with a 34mm restrictor won't net you much.

Engines are systems and everything needs to be designed with that 34mm restrictor in mind. The restrictor really kills power after ~5000rpm so you can't rev more to make power, you must rely on making the engine breath more at lower rpm and create more pressure in the cylinders at those lower rpm. Raising the compression ratio to 9:1-10:1 will help, different cams/grind, larger turbo will help but you have to deal with a really leaky power curve or run aggressive anti-lag which brings about other problems like burning up turbos/exhaust manifolds/valves. Also having the heads and intake manifold ported for smoother airflow obviously won't be a bad thing.

Keep in mind the Subaru wrc cars ran really high compression,I have seen articles that reference 11:1+ and 3 bar of boost, along with that ( up to 2006 I believe) they also ran water injection to help cool the charge and combat detonation. Not to mention a very cool anti-lag setup (check out the "rocket" if you get a chance) on a decent sized turbo.

I am in your same boat, but I don't know yet what mine will lay down with the restrictor. I am hoping to find out mid September.

[Marnix]

Stock injectors? They may be maxing out.

[TommyAtomic]

Originally Posted by ksalex

I have stock 1995 STI Type-RA and always run it using pump gas (94) but
finally decided that I am ready to spent money and get more power.
So I spent thousands but did not get much.

Setup:
- stock 1995 STI Type-RA
- probably stock turbo BUT with 34mm restrictor
- new spark plugs, new coils (conversion from 2002+ WRX)
- wideband A/F sensor
- IAT sensor
- Vi-Pec ECU tuned by professional (I think)

Result
- 18 max boost (simply cannot get higher)
- 190lb torque and 170hp at wheels on 94 octane (10% ethanol)
- 200lb torque and 190hp at wheels on 105 octane (Shell, non-leaded, no ethanol)

Ok, I have less than stock HP because of restrictor but WHY I have stock torque while 18psi boost is much higher than stock ~14psi?

190lb at wheels that about 230lb at flywheel, so its just like stock (234lb).
Why?
And how other rally cars have 300lb and more?

I have highlighted your problems in red. This is rocket science but not the hard kind of rocket science. More power requires more fuel and more air in correct ratio. On the stock turbo with that restrictor it seems unlikely thats going to happen. Your thinking comparing rally cars and your sti-ra is flawed.

Rally cars are almost always extensively modified. The point of the restrictor is to limit the peak power output to level the competition between teams despite any other heavy modification that a rally car might have undergone including the turbo.

If you wanted to actually make power you needed more fuel/air and less restriction. I'm sure you know this already.

Replace the turbo with something lacking a restrictor. Get an up-pipe and highflowing exhaust. Get a low resistance induction setup(intake). Get larger injectors. Get the car retuned. This should all be common sense.

Is there a reason you havent done these things but have spent thousands of dollars? Were you planning on using the car in competition where the restrictor is required?

[ksalex]

Stock injectors? They may be maxing out.

Stock. But if this is injectors related problem, I would see high number on A/F gauge, right?
But I see 10 on full boost.

Engines are systems and everything needs to be designed with that 34mm restrictor in mind. The restrictor really kills power after ~5000rpm so you can't rev more to make power, you must rely on making the engine breath more at lower rpm and create more pressure in the cylinders at those lower rpm.

Yes, there is no power because of restrictor.
But if I have almost 30% more boost, I should have 10-20% more torque? While I have just stock torque...

Raising the compression ratio to 9:1-10:1 will help, different cams/grind, larger turbo will help but you have to deal with a really leaky power curve or run aggressive anti-lag which brings about other problems like burning up turbos/exhaust manifolds/valves. Also having the heads and intake manifold ported for smoother airflow obviously won't be a bad thing.

Sounds like a lot of money. Ah, then I better learn how to drive what I have ;-)

Keep in mind the Subaru wrc cars ran really high compression,I have seen articles that reference 11:1+ and 3 bar of boost, along with that ( up to 2006 I believe) they also ran water injection to help cool the charge and combat detonation. Not to mention a very cool anti-lag setup (check out the "rocket" if you get a chance) on a decent sized turbo

Well, WRC is absolutely different league and different money. But somehow a lot of cars around me use racing gas, so somehow they get advantage without investing 1,000,000.

[ksalex]

Replace the turbo with something lacking a restrictor. Get an up-pipe and highflowing exhaust. Get a low resistance induction setup(intake). Get larger injectors. Get the car retuned. This should all be common sense.

