Max Bridle

Hi all! Max here from Australia.
Recently i purchased a 1998 Subaru WRX. I had intentions of turning it into a race car, over a period of 2 months it took shape into the car it is today. i have only driven it twice at the local autocross(Gravel) and it is outstandingly fast compared to my old race car(Datsun 510) but i have came to realize that it has a noticeable amount of lag when at low rpm, the track is tight and windy and im in 2nd gear the whole way, i cant downshift as i wouldn't carry enough speed in a lower gear. I asked around about the lag and found out it is very common in my model Subaru to have a bit of lag and was told that a cheap and easy option would be to fit a smaller turbo to the car so it would spool easier and be on boost earlier. So i did a bit of research and found out that apparently pre 98 WRX's had larger turbos than newer models hence the large amount of lag in my car. I have installed an atmospheric blow off valve already which didn't do much and around the track im having to quickly pop the clutch to build up boost but of course this is costing me time on the track.So this brings me to my questions:

What options do i have to reduce lag?

Will a turbo off a later model WRX be a straight bolt on to a 1998 manifold?

Am i correct that later model turbo's were smaller?

Any other suggestions and any answers are greatly appreciated
Cheers, Max. car has a few minor things changed but thats the basic style of it

Max Bridle

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Infected by sti

iTrader: (6)

If you want to reain spool, why would you fit a bov surely you would have been better off leaving the recirc on there.

When considering the turbo change keep in mind the mapping side of things that go with it as you wont be making the best of anything if you just add parts an not sorting the ecu to perform at its best.

Max Bridle

I heard a blow off valve would release all the pressure so the turbo wouldnt be pushing air into a closed throttle body causing it to slow down? im new to this so i dont know much if my terms are wrong by spool i meant the turbo winding up thanks for your help

d4vidh

Your best option is to make the car breathe better. Better flowing exhaust system, panel filter and a remap. Although the 98 Impreza has a pretty locked down ecu as far as I know so you would need either an ESL daughterboard fitted or a stand alone ecu which would be expensive.

Infected by sti

iTrader: (6)

You will see better spool with a decent uppipe as well, something like a harvey smith item will see you around 500rpm drop in spool time with a set of ported headers also increasing your torque level, they have been tested and are a well know setup on here with great comments and results what turbo is currently on your car any ideas? Also a lightened flywheel helps through the rev range

Max Bridle

Hi guys, thanks for the quick and helpfull responces! Allready the exhaust is a decat and has 1 straight through muffler. Im taking it that the up pipe is from the heads to the turbo? if i were to remove the mufflers in the section from the heads to the turbo would this help? im not sure what turbo is on the car, all i can tell you is its factory and i think the motor is an EJ20? thanks for the info guys One other question, If i were to bolt a smaller turbo on the car, why do i need to change the computer settings? and does anyone know if a turbo off a later model WRX is smaller?

Max Bridle

Sorry for the silly questions, im only just learning about the subaru scene in the last few months

d4vidh

If you go full decat without remapping you run the risk of overboost (not good)