M.R.90

having just bought 2.2 audi 90 10v, want more power. is it possible to swap 20v head onto 10v block if so is it worth doing.is there any other mods worth doing?

Tony Hoffman-4000Q

Not really a bolt on fit. On a 4-valve engine, most of the combustion chamber is in the head. On a 2-valve, it's split in the dished pistons and the head. If you put a 4-valve head on a 2-valve bottom end, you end up with something like a 6:1 compression ratio. Not sure if it would run, but you definately would lack some serious torque. A stock 4-v engine is about 10.5:1.

In addition, I'm not sure how you would go about working out the fueling. The 20V is electronic, the 10V is CIS.

Tony Hoffman