Originally Posted by Longshot270
The high octane is safer for your engine than the E10. Octane rating just refers to the stability of the fuel. Higher number means it is more stable.
The higher number means it burns slower. Gasoline actually burns too fast for hi-compression motors and is not resistant to pre-ignition. That's why if you put regular gas in a hi compression motor you get "ping". And the additives needed to slow down the burn cost more so the the price for hi-test premium is higher. Alcohol has a hi octane rateing which is why it's used for racing, it just takes twice as much alcohol as gas. Air/fuel ratio for gas is 14:1, for alcohol it's 7:1. A not-so-cheap way to raise octain rating is to add tolulene, a paint thinner, to the gas. Tolulene has an octane rating of 117 which is why it's added to gas now. When they first cut-off tetra ethyl lead for use in gasoline they needed something to raise the octane and tolulene is one of the things they used.