Need Advise! Engine swap from DOHC to SOHC

[WESTcoast]

Im on the verge of buying a ej25 SOHC engine to replace my engine with a burnt valve. I will be getting it from a friend who replaced her's with a 07sti engine and drivetrain so she did it for the hell of it.

My question is swapping it from my DOHC platform what will be some hurdles I will run into and if you have solutions for those hurdles that would be awesome too!

Some that I came up with are

-will i need the ecu or can i use mine
-what will i do about the maf to map situation
-what will hook up and what wont
-what will i run into?

Thanks in advance!

[RS MN]

edited.


listen to that guy \/ :smt023

[mike-tracy]

^^
EJ25D's have only 1 cam position sensor. The EG33 has 2.


While researching putting an EJ251 into my EJ22-based Impreza, I read people could run the SOHC motor with the stock ECU, changing the cam sprockets to those from an EJ18 will let the engine run. I know an EJ22 ECU plugs in to the EJ25D wiring harness, so my "educated" theory is that you could run the EJ25 sohc with the 1.8L cam sprockets, and the fuel injectors, sensors and engine wiring harness from the EJ25D, and either the EJ25D or EJ22E ecu (I have ran both ecu's on both motors - but not on EJ251's). Since the ECU remains MAF based, you shouldn't have to mess with anything else.

My research came from RS25 and Ultimatesubaru forums.

[RS MN]

i read the OP wrong lol. and found out i knew less about the 25d than i thought i knew lol.

thanks mike-tracy!

[WESTcoast]

haha alright sorta lost mike after you said cam sprokets lol and im dizzy lookinat RS MN's bird gif lol.......im guessing what you wrote goes for what rs put on his post but since he edited i have no clue lol

a whopping 200 bucks buys me
-engine
-full rs drivetrain (going to use some tidbits off of it but the rest will be for sale)
-ecu
-what ever else i can i can fit into the truck of my outback :)

so if needed i can get the sohc ecu :)

[mike-tracy]

For that price definitely buy it, but I highly recommend doing some research of people who have actually done the swap.

There may be some differences that result in CEL's (ie, if you run an EJ25D ecu and it's looking for an EGR port, etc). I am positive the EJ251 ECU isn't compatible with the EJ25D wiring harness.

Also I wish I was closer - I'd buy the transmission assuming it's a 5mt.

[WESTcoast]

yup its an 5mt tranny with RA gears :D

[RS MN]

haha alright sorta lost mike after you said cam sprokets lol and im dizzy lookinat RS MN's bird gif lol.......im guessing what you wrote goes for what rs put on his post but since he edited i have no clue lol

a whopping 200 bucks buys me
-engine
-full rs drivetrain (going to use some tidbits off of it but the rest will be for sale)
-ecu
-what ever else i can i can fit into the truck of my outback :)

so if needed i can get the sohc ecu :)


off topic, but are you getting the rear diff with the full drivetrain?
i'd like to buy it from you if you dont need or want it.


and honestly, my post wouldve been of no help to you lol. i read your post wrong, and also over estimated my understanding of the DOHC engine & ECU you are replacing

[RS MN]

oh i didnt see that it was RA, is it still 4.11 FDR?