So I'm interested in doing FI build and was wondering if there are any negatives in running 317s for maybe 6 months or a year with a small cam on my car besides loss of power? Basically would it hurt my car to lower the compression that much for that long?

 

It really wouldnt hurt you at all to do that. Like you said, you would just be down in power.

 

Generally a decent combo will get effected approximately 20hp per point between 8.0:1-14.0:1. Running those wont hurt you. You may even be able to make similar power on lower octane fuel if you can tune to take advantage.

 

Appreciate the clarification. Thanks.

 

With common compression ratios (8-13 or so) Everything I've read says a point of compression is worth roughly 4% of the total HP. This figure has diminishing returns as you go higher in the compression range and increasing returns vise versa.

If he were to lose 20HP he'd have to be making 500hp.

So taking a 310hp stock ls1 and dropping it to 9:1(ish) would lose approx. 12.4hp. And thats at the flywheel.