PerryB

Two things cause detonation. Too much timing advance and/or not enough fuel. Get it fixed right away or return it to stock tune. Continued detonation will either break the rings or put a hole in a piston. Its also hard on the crankshaft and rods.

techrep

iTrader: (1)

never saw 86... thought federal minimun was 87

redraiderford

I've only ever seen 86 in Lubbock and Amarillo. In Dallas 87 is normal

nrivera04

Some of the mountain states sell 85 as the minimum. The higher altitude lets the engines run better on lower octanes.