Is a 2008 WRX Turbo short block interchangable with a 2007 WRX turbo short block ?

[FFRSpec72]

If I have a 2008 WRX Turbo short block can I interchange that with the rest of my 2007 WRX Turbo engine parts

[Rasmus]

I believe it'll bolt right up. No issues. Your 2007 heads and ecu shouldn't have any problems running on a 2008 short block.

[FFRSpec72]

I believe it'll bolt right up. No issues. Your 2007 heads and ecu shouldn't have any problems running on a 2008 short block.

So I gather the cases are identical (the '07 is a EJ255 and the '08 is a EJ257), the pistons are different and will add to the C/R and thus not sure how they would match to the EJ55 heads

[D K]

WRX blocks are 255

Check the casting number, but otherwise yes.

[Mechie3]

Sort of related, but I'm running 09 WRX heads on my 06 shortblock (purchased new in 2010). The heads are D25 heads, so I would assume the blocks are EJ255 as EJ257 blocks on B25 heads would make for high compression.

[D K]

Short blocks are the same.
WRX heads are 50cc, STI is 57cc

[BrandonDrums]

Short blocks are the same.
WRX heads are 50cc, STI is 57cc

There is a slight difference in Pistons between the EJ255 and EJ257 but nothing worth worrying about. This thread (too bad the picture links have expired) explains the differences which really comes down to a very slight difference in the dish shape.
http://forums.nasioc.com/forums/show....php?t=1667168

Heads vary more from year to year, there are many different versions of EJ257 and EJ255 heads. The long short of it though is that if you have a set of matched heads from either a 255 or 257 and want to use it with a 255 shortblock or 257 shortblock you're fine. They will bolt right up and not cause any major issues as long as you're getting a custom tune.

No matter what combination you run, it will change areas in the rev band where knock conditions are more sensitive due to different shapes in the combustion chambers and different compression ratios so you'll need a custom tune rather than an off the shelf map.