Well, I cannot remove restrictor - rally rules. And CARS thinking to decrease size of restrictor next year
Get larger injectors - I don't think this is the problem. I have A/F 10 at full boost.
Get the car retuned - I just did this, yesterday. That's where I spent money.

But still... I do not understand why 30% boost did not give me at least 10% more torque?
May be I calculate something wrong? E.g. 100lb at wheels means about 120-125 at flywheel?
I don't feel much more torque either but its more smooth...

Were you planning on using the car in competition where the restrictor is required?

It already in use
Rally

[TommyAtomic]

If you must have the restrictor, check the rules for your rally class. I would at least do an Up-pipe and TBE to reduce spool. Then retune. Have your tuner determine if your injectors are maxed and if-so go bigger.

As for the guys running racing gas. They are either running higher compression or are tuned with more timing advance. If the turbo restrictor is your only required restriction remove any other restrictions, do what you can to improve spool and retune.

[Paidfor]

Youre runnin 10.0 under full boost.......this is your problem. Lean it out to 11.5 at least......my car blows black fuel smoke when im at 10.0 under boost.

[AgentJ17]

Can you use no restrictor in open class or whatever they call it? Rob's 550 tune can use 18psi on the stock turbo. However, it involves a very neccessary upgrade to 04+ STi yellow top 520cc injectors. 18 psi is maxing out the stock MAF. So with a standalone system such as the ViPec you should be able to run on the internal MAP sensor only.

Let your turbo breathe man. Coated EL headers, coated up-pipe, free flowing TBE. Replace everything before the turbo inlet/restrictor with smooth flowing piping and a cold air box. I think JUN makes some cams for this motor (non-HLA) too, so you can have it cammed for more low down power. I think our heads already have a light PnP from the factory.

[ksalex]

I forgot to say, I have Turbo Back Exhaust (TBE?). But somehow my car is very-very quite. May be my catalytic converter is bad, makes too much resistance?

So, I need to change headers, up-pipe, etc?
If I won some money again, then I will spend...
Stock turbo is fine? I think my car suppose to have TD05-16g?

Can you use no restrictor in open class or whatever they call it

Open class must have restrictor. 34mm.
Production GT has 33mm restrictor.
May be Open class will have 33mm next year

Youre runnin 10.0 under full boost.......this is your problem. Lean it out to 11.5 at least......my car blows black fuel smoke when im at 10.0 under boost.

So tunning is not good?
Theoretically I can adjust maps by myself, Vi-Pec has free software. But I can make it worse, detonation, etc. While professionals charge a lot, not good idea to come to them too often.

[TommyAtomic]

Originally Posted by ksalex

I forgot to say, I have Turbo Back Exhaust (TBE?). But somehow my car is very-very quite. May be my catalytic converter is bad, makes too much resistance?

So you have a TBE. Does it have a cat. or a restrictive muffler. If its a big coffee can muffler does it have an insert or is it full of steel wool?

If its super quiet it is definitely a restriction. Fix it.

Originally Posted by ksalex

So, I need to change headers, up-pipe, etc?
If I won some money again, then I will spend...
Stock turbo is fine? I think my car suppose to have TD05-16g?

Start with an up-pipe. A non-catted up-pipe. Leave the stock exhaust manifold alone. With that turbo restrictor headers may be the wrong move. You could always pull off the stock exhaust manifold to have it ported and ceramic coated.

Originally Posted by ksalex

So tunning is not good?
Theoretically I can adjust maps by myself, Vi-Pec has free software. But I can make it worse, detonation, etc. While professionals charge a lot, not good idea to come to them too often.

Sure tuning is expensive and going back over and over is not cost effective. But you could have asked your tuners advice regarding power adders and removing flow restrictions before having it tuned. It would have been good to get multiple baselines by asking for before and after dyno runs with and without the turbo restrictor. Its the best way to know if your tuner was helping or hindering.

That restrictor is required so that everyones car runs like crap. You should not be surprised that it is successful. People have given you some good advice here except for the header. Without that restrictor a header would be a good idea though.

[ksalex]

Thanks for advices
Yeah, I should try to remove restrictor and/or muffler right on dyno.

So you have a TBE. Does it have a cat. or a restrictive muffler. If its a big coffee can muffler does it have an insert or is it full of steel wool?If its super quiet it is definitely a restriction. Fix it

It has cat, I think I cannot remove cat by rules.
have an insert or is it full of steel wool? I don't know. It looks like straight-flow muffler but where is the noise?

