The Ultimate EJ18/EJ22 -> EJ25 Swap Thread
Registered User
Joined: Feb 2003
Posts: 68
From: Pa......N. of Phily "Quakertown"
Car Info: 02-04R-STi PPG's FP-Green 391whp
Not to put a new ? in the mix.....or is in in the wrong thred?
But, what is all invalved with a STI EJ257 long block into a 02-03 2.5 RS ( including the STI ECU and harness) I would be using the RS trans till I can afford a STI or custom rebuilt trans. I know and will be keeping in mind that the RS trans will be in danger of busting if I get on it under boost.
Am I correct in thinking its a matter of splicing the two harrnesses togather and or by-passing something?
But, what is all invalved with a STI EJ257 long block into a 02-03 2.5 RS ( including the STI ECU and harness) I would be using the RS trans till I can afford a STI or custom rebuilt trans. I know and will be keeping in mind that the RS trans will be in danger of busting if I get on it under boost.
Am I correct in thinking its a matter of splicing the two harrnesses togather and or by-passing something?
VIP Member
iTrader: (8)
Joined: Nov 2003
Posts: 2,659
From: Okinawa, Japan
Car Info: 1996 STI V3 Type RA
This is the wrong place for that but anyway what is invalved no one knows; however what is involved is rewiring the car, getting a x-member from the STi, STi long block with exhaust manifold, and TBE. Your trans is just as strong as the WRX trans. I would add an LSD to it though. No need for a 6MT for now. As long as you KNOW how to drive the ~240 or so WHP comming from a stock STi engine is not going to destroy your trans. No 7k drops ever though. You probably will need a new stronger clutch though.
Thread Starter
NASIOC Slut
iTrader: (2)
Joined: Nov 2002
Posts: 4,723
From: Roseville, CA
Car Info: 1995 Subaru Impreza 1.8 L
Originally Posted by keirnna
How can you have DOHC with an ecu that is made for SOHC?
Registered User
Joined: Oct 2004
Posts: 271
From: Monticello MN
Car Info: 1996 impreza 60 trim, 8psi 201 whp, 213 tq 200k mi
this is my swap/ hybrid plan...1996 impreza L awd 5 speed 2.2 liter to 2.5/2.2 hybrid. yes i said 2002 2.5 SOHC with 1996 single port 2.2 heads, it will make the comp ratio around 11-1 and im told i can run this basicly without problems. it should make some massive torque! i anyone know any dyno numbers for a swap like this? because i know its been done
VIP Member
iTrader: (8)
Joined: Nov 2003
Posts: 2,659
From: Okinawa, Japan
Car Info: 1996 STI V3 Type RA
Massive torque is not anything under 300 ft lbs at the wheels. I would swap in the whole 2.5 phase 2 sohc engine. You'll get better performance out of that. Or get phase 1 heads and put a phase 2 short block in there. That gives you 11.5:1 CR.
Registered User
iTrader: (12)
Joined: Nov 2002
Posts: 18,369
From: Reno, NV
Car Info: 1993/2000/2001 GF4 mostly red
Originally Posted by keirnna
Or get phase 1 heads and put a phase 2 short block in there. That gives you 11.5:1 CR.
VIP Member
iTrader: (8)
Joined: Nov 2003
Posts: 2,659
From: Okinawa, Japan
Car Info: 1996 STI V3 Type RA
I have no idea, but I know that they aren't DOHC. I doubt that the 2.2 heads flow any better than the Phase 1 2.5 heads, but I could be wrong there. He was saying that it would be 11:1.
Registered User
Joined: Apr 2005
Posts: 2
Originally Posted by RickInLittleElm
I want to add that you do not need to have custom plug wires made to do the ej18-ej25 swap. I did it yesterday(drive in, drive out) in about 8 hours with no parts.
The ej18 (as most of you know) uses an ignitor and coil and the ej 25 uses a unit that combines the two. All you do is unplug the ignitor, and jump the wires coming into the ignitor over to the pins coming out of the ignitor. Ignore the ground wire and remove the ignotor-you will not need it. 2 in, 2 out. Now splice the 2.5 coil connector into the 1.8 harness. Splice in power and the two signal wires and add an eyelet for the ground wire and use the ground point right next to the coil. The 2 signal wires that originally came from the ignitor, now come from the ecu because of the first splice on the ignotor connector. Done.
The whole swap involved only 5 splices. I just trimmed off the ears on the injector connectors and they fit perfectly and clipped in. I used the 1.8 coolant sensors.
If anyone is interested in specifics, ask away.
It was a 95 ej18 to a 01 ej25.
If this info was stated above and I missed it, I apologize.
The ej18 (as most of you know) uses an ignitor and coil and the ej 25 uses a unit that combines the two. All you do is unplug the ignitor, and jump the wires coming into the ignitor over to the pins coming out of the ignitor. Ignore the ground wire and remove the ignotor-you will not need it. 2 in, 2 out. Now splice the 2.5 coil connector into the 1.8 harness. Splice in power and the two signal wires and add an eyelet for the ground wire and use the ground point right next to the coil. The 2 signal wires that originally came from the ignitor, now come from the ecu because of the first splice on the ignotor connector. Done.
The whole swap involved only 5 splices. I just trimmed off the ears on the injector connectors and they fit perfectly and clipped in. I used the 1.8 coolant sensors.
If anyone is interested in specifics, ask away.
It was a 95 ej18 to a 01 ej25.
If this info was stated above and I missed it, I apologize.
Has anyone tried this? what wire going in to the ignitor hooks to what wire coming out of the ignitor? anyone have a diagram?
Registered User
Joined: Oct 2005
Posts: 48
From: In the middle of no where!
Car Info: Impreza 2.0
guys,
I have a 03 EJ20, it's N/A engine (( EJ20 with 120Hp )), and I want more power so what should I do??
I have 2.5 pistons and rings so, is it possible to bore the engine block and make it 2500cc ,if so then would these bolt on my EJ20 crankshaft and rods.
please help me with it cuz if its possblie I ganna do it by next month,
165 Hp would be much better than 120 Hp
I have a 03 EJ20, it's N/A engine (( EJ20 with 120Hp )), and I want more power so what should I do??
I have 2.5 pistons and rings so, is it possible to bore the engine block and make it 2500cc ,if so then would these bolt on my EJ20 crankshaft and rods.
please help me with it cuz if its possblie I ganna do it by next month,
165 Hp would be much better than 120 Hp
Registered User
iTrader: (12)
Joined: Nov 2002
Posts: 18,369
From: Reno, NV
Car Info: 1993/2000/2001 GF4 mostly red
No, you can't put EJ25 pistons into your EJ20, if it's based on the turbo engine as far as bore spacing and block structure and all that. Far easier would be to source an EJ25 or EJ20R and just swap it in, or a turbo motor. Complete swaps are often cheaper and easier than trying to take shortcuts.
Something Custom
iTrader: (9)
Joined: Aug 2003
Posts: 14,505
From: Las Vegas NV
Car Info: 2018 Grand Cherokee Limited Ecodiesel EOC Stage 1
i heard of dropping in a EJ25 in place of my EJ18 and having it run off of the stock 18 ecu. is this possible. will i have any problems running my stock FWD 4EAT?
Registered User
iTrader: (12)
Joined: Nov 2002
Posts: 18,369
From: Reno, NV
Car Info: 1993/2000/2001 GF4 mostly red
It's possible, but it won't run as well as it would with the EJ25 harness and ECU. You will lose a little fuel economy and power, but it will still be an improvement over the EJ18.