STI turbos'

[IheartSTI]

I was wondering what turbo you guys would choose for the STI. I dont plan on upgrading for a while(if Necessary) but i wanted to get some good ideas. I want a turbo that can help get me to about 425whp-500whp, but i want a turbo that will spool quickly enough for some out of the corner power. Should i just keep my stock turbo?
You guys are probably are all at the charity run sorry i could not make it up there. thanks for everyones time and help

[Kevin M]

500 hp at the wheels is a whole hell of a lot of power. Making that much power means redoing basically every system in the car. Otherwise it's no different than making a WRX get to 600ish horsepower too. More importantly, the car wil become extremely one-dimensional. Well, two if you count dyno ownage. But forget about road racing or autocross with a turbo that big.


Edit: As this is my 555th post, I am no longer permitted to post further, so you'll have to get details from the rest.



555! w00t!

[ArthurS]

Originally Posted by BAN SUVS

Edit: As this is my 555th post, I am no longer permitted to post further, so you'll have to get details from the rest.



555! w00t!

Sweeeeeeet

[tysonK]

Yah are you sure you want 425 at the wheels eventually?

That is a ton, like Kevin said you have to consider the whole concept of the car with that rather than just a turbo.

[IheartSTI]

should i just keep stck turbo?

[Kevin M]

Originally Posted by scoobanader

should i just keep stck turbo?

Not necessarily. A VF22 is an excellent first step. Beyond that there is some debate. But, with the larger block, the VF22 on the STi will feel a whole lot like a VF30, or even something slightly smaller on a wRX- only much faster. I personally am planning a STi block/VF22 combo for my RS. Should be a great combination of drivability, low lag, and good power.

[qksubi]

What do need this much horse power for Drag, street autox wheel to wheel

[Dean]

I think Eric has a geat question... Why HP? What do you want to do with the car? If somebody starts woth HP, it usually means they want a drag car. If you want to turn, that is further down the list.

I would also guess that you can get a significantly more power out of the stock turbo by upgrading the exhaust, intake, and ECU before you run out of turbo.

[Kevin M]

Originally Posted by Dean

I would also guess that you can get a significantly more power out of the stock turbo by upgrading the exhaust, intake, and ECU before you run out of turbo.

Yeah there's another 50 whp in the stock turbo exhaust and ECU work. You know better than to suggest an intake though Dean.

[Dean]

OK, I had forgotten about STI boost creep, so the order should probably be Wastegate port, flash, exhaust, flash... Somewhere in there, replaceing the stock paper filter with a high flow, snorkle mod(Does the STI have a snorkle?), and/or intake wouldn't hurt. Despite what Kevin thinks, intake is not just a new peice of pipe and a cone filter. And exhaust can be as simple as gutting the down pipe all the way to full turbo back...

[Kevin M]

There are two kinds of intake mods- ones that disrupt the MAF signal, and ones that don't. One has the potential to cause premature engine failure, and the other doesn't do squat. So why get either one? I'm not personally sold on the whole different filter aspect. I personally don't see how it makes a big difference, especially on a forced induction car. And besides, filtering the intake air to keep dirt and grit out of your turbo is MUCH more important than 5 hp. The silencer mod is more for sound purposes than for power gains.

[IheartSTI]

Originally Posted by BAN SUVS

There are two kinds of intake mods- ones that disrupt the MAF signal, and ones that don't. One has the potential to cause premature engine failure, and the other doesn't do squat. So why get either one? I'm not personally sold on the whole different filter aspect. I personally don't see how it makes a big difference, especially on a forced induction car. And besides, filtering the intake air to keep dirt and grit out of your turbo is MUCH more important than 5 hp. The silencer mod is more for sound purposes than for power gains.

serious tuneres might take the chance with the dirt and grit to get that extra 5 hp. 5hp my not seem like much but every horsepower helps.

[Kevin M]

Originally Posted by scoobanader

serious tuneres might take the chance with the dirt and grit to get that extra 5 hp. 5hp my not seem like much but every horsepower helps.

I would disagree. If you can find me a shop that recommends intakes on a Subaru, and knows Subarus well, then I will show you a shop that is more interested in the margin they make from intakes than in making you faster.

click here for a good explanation of why intakes are unnecessary at best, harmful at worst.

[IheartSTI]

After reading that i further understand. thanks

[Dean]

Originally Posted by BAN SUVS

There are two kinds of intake mods- ones that disrupt the MAF signal, and ones that don't. One has the potential to cause premature engine failure, and the other doesn't do squat. So why get either one? I'm not personally sold on the whole different filter aspect. I personally don't see how it makes a big difference, especially on a forced induction car. And besides, filtering the intake air to keep dirt and grit out of your turbo is MUCH more important than 5 hp. The silencer mod is more for sound purposes than for power gains.

It's on I-Club, it must be true...

I'm not sure I'd use the word "squat". Physics is physics. The shorter, and less resistant the path; the colder and higher initial pressure the air charge; the better, period. I realize we are takling about small numbers, but everything helps, and some of these are fairly low to no cost mods.

The WRX, and STI have relatively poor engine bay venting, especialy at no to low speed. The the TMIC sitting almost right on top of the turbos doesn't help it any... Every little bit helps is all I'm trying to say.

[Kevin M]

More is indeed more power to be true. But this particular method, to me at least, isn't worth the cost in terms of hotter intake air, and more importantly the squirrely MAF readings caused by changing the intake tract. 5 "free" horsepower would be great- 5 hp that may very well have the effect of shortening your engine life? Not worth it to me.

