Different heads on 2.5?

[anwieczo]

I have heard of people doing this on other forums and was wondering is it possible to interchange heads on different Subaru motors? For example could I put EJ22t heads on my DOHC EJ25? Please understand I am a noob and if this seems like a stupid question bare with me...

[RedEvilWgn]

When I was down at subie tech training (im a dealer technician) the class and teachers talked about swapping heads on single cam blocks, such as 2.2s on 2.5 SOHCs and whatnot (a guy built a 2.2 with 1.8 heads lol)....

....if you like I can ask around the shop tomorrow.

[jey]

Yes, they bolt right up, heads and shortblock are interchangeable.

[anwieczo]

Are there any advantages to doing this?

[RedEvilWgn]

eh.....

well anytime you put heads from a smaller engine on a bigger liter block you'll get a bump in compression.

A friend of mine just put together a 2.5 sti block with 2.0L heads and it bumped his compression up a bit.

just remember to use the headgaskets that go with the block, not the heads.

i'm sure i'm forgetting something else....

[jey]

Are there any advantages to doing this?

Certain heads flow better than others. We swapped on EJ25 heads for the turbo motor project because they flow a lot better than my EJ22 NA heads. Not sure how it compares to the EJ22T though, but I'm making decent power out of the EJ25 heads.

Other factors to consider when chosing heads is what kind of rpms you'll be seeing in your build - and whether your valvetrain components are up to it. But if you're at that point you're probably upgrading your valvetrain stuff anyway.