NotoriousREV

Currently running a MY93 WRX with full Scoobysport exhaust (turbo back), HKS induction and ScoobyECU which made 273bhp @ 6355 237lb/ft @ 5750 at Well Lane. I'm more than happy with the top end power (although obviously I'd like more ) but I'm more interested in improving driveability.

The car does feel a little laggy and the turbo doesn't really get going till about 4000 rpm at which point it picks up very quickly.

What kind of things improve spool up?

My future plans were to add uprated fuel pump, bigger injectors (not sure between 440's and 550's), FMIC (or STi 5 top mount at the very least) but I know these will add to top end power, but will they improve or worsen mid-range?

Is it possible to build a 300bhp/300lb/ft 2.0L motor?

Or should I sack it off and buy a USDM 2.5 STi short block and go for a very torquey 350bhp? (I can't afford it, so don't sugget it )

shiper

mines a 95 uk but pulls full boost at 3000. I think it helped with a racing dawes fitted.

NotoriousREV

oops, forgot to mention, I have a "Dawes-like" device already fitted which has definately improved spool up.

hades

Fit a smaller turbo. With a 01+ TD04 you can get up to ~300bhp with 1 bar boost around 2700rpm! More serious options might be something like an MD304 (capable of more power than a TD04), or just a front entry TD05 (capable of >400bhp with 20G wheel). I think your car will have a TD05 (though I may be wrong), so getting that converted to front entry would be a good option. As a general rule with turbos, higher power potential = slower spool up.

There are people running 2.0L at well over 400bhp, 300 should be no problem.

NotoriousREV

I have thought about the front entry conversion (once my fuelling and intercooling are up to a reasonable standard), but will this reduce or increase lag (or make no difference?)

Presumably, spool up is more affected by changes made on the exhaust side rather than intake side? Maybe ported headers and a freer flowing up pipe would help?

Pavlo

I have been in some early cars which may 1 bar at around 3200 with std turbo (90º inlet) while others take a little longer.

Up-pipe, ported headers, non leaking BOV, decent actuator spring, front entry turbo, good ignition strength will all help.

Exhaust heat also makes a big difference, 4000rpm from cold can quickly turn into 3400rpm when hot, so do make sure.

Paul

NotoriousREV

By decent actuator spring, do you mean standard spring in good condition or different spring?

Pavlo

I mean one that is set up properly, with a sensible about of preload, and doesn't have a weak aging spring.

Paul