[ichitaka05]

Originally Posted by old greg

I see three possiblilites.

1) It'll be a destroked/bored FB like we were talking about, with slightly different heads. A 72mm stroke is a pipe dream though IMO, it won't be lower than the EJ20's 75mm stroke as Subaru is looking for higher torque/fuel economy.

On the plus side, they may want to stay away from the asymmetrical rods on their boosted engines which would keep stroke reasonable. ~80mm seems likely (ej25 = 79mm), and is plenty low for some very high rpms. Remember that the F20c had a stroke of 84mm and revved to 9000 rpm.

With the same deck height as an FB20, an 80mm stroke would allow 134.3mm rods. At 8000rpm that means a mean piston speed of 4200 ft/min and peak piston acceleration of 3718 g, which ought to be fairly reliable (compare that to 4724 ft/min and 4344 g for a normal FB20).

Figure a forged bottom end (that's just how Subaru rolls), probably a semi-closed deck, with forged pistons in the STi and cast in the WRX.

2) Something similar to #1 but with 2.5L, ~85mm stroke

3) They go for max. displacement. The FB kept the 113mm bore pitch of the EJ, which means that there should be enough room for a 99.5mm bore (EJ25). At 99.5mmx90mm we get a 2.8L engine. This doesn't seem all that likely with the CAFE deadline coming, but you never know.

Sorry, call me "jackass", "too damn picky" or whatever you want... but it's STI now and not STi anymore.

The Subaru Impreza WRX also comes in a high performance STI edition (formerly designated "STi" before the 2006 model year), designed by STI

http://en.wikipedia.org/wiki/Subaru_..._International

Sorry for off topic, but it really bugs me when I see that.