legacycentral bbs

I was wondering what I need to do to reach 500hp with my motor,I have obtained a t3/t4 combo off a 2006 ram. I have seen this work on a stock 2002 wrx 2.0 liter. I know about the pistons, connecting rods, crank, but what about the stock heads? I dont know how much they can flow. I am willing to swap it all for newer heads, manifold and wiring, but only if necessary......

i personally dont think its gonna happen. im in the process of trying to get 350hp and 350tq out of my stock heads after some work to them. but 4-500hp... hmm, i dont think so but i could be wrong.

Short answer would be..... no.

I am/was making 420 whp with t3/t4 @ 26-28 psi on E85 with 97 EG20R heads....with 2.5 liters to boot....

The heads are the reason for the good low end power, but the also run out of steam at 5500 rpms.
I am at 225/250 ATW with stock heads and a good turbo and management, but the heads and the intercooler are the last restrictive factors.

You can make that much crank horsepower, but you need a good sized turbo to do it, among other things. OK, many other things.

I was making around 300whp with a 47 lb/min turbo (GT2871R 56 Trim) at 21 psi. Delta 220 cams, and lots and lots of supporting mods.


IMHO, you would have an easier time fulfilling that kind of goal with other head options.

Thats good info, I found some 2.5 wrx heads brand new , never used for $500. worth it?

Depends on what all the heads come with if they are bare heads I'd never buy them for $500.

obd1-kenobe wrote:I have obtained a t3/t4 combo off a 2006 ram.

If that was a diesel Ram, it's not a T3/T4...more like a Holset HE351

thats what a he351 is isnt it? t3 exhaust, t4 compressor? The heads are complete with cams valve covers and brand new from subaru. Factory sti lash.

Newer heads ('02+) cannot be used with any of the earlier ECUs, including anything that work in our Legacies. The cam pickups are different. You would need to convert/swap/merge to a compatable ECU/harness.

There has been talk of custom cam gears to fix this problem, but nobody has done it yet.

Now that this info has come to my attention..........I already own and plan on running a 2002 Sti spec c computer w/turbo xs 6 stage tuner, all 2002 sti intake and wiring harness, this will solve my fuel injectors, throttle body clearance from firewall will be better, allowing me to fit the huge holset. and obviously allowing the mate for the new heads......and all the sensors......But ur saying I need 2002 specific sti heads? Should I just buy cosworth heads?

Throttle body clearance doesn't really have anything to do with how large of a turbo you can fit in the engine bay.

If your running a GD/GG+ ECU and harness you will need GD/GG+ heads. I would look to V7/V8 heads.

For that particular project the traditional Subaru boards will have better info relating to the motor and ECU. Note that your chosen ECU is AVCS and cable throttle, a combo that never came to North America. So you will be dealing with JDM parts mostly.