I've gotten different answers With my 12:1 piston should I run 110 or will I be alrite with 94?

 

I run VP C12 which is really 108 Motor octane on my 12:1 460EX. Personally, I think you should run at least 105, but give yourself some allowances if you are lower in elevation. If you run at sea level dont skimp on octane. I always run slightly MORE octane that recommended because I like to have a small buffer. When I say slightly more, I am saying no more than 2 or 3 more octane that recommended by the piston manufacturer.

 

Easiest thing to do is try it. Start with the 94 and drive around a little. Try going up hill at low rpm's. When the engine starts lugging down listen for a knock. When my octane level was too low this is how i found out. I would always hear a metal to metal knocking sound.

 

That metal to metal sound you heard was your valves chattering , trucks and cars will do it also .....

 

the metal to metal knock of running to low of octane is called spark knock. spark knock is when the fuel doesn't burn completely through out the combustion chamber leaving unburned fuel to have a kind of diesel effect. so istead of the spark causing a complete burn like it should the compression is making the fuel detonate. it has more of a pinging sound to it when the engine is under a load like climbing a hill a low rpms or heavy acceleration.

 

Ya, that describes it a little better muddstudd. It is a pinging sound. I also noticed it is much more pronounced after I removed my airbox lid. Anyhow, I run Super (91) and it took care of it.

 

WheelieKing, id try running premium in it and see if you have spark knock. i've a read several places that untill you get to about 13:1 compression you should be ok. if anything you could just buy an octain booster from a gas station or an auto parts store and mix it as it says on the bottle. i don't know where you live but here in missouri about five years ago 110 octain was about 4.50 a gallon and we had to drive 45 minutes to get it. i can't imagine how much it would cost now.


edited for spelling