What is the maximum compression ratio to run on 93 octane?

Answer 1

12.4:1. this is your final or corrected compresssion ratio(FC). By that I mean adding in corrected altitude

FC- (altitude/1000)x.02

your cam selection (see Keith black pistons calculators for dynamic and static compression)

and if you are running a supercharger

(boost / 14.7+1) x compression ratio= FC

Piston companies list there compression ratios for a factory combination. Factory deck height, rod lengths, and head gasket thickness because they don't know what you are running. This calculator takes into account the things you can change and the closing event of your intake valve to give a true compression rating or dynamic.

I learned this from Blower Drive service Tech info on there web site.

Also I have a supercharged 2003 harley Davidson editon F-150. Stock static compression is 8.5:1. I am running 12 pounds of boost and I have run as high as 16lbs, on 91 octane.

That would put my static compression ratio over 15:1 on 91 octane.

(12lbs / 14.7 +1)=1.81x8.5(static compression)=15.44

(16lbs / 14.7 + 1)= 2.08 x 8.5=17.75

YES I did tune the computer for my changes, and it does remap the fuel and ignition, and aluminum heads help too.

If you do all the math and build it to the edge for where you live, don't go cruz the California beach from Denver because the altitude will change the air density and your compression ratio.