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2.0L to 2.5L engine swap in 2002 WRX

105K views 41 replies 19 participants last post by  ranman 
#1 ·
Hello there guys. I am putting a brand new 2.5L STI motor in my 2002 impreza WRX. I am going to go with a Blouch Polka Pickle turbo, because it is a bolt on turbo and a little cheaper than going the perrin roatated way. What size of injectors would you run in this motor. The car is just going to be used for bombing around town, the odd race at the drag strip, and of course blowing the doors off the demestic car (i.e - mustangs and camaro`s lol) I will upgrade the fuel pump forsure, i already have a perrin front mount intercooler, AEM standalone egngine management system, full 3 inch turbo back exhaust, cold air intake. I had a 100 shot nitrous on the 2.0L motor but i will not be running that on this new motor, seeing how thats how i blew it up i think haha. I will just convert the nitrous system into a intercooler fogger. If you have any other upgrades that you would do please let me know. thanks for you help guys! SORSY
 
#3 ·
Also; the actual STi motor swap is going to be a lot more complicated isn't it? I think you need the STi ecu, wiring harness and all sorts of other stuff to swap it, since the STi motor is drive by wire; and your 02 is not. Unless all of this gets overuled by the AEM...
 
#4 ·
I agree with shotta, 850cc will do great for that setup but hes also right about the tranny. You are going to need to do something with it unless its an actual sti motor, then you can just do the easy thing and get an sti tranny. Plus, if it is an actual sti motor the ecu should take care of the rest but you will need all the harnesses. !Thumbs Up
 
#7 ·
I do not think that it is a EJ257 i think it it i just the EJ25 but i am not too sure i pretty new at this, i am having a import custom shop help me along the way with it. is there two different motors ie (EJ25 & EJ257) your help is awesome thanks guys!!
 
#10 ·
The two different motors are the EJ255 (Forester XT, Legacy GT, 06-08 WRX) and the EJ257 (04-08 STi). Unless your heads are busted up though I don't see why you'd swap in a complete EJ255. Most people just use the EJ257's shortblock with the heads from their EJ205 (02-05 WRX) and make a "hybrid"
 
#12 ·
So what your are telling me is that i should just pull the heads off the EJ20 and put them on the new EJ257 block...will i have as much power as a complete EJ257, or what is the advantage to that?? what is the differance between the EJ20 and the EJ257 heads? And what about the wiring if i was to do it that way? would i still keep all the same 2002 wiring harness and not have to worry about changing it over to the 2004 STi harness?
 
#14 ·
The EJ205 heads are pretty good. You can make big numbers with them. Yes, the EJ257 heads are better but swapping those heads into a WRX is a pain. It's a lot more than the wiring harness. As I said, the petals even have to be swapped.
 
#15 ·
1) Stick the WRX heads on the STi block. 2) Stick the STi heads on ebay or something and take the resulting profit and buy yourself something nice. New turbo, etc.

This will same you time and effort and still net you close to the same power. If you spend that profit wisely, more power.
 
#16 ·
Ok well..since i have already ordered this complete new STi crate motor (EJ257) i will just pull my heads off the (EJ20) and put them on the new EJ257 block. Should i still use the same intake off the EJ20 or use the new one off of the EJ257 motor? is there a differance? and once agian since the rings are cooked in my EJ20 should i have the heads looked at before i drop them on the new block? thanks agian guys!!!
 
#18 ·
hey hey guys. i was just going to pull the motor on the car would take the whole front end apart ie fenders grill bumper intercooler, frame supports and just unbolt the trany too and just slide everything out like that? of would you just unbolt the motor from the trany and just go straight up with it?
 
#20 ·
If I threw a rod (horrible knocking sound, low power), should I get a EJ257 short block? I've been wanting an excuse to go 2.5. Anything else I'll need to replace (besides getting a new turbo)? Tranny? Electrical? Has anyone posted a guide to swapping the short block? I figure I'm capable, and I have a neighbor who knows quite a bit about cars. Anyone actually done the hybrid swap?
 
#23 ·
I see this is a old post but I picked up 02 wrx for trade with my truck. He said it was an sti full swap motor and trans. But my engine block says ej20. And it is a 5 speed. But has a sti top mount intercooler and Vf34 turbo not vf39 like he stated and the tuner on it is a Cobbs access port for sti motors with vf39 turbo and car spits real bad and has alot of codes the alleged
Motor swap was from a 04 sti. Can anyone help me verify this? If so I need to know what size inj. Are in the car what the fuel pump puts out and what not so I can get this car tuned properlly before something goes catastrophic and I melt something
 

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#24 ·
The 04 STI comes from the factory with a ej257 2.5 litre engine, 6 speed transmission, 535cc sidefeed injectors, 145 lph fuel pump, and a vf39 turbo. There is no off the shelf cobb map for your mods. As I stated in the other thread, get that car to a tune shop who knows Subaru's ASAP!
 
#25 ·
To be honest that looks like a WRX intercooler painted with the STI logo, or maybe just bad lighting.
Take a few more pics if you could.
Fuel injectors,boost controller and turbo with other engine mods you can see.
Maybe someone will be able to help you a bit.
 
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