Flexi Says: Octane ratings for gasoline are a measure of the ratio of two different hydrocarbon compounds in the gasoline: iso-octane (an isomer of octane) and heptane. The higher the octane rating, the greater the ratio of iso-octane to heptane. Higher octane fuels can be compressed more before they ignite. In standard gasoline engines, this reduces "knocking" and increases performance.
