Thread: Pistons
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#14: 02-06-2013, 10:20 AM
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Title: Flying W00t Monkey
Location: Rhode Island
Car: 2015 CBS WRX, 2010 LGT (retired)
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Originally Posted by fahr_side View Post
No, the '10~ pistons are different. As I understand it the new heads have a chamber volume similar to previous models but with dual AVCS added. They're not the same heads as the GRB EJ257 ('08~ STi).

Therefore, the dish volume has to be smaller to come up with the higher compression ratio. I don't know if anything is different.
Didn't have an opportunity to post this sooner.

Yes, the pistons are different for the 2010-12 LGT. The crown shape of the piston head has been modified.

For the heads, slight changes. The combustion chamber has been modified. Cam timing changes for low range TQ; valve springs are different as well.

(Interesting that for the 2.5i non-turbo, the heads were changed to improve cooling and the pistons changed (shape and 26 gram weight reduction)
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fahr_side (02-06-2013)