What does an octane rating indicate?

An octane rating indicates a fuel's resistance to knocking, which is a critical aspect of engine performance. Knocking, also known as engine knock or detonation, occurs when the air-fuel mixture in the engine's cylinder ignites prematurely, leading to a decrease in performance and potential engine damage.

A higher octane rating signifies that the fuel can withstand higher compression ratios before igniting, thereby allowing for more efficient combustion in high-performance engines. This resistance helps prevent premature ignition during the compression stroke, ensuring smoother engine operation and maximizing power output while minimizing the risk of damage. Therefore, octane rating is essential in determining the suitability of gasoline for various engine types and their configurations.

While other factors such as fuel density, energy content, and combustion temperature are important characteristics of fuels, they do not specifically relate to the octane rating and its primary role in preventing knocking.