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engine swap

16K views 11 replies 6 participants last post by  Drftwell 
#1 ·
I thinking of swapping to a 04 sti 2.5L engine(I currently have a 04 2.0L wrx engine.) that my friend is about to give me basically for free....He is gonna drop a fully built race engine in his sti. How hard is the swap? I would be getting his ecu and everything (including a cobb tuner for it.) It would be a turn key engine with the exception of the tranny. I'm thinking of redoing the gears in my tranny for the swap. or maybe sourcing a STI tranny from some where. any ideas would be helpful as it will probably happen with in the next 6 monthes. What turbo is best for it? 20g or a perrin gtr30 rotated kit? Any and all Ideas welcome...I'm not looking at drag racing with it. I basically want a killer cornering machine for autocross and time attacks and maybe some freeway runs. Help me out guys .Thanks -Big Jay.
 
#2 ·
it will bolt right in... along with the ECU you will need the wire harness from the STI, because it is a little different. the STI has 2 cam position sensors and AVCS. and it is also drive by wire, so you will need everything that goes with that. Its doable but will take alot of work.
 
#3 ·
The swap is fairly easy. The main issue will be drive by wire throttle which also requires pedals from a usdm sti. But you can just keep the intake manifold from your rex or replace a throttle body, or use wrx braket for the throttle cables, and retain your wrx pedals. If you are not upgrading the transmission at the time of the motor swap, you should just keep the stock sti turbo with everything. The power will be amazing right away and not too much extra stress on transmission. If you go even 20g, be prepared for new gears or tranny.
I am not sure on the vacuum lines and fuel lines, but since yours is same year as the donor car, it should all the same.
Hope this helps,
cheers!
 
#6 ·
you can try junkyards, but it will be hard to find a wire harness, I imagine it would be aroud 500 from the dealer, but that is just a guess. i would wait and try to find a harness before i would use 2.0 heads on a 2.5. you want the AVCS
 
#9 ·
sorry to bump this thread but just need some more info.... ok so heres what i have:
ej257 motor complete
engine harness
ecu

all of this will be going into an 02 wrx.... what else am i going to need? i was told that i could just use my stock intake manifold and as long as TPS was hooked up that i wouldnt need to change the pedal..... and if i do have to change the pedal... whats involved in that??? thanks for your time!
 
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