i'm about to go 13-1 on the piston and i hear to run 110 octane. the guys at the snowmoblie shop say the higher the octane the slower the burn, they told me to pour a little on the ground of each and throw a match on and i would see the difference. since a 11.5 will run on 92, my question is why such a big jump for the 13-1 would 100 work or is it just trail and error method?

 

I run 100 octane unleaded with 12.5 piston, runs great.

 

i would look on VPracing website and see what your compression calls for, i run straight c-14 for motors 13:1 or over, and yes it is true if you have too high of octane it sometimes works against you... the burn rate is what you want to get dialed in..i would try different types of fuel in a drag race running the same opponent and see what gives you the best results without knocking... usually too high of octane will make it rich on top, losing power if not burning right. every motor combo likes to run different with different fuel, also depending on outside air temp, and air density..