i bought a set of new alum. 6.0 heads which are supposed to be the same as ls6 heads. they don't really look that much different than the 5.3s but i know they are if they are that much better. so what's the difference? and what is the signifigance(sp?) of the "D" shapped exhaust port? isn't the combustion chamber 73cc in the 6.0 heads? what is the comp ratio on a 4.030" bore stock stroke motor with the 6.0 head?
thanks

 

The combustion chamber volume in the LS6 head shows 64.45cc. The 2002+ LQ9 aluminum head shows 71.06cc. This is going to drop compression in a stock car to about 9-9.5:1 which is very popular for big F/I setups. The D-shaped port was supposed to be a better flowing design than an LS1 head, that's all. Is it really? Who knows?

 

so, if it lowers the compression a half point on a stock cube motor what will it make compression on the 370 4.030" bore stock stroke motor? are you saying you think they are full of it as far as the d shaped port flowing better?