Quote Originally Posted by rspears View Post
Dave,
I like Robot's approach, try a few gallons of the 87 octane and see if it pings at full throttle through your load range, and especially at your cruise rpm when you'll be pushing it on grades, passing, etc. If you get minor pinging then try backing off the timing a couple of notches as you said. Increased octane slows the burn rate in the cylinder, so you actually get the highest efficiency running the lowest octane that your engine can stand. The old adage that premium gave more power was simply not true on a given engine and no change in timing.
Roger - great idea - except I have about as much chance of hearing a ping as you do with yours The engine exhaust "music" is kinda overwhelming to my 50% hearing loss ears along with that wind rustling all 157 hairs still on my head. I'll knock the timing back a degree or two.

Yeah, I do know about the slower burn/combustion rate. I think the last car that needed 'premium' was my '86 Mustang GT - 87 made that one sound like a death rattle.