The Toyota Corolla even Yaris has Dual OverHead Cam, comes standard. On the non-turbo Subaru is it is SOHC.Why can not they use DOHC?l like the Legacy 2.5i, but since it is SOHC, is it slow? or does it have good pick-up?

Subaru switched back & forth several times. In the end especially on non turbo models they found that the gains from a DOHC setup were basically offset by the losses to additional rotating mass etc & unnecessary complexity. Also a DOHC boxter motor requires 4 camshafts instead of 2 like an inline engine. Back when they started selling the ''sportier but still not a wrx'' 2.5 RS they were DOHC for a year or two & then went back to SOHC without any real change in the power of the motor. Heck the new corvettes r killer fast & they have a single not overhead cam & they do fine. DOHC in & of itself does not really make that much extra power, its just easier to build a 4 valve per cylinder engine with opposing pairs of valves with 2 cams instead of one.

DOHC cost a lot more than SOHC. The Legacy 2.5i is not slow, and is cheaper to insure. Very good car.

DOHC and SOHC have nothing to do with speed really. It is a twin cam engine (being a boxer), so its the same as having a DOHC inline engine. Having DOHC on a 2 headed engine means four cams, which adds a ton of rotating mass, for really no gain (especially on a 4 cyl car).

y2whateverhisnameis (the first poster) was spot on.

The DOHC is available in the 3 litre H-6. It used to be available in the 2.5 H-4 in the mid 90's. My 93 Legacy is a 2.2 H-4 DOHC. The 2.i SOHC is excellent. It is not slow has very good pick up, a nice ride and great handling. It is 173 HP. The 2008 Legacy will come with the optional 3 litre DOHC H-6 engine. The 2.5 SOHC is a powerful engine that delivers well especially in the Impreza.

l had a 2.5i and quickly passed this car on to my (*adult*) daughter and got the 3.0 H-6. l felt the 2.5i was kind of slow on merging or getting out of stop signs. 0-60 is around 10 seconds with an automatic transmission. My new car is not a WHOLE lot better - maybe under 8 seconds - but it seems to have more right off the line than the 4-cyl has.

there is a few resons for subaru not to make a dohc engine.

firstly it is allready a fery tight squese where the heads r on the engine it would be very hard to fit another two cams (one for each head).

secondly, at the moment the heads r allready running 16 valve system. there isnt much point adding an extra cam for one extra valve per cylinder. u wouldnt even get much power in it.

the only reson u would really want a dohc on the subaru motor (example the EJ22) would be for more power. if u want the pewer simply go for the turbo. or get the sti heads installed.