Topic: FAQ: What supporting mods do I need for (x) turbo on my car?

[jer]

Turbo upgrades are a very common upgrade on the WRX and STi. It seems everytime you turn around someone has upgraded their setup and has their OEM turbo for sale. With PLENTY of "will it fit" threads and PMs flying around I thought maybe it'd be a good idea to have a "known upgrades needed" list. I'll start it off with what I know and then others can chime in and I'll add it all to this post.


WRX
02-05 - OEM 2.0L TD04L
VF-30 - injectors(min 565cc), fuel pump(min 255lph), up pipe, and downpipe (required) + TMIC (recommended)
VF-34 - injectors(min 565cc), fuel pump(min 255lph), up pipe, and downpipe (required) + TMIC (recommended)
VF-39 - injectors(min 565cc), fuel pump(min 255lph), up pipe, and downpipe (required) + TMIC (recommended)
06-07 - OEM 2.5L TD04L
VF-30 -  downpipe (required) + TMIC (recommended)
VF-34 -  downpipe (required) + TMIC (recommended)
VF-39 -  downpipe (required) + TMIC (recommended)
VF-43 -  downpipe (required) + TMIC (recommended)
08-09 - OEM 2.5L TD04L
09(265) - OEM 2.5L VF52



STi
04-05
18G-20g - injectors (min 750cc) (required)
FP Green - injectors (min 850cc) (required)
FP Red - injectors (min 850cc) (required)
06-07
18G-20g - injectors (min 750cc) (required)
FP Green - injectors (min 850cc) (required)
FP Red - injectors (min 850cc) (required)
08-09
Notes

More air needs more fuel
Higher boost means more heat so more cooling is a good idea
Change a power related part FORWARD of your final catalytic converter and a tune ASAP is a really, really good idea.  Its amazing what our cars will run on, but just because its running doesn't mean it should be driven.

If anyone knows the minimum or recommended specs on injectors, fuel pumps, tmics, etc. if they could let me know and I'll add that info as well.

[mars636]

Hey Jer,  02-05 WRX Minimum injector size for those turbos should be 565,  The 06-07 wrx should not need any injector or fuel pump upgrade for the turbos you have listed they already come with 565 injectors. And the uppipe on the 06-07 wrx should also be good enough as it is already catless.

[jer]

...And the uppipe on the 06-07 wrx should also be good enough as it is already catless.

I knew that

[jer]

255 for the fuel pump on the 2.0L WRX's???

[TWRC]

Yes, you will need 255Lph on a 2.0L, not that I'm looking into it. 

[karainthewrx]

Thanks Jer for the thread! It's good to have this knowledge because I've actually wondered...

Thanks guys

[BradM]

The 09 265 is a VF52 sti leggy hybrid (leggy hotside sti cold? I think)

[Jitenshakun]

You don't actually "need" a downpipe.  Its clearly a good idea, but it isn't necessary.  Similarly, an UP is a good idea, but isn't required for those turbos.

For STis 18G-20g 750cc, Green/Red 850cc and bigger means 1000cc injectors.  Of course these can scale down with water injection.

There are some pretty hard rules.  I.e. if running more than 24psi you'll need a new MAP sensor if you want fuel cut safety and the ability to tune north of 24psi.  I think that at those numbers you'll also need a big MAF sensor as you'll max out your stocker. 

I think its admirable to try and say you need this if you do this, but there are so many variables its tough to say.  Clearly, more air requires more fuel but apart from going "really" big a lot of the "necessary" mods really aren't that necessary.

Here's some simple rules

More air needs more fuel
Higher boost means more heat so more cooling is a good idea
Change a power related part FORWARD of your final catalytic converter and a tune ASAP is a really, really good idea.  Its amazing what our cars will run on, but just because its running doesn't mean it should be driven.

 

[darkrid3r]

This is awesome make it sticky.

