Quote Originally Posted by midnight04 View Post
Due to the forced induction from the turbo's you have to run a lower combustion rat. if not you can burn a hole in the pistons cramming all that extra air down in to the pistons causes the need for more combustion chamber area for all that extra air...
I think that's the layman terms on it....Im sure there are more technical terms and explanations for it.
Not necessarily...you wanna lower compression if your gonna run HIGH boost numbers...like 20+psi. As far as I know there is nothing wrong with throwing 10-15psi on a motor with 10.5:1 compression.