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2003 ej251 into 2009 ej253 car? - Updated!

2477 Views 2 Replies 1 Participant Last post by  philosophical
HI, I Haven't been on the forums for a long time, but I have a new to me forester that I need to get on the road and I am looking for some help.

I have an 03 forester with a rebuilt ej251 engine that only has 25000km on it and runs great. The body is rotten though and it needs to go.

So I recently picked up an 09 forester for $900 with a blown motor which uses the newer ej253 and has avls. my hope is that I can use the long block from my 03 and somehow disable the avls system in the ecu, or maybe swap the heads over from the 09 if they aren't ruined.

I cant find anyone that has done this particular swap, probably because nobody wants to put an older engine in a newer car, but my older engine is in great shape, the heads have even had a 3 angle valve job and a port\polish done on them.

I am also concerned that if I swap the newer heads onto my older motor, it might lower the compression since the newer pistons are semi domed and the older ones are basically flat top.

any help is appreciated!
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Upon further inspection of the pistons, it appears that the compression would likely be the same between pistons since the older ones are flat, and the newer ones are dished in the middle, but domed on the outside to make up for it. the problem is that the pistons in the avls motor have a deeper dish in them to allow the higher lift valves to clear the pistons, so im almost certain that the valves would end up hitting the pistons when avls engaged if I just swap the heads over.

In further news, I think the heads off the car i picked up are likely trash as the oil pump has a lot of pitting in it which I didn't notice until I cleaned it up, so I either need to swap the entire ej251 which I dont think is possible due to the missing avls, or pick up a complete motor.

the other option is to buy ej253 pistons and heads, swap those into the ej251 short block and re-assemble. I dont really think its worthwile though, I would probably be better off just selling the old motor and buying a complete ej253.
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I ended up picking up a jdm ej253 and i am in the process of swapping it in.
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