yardie Posted July 18, 2013 Share Posted July 18, 2013 This is correct, as long as you use stock compression ratio with each head (stock wrx with B25, stock LGT with D25) you won't run into problems. When you start getting away from stock piston CR though reliability and fueling options come into play. If your CR is too high pump gas will ruin the engine. Man where all you head gurus a month ago when I was trying to swap B25 and D25 heads? I was following your thread and was glad you got back the D25 heads instead of trying to work with the B25's although I could've learned from your experience Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted July 19, 2013 Author Moderators Share Posted July 19, 2013 so to rehash, d25 and b25 heads will both be fine on either a 255 or 257 shortblock--but when choosing pistons you should match the CR of the pistons to the stock CR of the heads being used...? "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted July 19, 2013 Author Moderators Share Posted July 19, 2013 also, what's the story on 2.5i engines? Anything transferable in terms of short block and/or heads? I'm guessing no on the heads since they would be SOHC. "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
I Donated thefultonhow Posted July 19, 2013 I Donated Share Posted July 19, 2013 also, what's the story on 2.5i engines? Anything transferable in terms of short block and/or heads? I'm guessing no on the heads since they would be SOHC. The intake manifold is apparently transferable. Nothing in the actual longblock, though. Link to comment Share on other sites More sharing options...
Max Capacity Posted July 20, 2013 Share Posted July 20, 2013 also, what's the story on 2.5i engines? Anything transferable in terms of short block and/or heads? I'm guessing no on the heads since they would be SOHC. Why would you even ask that....lol If you raise compression you should have the car tuned to make sure all is good. The high the C/R the easy you get knock. 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...
Max Capacity Posted July 20, 2013 Share Posted July 20, 2013 so to rehash, d25 and b25 heads will both be fine on either a 255 or 257 shortblock--but when choosing pistons you should match the CR of the pistons to the stock CR of the heads being used...? I'm no expert, but sounds like the CP's are a better fit for the D25 heads. You seem to havea clue so if you went with a little higher C/R you know enough to get a proper tune. 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...
Moderators BarManBean Posted July 20, 2013 Author Moderators Share Posted July 20, 2013 I ask because I don't know! Trust me, I'm well aware that I literally know just enough at this point to be extremely dangerous, lol. Also, you should know that if I were to ever put a new engine (new, rebuilt, whatever) into one of my cars I would definitely have it tuned--probably because it would also be modded I also ask because at the moment I have nothing but time. I'm in no need for building an engine, I'm just exploring the possibility (and I WILL be playing with a shortblock at the very least, already paid for that one). Basically if I can pick up parts here and there and piece things together it not impossible for me--hence the question about 2.5i stuff--if I can scavenge certain parts and get them for dirt cheap, why not? Whatever I do, I'm going to do it for as cheap as possible, but that the same time I will be building the engine as if it will go into my own vehicle so I'll spend money where needed. For all the stuff that I can find used or for cheap though, I'm happy to wait for the classified markets to come through "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
Max Capacity Posted July 20, 2013 Share Posted July 20, 2013 Boy aren't we a little testy this AM, didn't you eat yet...LOL I know the feeling of knowing enough to be dangerous, I'm learning a new testing process here at work. Making H2 and O2, I can be very dangerous. LOL Good thread tho...I've learned from it. 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...
Moderators BarManBean Posted July 20, 2013 Author Moderators Share Posted July 20, 2013 testy? I'm not testy? How dare you!?! "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
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