[jer]

You don't actually "need" a downpipe.  Its clearly a good idea, but it isn't necessary.  Similarly, an UP is a good idea, but isn't required for those turbos.

I don't agree. Would *you* put a VF34 on a 2L WRX with just injectors and a fuel pump? I seriously doubt Sunny or any other respectable tuner would want to touch it. Maybe Sunny can comment on this?

There are some pretty hard rules.  I.e. if running more than 24psi you'll need a new MAP sensor if you want fuel cut safety and the ability to tune north of 24psi.  I think that at those numbers you'll also need a big MAF sensor as you'll max out your stocker. 

I think its admirable to try and say you need this if you do this, but there are so many variables its tough to say.  Clearly, more air requires more fuel but apart from going "really" big a lot of the "necessary" mods really aren't that necessary.

Well obviously if you're going for insane boost/power you should be asking your tuner what you need on top of the base supporting mods. The idea here is to have a starting point for a turbo upgrade. example:

"I wanna upgrade my turbo but I don't wanna touch injectors, what can I use?"

[darkrid3r]

Jer,

Thats a great idea, keep it simple, but show the support mods for monster power too. This way some  of us not so car smart guys can have a clear upgrade path based on turbo size and or parts recommendations.

I was thinking of ryans domIII but i think it would mess my tranny the way i drive. This list would be even better if we could put in things like, if you go this big on this car, these may be the results, like a stripped second gear

[jer]

Jer,

Thats a great idea, keep it simple, but show the support mods for monster power too. This way some  of us not so car smart guys can have a clear upgrade path based on turbo size and or parts recommendations.

I was thinking of ryans domIII but i think it would mess my tranny the way i drive. This list would be even better if we could put in things like, if you go this big on this car, these may be the results, like a stripped second gear

that's the idea behind the "required" and "recommended" points. I'm going to refine the list when I get a chance so it reads a bit better.

[Cyni]

I wonder what the most power pushed through a stock WRX catback has been to date... Really interested in how a larger turbo performs when pushed through a stock exhaust (aftermarket downpipe), to keep the quiet nature of the vehicle intact.

Silent rocket... I guess i'm getting old


As for the '08's... The only bolt-on turbos are the VF40 and VF46 (no other mods required at all), and the VF52, with which it is suggested that you upgrade both the TMIC, and Downpipe.

All other turbo's require pretty extensive modifications to make work.  (Intake Manifold, Throttle Body, FMIC with STi connectors, etc.).

[BradM]

All other turbo's require pretty extensive modifications to make work.  (Intake Manifold, Throttle Body, FMIC with STi connectors, etc.).

This is not true, the 08+ wrx does have other bolt-on turbo's as it is a shared platform with the 05+ leggy, AVO makes some very nice direct bolt-on's:

http://www.avoturboworld.com/avoshop/index.php?cPath=267_210_212

[Cyni]

My mistake, completely forgot about the AVO turbos.

Pretty sure that with any of them, you'd require a TMIC, Downpipe, Injectors and Fuel Pump.

[Airboy]

The point to swapping out the turbo to a larger one would be to push more air and generate more power.  You can get more power if you free up the exhaust, even with the stock turbo (aka stage2).  To put in a larger turbo without uncorking the exhaust first would make no sense.  The 2L WRX has 3 catalytic converters in the exhaust path, with one sitting in front of the turbo.

I have tried to tune a 2L WRX with a 18G turbo with the stock exhaust (UP, TBE).  Emphasis on the word "tried".

[Cyni]

In my example though, the car would have zero cats Sunny.  The aftermarket downpipe would remove the last two (or replace with a high flow cat), which would remove most of the restriction would it not?  Just wondering what the most power you could shove through the stock catback is, or what has been done. 

[mars636]

255 for the fuel pump on the 2.0L WRX's???

nope you dont need a fuel pump for a vf34. I have had my vf34 for a few years now with the stock fuel pump and no problems.  I guess it should be recommeded but not required.