That is a seperate matter entirely from discussing the merit and efficiency of the stock plastic intake parts. Fact is, they are borderline awful. But, the ECU is expecting the MAf reading to be true to the calibrations based on that suckiness. Plus, you can't change the efficiency all THAT much, especially on a turbocharged motor.

Also remember, the supposed power gains of changing an intake come from tweaking the MAF signal. This is something far better achieved by tweaking the other side of the fueling equation through ECU remapping.

As for the fact that I linked an i-club thread, I did so because I wrote most of the pertinent posts in it, and it saves me the trouble of repeating myself. My views are formed after absorbing quite a bit of first and secondhand knowledge from several sources, most prominently Shiv, Nate, and my own understanding of how electronic engine management works. It's been backed up by dynomometer testing. When I finish my swap, I plan to find a way to conduct yet another semi-scientific test of various intakes to see how much difference the theoretical efficiency difference makes, when taking proper tuning into account.

[IheartSTI]

If there is a lot of hot air in the engine bay shouldn't we do something about it? we can put a FMIC to get rid of heat soke, and we could also put a louvered hood in witch should reliese the engine bay heat very quickly(the faster speeds the better cooling). would the engine bay be cool enough to put an intake on it? there wills till be heat coming off the turbo but it might releise qucik enough not to effect the intake

[Dean]

I do believe a ECU tune was part of every step of my suggested order: "Wastegate port, flash, exhaust, flash... Somewhere in there, replaceing the stock paper filter with a high flow, snorkle mod(Does the STI have a snorkle?), and/or intake wouldn't hurt." Doing any intake changes in association with one of the other steps imediately prior to a flash, should not yield any "engine shortning" effects.

I also have an ongoing issue with the supposed danger of CAIs. In one breath people comment on how incrediably inteligent the Subaru ECU is, and then in the next claim it can't handle a MAF reading that is a little out of whack. What exactly is the tollerance for MAF sensor callibration, and what is the variation in stock intake tract flow? All of a sudden, the ECU is going to ignore EGT, knock, and O2 Sensors, and take the MAF as gospel? I just don't buy it.

I would bet the ECU actually continiously balances all of the sensor inputs into it's A/F calculations/settings, but I admit, I do knot know what it does. I have actually seen next to zero actual science behind the CAI discussion. Most is anecdotal at best, and often associated with people who have done a significant amount of other tuning, not just the CAI.

I am not saying CAIs are the greatest thing since sliced bread, only that an optimized intake tract can enhance the performance of just about any vehicle. Optimizing it in some way in association with other mods and an informed flash is probably a good thing.

[Dean]

Originally Posted by scoobanader

If there is a lot of hot air in the engine bay shouldn't we do something about it? we can put a FMIC to get rid of heat soke, and we could also put a louvered hood in witch should reliese the engine bay heat very quickly(the faster speeds the better cooling). would the engine bay be cool enough to put an intake on it? there wills till be heat coming off the turbo but it might releise qucik enough not to effect the intake

FMICs are great, but represent quite a significant increase in piping which of course impacts flow.

The fender is probably the coolest area nearby to draw air from, and while I have not put a monometer on it, the fender may actually have a slightly higher than ambient air pressure at speed.

Everything is a trade off... Getting rid of heat is good, increasing drag is not. Properly designing hood vents so they purge heat in static and various dynamic conditions while minimizing drag is not trivial. The Subarus aren't that bad at speed, but like most modern cars, aerodynamics and styling make factory hood vents undesireable, and most aftermarket companies do not have the money for the wind tunnel testing that would be required to actually do a good job.

[qksubi]

Well Matt turned a 230 on the dyno with a drop in and I pulled a 226 with
a ralitek intake :? I simply like to hear the blow off in the car and thats only thing my intake does But mike also with the same drop in pulled a 216 :? Arco gas

[MikeSTI]

Dean - we have the same set-up as the WRX so yes snorkle included

[IheartSTI]

Originally Posted by Dean

FMICs are great, but represent quite a significant increase in piping which of course impacts flow.

The fender is probably the coolest area nearby to draw air from, and while I have not put a monometer on it, the fender may actually have a slightly higher than ambient air pressure at speed.

Everything is a trade off... Getting rid of heat is good, increasing drag is not. Properly designing hood vents so they purge heat in static and various dynamic conditions while minimizing drag is not trivial. The Subarus aren't that bad at speed, but like most modern cars, aerodynamics and styling make factory hood vents undesireable, and most aftermarket companies do not have the money for the wind tunnel testing that would be required to actually do a good job.

Would it be worth going to a FRIC? or would you loose to much flow?

[Dean]

Originally Posted by scoobanader

Would it be worth going to a FRIC? or would you loose to much flow?

FRIC? I'm guessing you meant FMIC, but whatever, it all depends....

I guess we still don't know what your goals are for this car except your wish for 425-500WHP.

Longer path = slower response. Colder charge air = More power.

Bigger turbo = slower response, and more power...

Everything is a trade off. Oh, and it all costs $$$s, so budget is also a consideration.

[IheartSTI]

my ultimate goal is to make a bad ass rode course car, i would like a lot of power out of the hole, so i dont think a big turbo would be to wise. like i said i wanted it to be a rode course car wich means i will need the proper cooling to keep my motor in good condition.

[IheartSTI]

can i do a FMIC with a smaller turbo? would that even out?