B5BITURBO

A friend told me he used to run his GIAC chip in race mode all the time on 93 and it was fine, just a manufacturer's suggestion for 100 to cover their ***. How safe do you guys think this is?

Leester

I think thats a horrible idea. 93 octane doesnt burn slow enough for that kind of timing advance.

DAP@EPL

Agreed

B5BITURBO

Thanks, kinda what I figured just wanted to get a general consensus on this.

B5QShip

Not only is it not safe, but your car might even run slower in 100 oct mode on pump gas because it may move to a less agressive timing map to keep from throwing a rod through the block.

Flyboy

it's is less susceptible to detonation. You can compress it more, generating more heat, before the temps in the cylinder and compression process cause it to ignite at the wrong time.

blrx7r1

How much below 100 octane is 'safe'? The highest pump we have is 92. So chances are I'll have some 92 still in there with the 100.

Leester

Well, higher octane is less volatile and hence burns slower I thought.

Flyboy

a rating of the resistance of gasoline to auto-ignition. Basically it is more resistant to breaking down into the components that are susceptible to igniting as a result of temperature and pressure in the cylinder. It doesn't have anything to do with the burn rate. There are things that affect burn rate, octane isn't one of them. I believe that as you look at gasses with higher octane ratings you find that burn rates typically increase, but not because of the increasing octane level.

Flyboy

I think that's going to depend on how you drive. I wouldn't try it if it were my car.