waexplorer Posted August 8, 2018 Share Posted August 8, 2018 I know chamber cc are different. Anything I need to do with them to make them work? Will exhaust timing belt gears bolt on with non AVCS seals etc. I'm using tablet and it won't let me search. I assume I'll need D25 heagaskets. They are 08 STI heads. Link to comment Share on other sites More sharing options...
Max Capacity Posted August 8, 2018 Share Posted August 8, 2018 Hopefully "m sprank" will chime in soon, PM him if he doesn't. "relative4" may know the exact answer too. I know there are things you need to do, but I haven't done this, so I don't really remember what. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
rhino6303 Posted August 9, 2018 Share Posted August 9, 2018 08+ sti heads are W25. Are you sure you have D25 heads? Take a picture and upload it so we can be sure. I don't think W25 heads will be friendly on an 05 shortblock. If they really are D25 then all you need are D25 headgaskets and a new AVCS/Turbo oil supply line. Link to comment Share on other sites More sharing options...
Tehnation Posted August 9, 2018 Share Posted August 9, 2018 https://www.youtube.com/91dc95b4-e7bd-4e07-8f08-4823891d0eb7 The cylinder head volume is different, so your compression ratio will change. That's why the piston dish volumes are different in the ej25 blocks. D25's will work I believe, it's a matter of compression ratio, otherwise I think you just need an air pump delete or some nonsense like that! I just went through this cylinder head piston dish nightmare over on nasioc..... this video helps clear things up. But 08 sti is supposed to be w25 heads like rhino said, so there's a bit of conflict in your post. Either way I think w25's will bolt up as well, I think any turbo cylinder head will bolt up, the cr's just change. Link to comment Share on other sites More sharing options...
waexplorer Posted August 9, 2018 Author Share Posted August 9, 2018 Ok thanks. These heads are for sale on Craigslist. I can't seem to get the seller to tell me what the casting is, D or W (no good photos). I think I'll pass on these and keep looking. Thanks for info. Link to comment Share on other sites More sharing options...
Homemade WRX Posted September 6, 2018 Share Posted September 6, 2018 D25 (started coming on EJ255 engine in 07 IIRC) heads have nicer ports from the factory but a smaller combustion chamber. You're going to be increasing your compression ratio by using the 05 pistons and those heads. Link to comment Share on other sites More sharing options...
Tehnation Posted September 6, 2018 Share Posted September 6, 2018 I hear a little higher cr is actually better. Link to comment Share on other sites More sharing options...
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