wrx versus Sti engine spec
 

I am sure this is a n00b question. However i am curious to know the difference between the engine specs of say a 2003 wrx and an STi. WHat makes the Sti so much more powerfull.

I have what appears to be a wrx engine that has a PPP kit fitted , both for engine, wheels and Brembo Front brake mods. The intercooler is larger than a wrx. The exhaust is an afterburner full exchange system. The pipe coming out of the back of the turbo (just where the heat shiled is ) is massive, must be at least 3.5 inches. Is that normal?

Short of putting the car on a rolling road i am hoping my outputs are close to a standard STI if not slightly higher. ALthough i have service history and PPP certificate, i dnt have any paperwork that shows any other mods. But it was a bonus to discover the car was TrackStar2 fitted and a laser jammer too :)

Cheers! :freak3:

STi has a 6 speed box.

Thanks for that, i was after engine differences, but apprciate your input all the same, cheers! :thumb:

Alot of internal engine changes,suspension,the list goes on.JAY

Engine wise, the STi has stronger internals, a bigger intercooler, no cat in the up pipe and a few other extras. The quoted power is the same for a WRX PPP as an STi though (265bhp), but the STi can be tuned to produce more.

variable valve timing too,but bigger turbo is what mainly makes it go faster :)

Pistons,crank,cams,valves,variable valve timing,turbo,probably heads,bigger clutch,stronger gearbox,suretrac front diff,and lots more.JAY

BluesimonIndeed, my WRX running a VF35 etc recently made more power (followed each other onto PS rollers) than a similarly specced, same MY STI..:D

No doubt that if you were to really push them to their limits the STI lump would maybe last a little longer, maybe not..?

Great thanks for all that info. i had a look underside, i cant see any cat, no doubt in January (MOT) time that will be a problem! However, i think a little trip on a rolling road would be be good, at least i will know my ouputs then. It feels as fast as hell ( at least when the sick MAF is changed ) best fun ive had in ages :lol:

But which engine would you have preffered to have tuned given the choice.JAY

don't for get the jdm sti engine is even better spec'ed than the uk equivalent with stronger internals etc

Bluesimon hits the nail on the dead LOL

STi runs bigger turbo for the power but to make sure there are not so many warrant claims subaru beef up a few components !!

Plenty of people errode the safety margin...I run near on 400 BHP on standard Bugeye internals and gearbox with methanol / water injection :D

Shaun

Ferretboy, you may still have the catalyst downpipe (with bypass pipe from wastegate) thats part of the PPP pack, just the underfloor cat removed.

Simon

stronger internels i.e STi employs either a Closed V deck block or semi closed block, most WRX employ an open deck design . The fully closed block gives the most support to the cylinder which will allow you to run the highest cylinder pressure and is used for higher boost applications . The semi-closed is also stronger than the open deck and are suited for applications that are not extremly high or prolonged. the open deck is the easier of the three to manufacture and cannot support high cylinder pressures hence head gaskets are easily damaged .