[TommyAtomic]

Originally Posted by ksalex

Thanks for advices
Yeah, I should try to remove restrictor and/or muffler right on dyno.

It has cat, I think I cannot remove cat by rules.
have an insert or is it full of steel wool? I don't know. It looks like straight-flow muffler but where is the noise?

You should double check that.

Pretty sure your STI-RA has at least 2 Cat's if not 3. One is in the factory up-pipe, at least one is in the exhaust. Rules regards cats are usually pretty simple - unless your class is 100% factory stock you generally must run a cat. But if you have 2 or 3 cats from the factory you can generally drop that down to 1 high flow aftermarket cat. This will get rid of alot of restriction and improve your turbo spool while keeping you within the rules.

[suberdave]

on a JDM WRX or STI you will not have a cat in your up pipe. it will only have one in the downpipe.

On my 96 JDM WRX EJ20G wiht ViPEC ECU i was putting down 293AWHP and 277AWTQ on just shy of 18 lbs boost and about 12:1 AFR.

I had stock TDO5h turbo, 780cc injectors, catless up and downpipe, 3" turbo back exhaust, one step colder NGK plugs, and FMIC.

The stock injectors were maxed out well before 18psi, they will need to be bigger.

this engine liked to run a little lean and lots of timing. but i have a knock light and never had any knock. when it was on the dyno, we kept making more power with a little leaner and more timing. (more than what some engines like anyhow)

here is my Dyno graph.


-=Suberdave=-

[ksalex]

The same boost but no cats and no restrictor and you have 50%(!) more torque!
What gas?

The stock injectors were maxed out well before 18psi

If injectors is too weak, it always affects A/F ratio?
If I have ratio 10 at full boost, my injectors are fine, right?

[ksalex]

Pretty sure your STI-RA has at least 2 Cat's if not 3

I am sure, my car does not have 3 cats. I think just 1.
And I checked rules, I cannot remove it (rules does not say anything about number - just "catalytic converter", so I need just 1)

[ksalex]

Your A/F stays near 12 almost regardless of RPM. Mine goes towards 10 when RPM raise.
Not very good tuning?

[suberdave]

as for fuel i am running the best pump gas i can get here witch is 92oct


what is happening is your ECU is loosing control of your injectors. yeah your AFR's are showing you have enough fuel. but i bet if you look at your duty cycle on your injectors i bet they are close to or over 100%.

at that point the ECU just tells them to stay open longer then they should and you just get as much fuel as they can flow in that amount of time.

when you have larger injectors you can control them by getting your duty cycle down under 80%... get some larger injectors, and tune it on a dyno with AFR logging.

-=Suberdave=-
www.suberdave.com

[blessthekellen]

Just do Rob's 550 tune and get your 300AWHP and be happy.
Yeesh, even the 440 tune hits around 240AWHP.

[Marnix]

Injectory DC can't go over 100%...

Tuning/mapping is expert/professional work and therefore expensive. However, engine failure and missed event(s) due to DIY tuning is more expensive and frustrating...

One more note, making boost is not equal to making power!

[ksalex]

Tuning/mapping is expert/professional work and therefore expensive. However, engine failure and missed event(s) due to DIY tuning is more expensive and frustrating...

Agree. But I spent over $5000 and I am not even sure I got anything at all
They did not check parameters of my car before tuning
I could buy JDM WRX for these money and have nice recce car.

[suberdave]

Originally Posted by Marnix

Injectory DC can't go over 100%...

I realize that you cant really run an injector over 100%. you cant have it open more than all the time...

However in the ECU it will read over 100%. (with stock injectors i seen mine as high as 115%) I don't know why. but it will allow it.
It is at this point you have no control over how much fuel goes into the cylinder. and it will most likely go super rich. and with that engine to rich will loose power.

-=Suberdave=-

[AgentJ17]

Thanks for clearing up the number of cats issues, Dave.

I said EL headers because I thought they improved spool and overall improved midrange power.

If your pushing 18psi and not running very lean on stock injectors, something is wrong.

Do you have the stock downpipe? If so you do not have a true a/m TBE.

[ksalex]

Do you have the stock downpipe? If so you do not have a true a/m TBE.

I am not sure if its stock, it has big/wide cat.
May be my injectors are not stock? But who would put better injectors and keep stock ECU?