Hey guys i have an engine being built at the moment and am thinking about changing my original plan. The motor is an LQ4 4.060 bore 4.0 stroke. The rotating assembly has diamond pistons that will put the cr around 11:1 with my 317 heads. My engine builder is supposed to be extremely good with porting and I cannot decide if these heads will make good power ported or if I should just bolt on a set of cnc L92 heads from sdpc. I was hoping for around 600HP N/A with this combo but am unsure if it is possible with a streetable cam. Please Help

 

I'd go with ported LS3, L92's solid intake valves are pretty heavy and harder to control vs LS3 hollow stem intake valves.

 

A cnc job is only as good as the hand port job it was designed after;even those can be improved on too. At a point its splitting hairs imo
You have to screw up pretty bad to do an inconsistent hand port or maybe just starting out and miss some things. Let him do his magic can he quantify the results?

 

The biggest question to ask your builder is if he has experience porting LS heads, or just older stuff. Just because he can port a SBC head doesn't mean he won't just ruin a LS head.