My Super Build

[RallyBob]

Originally Posted by Giugiaro

i am not looking to max the turbos rather rely more on the valvetrain mod and less on them. I am planning to go up to 550hp rather than 550whp with those turbos.

Okay, if your goal is 550 hp or less they will certainly do the job. However I still believe they really are too small for the engine, and especially for the rpm potential that cams and headwork would provide.

I've been in some WRX's that were pushing the stock TD04 near it's limits. Response is awesome as you'd expect, but the engine peaks very early and has no top end power to speak of due to the heat buildup (inefficient turbine flow) and boost drop in the upper gears (usually 19 psi in 1st gear dropping off to 15-16 psi in the upper gears). Basically I'd expect you to have to shift at 5500 rpms or so regardless of cams and headwork, it will just fall off like a rock on the top end so no use revving it that high.

Maybe consider some VF39's instead? You can get these off STI's pretty readily and cheaply. I've seen STI's making 340-350 whp and 440 w/torque with stock VF39 turbos. That would put you near 700 with your buildup at the appropriate boost levels.

Just a thought anyway.