LQ9's have a CR of 10.0:1 and make 345 HP
L76's have a CR of 9.6:1 and make 355 HP

I'm guessing its because the L92 Heads on the motor and the cam are SUPERIOR to the LQ9's? Because if they were running the same compression and fuel then the L76 would have about 50 more HP than the LQ9. I want to know what the difference is and can the LQ9 use the L76 heads if that's the only difference? Or is the difference in the tune? or both?

What would a LQ9 with a mild cam and L76 heads do and would it still be able to run less 87 Octane?

400 HP on 87 would be sweet... But Even if thats not attainable, what could be done while keeping the CR the same on the L76 and attain more power?

 

First off:

You don't build performance cars based around 87 octane. If that's truly your goal, then find another hobby

You can use the Gen IV rectangle-port heads on any block with a 4.00"+ bore.... LS2, LQ4/9, L92, LS3, LS7, etc.....

L92 heads are what you're looking for......

 

Higher octane fuel just burns slower, it's not much different then pulling timing. You could run a higher compression motor on 87 octane, but would have to pull timing to do it. But that starts to decrease higher RPM hp...

 

good answer!