The octane rating of a fuel is determined by comparing it with which substances?

The octane rating of a fuel is established by comparing its combustion characteristics to those of two reference substances: heptane and iso-octane. Heptane has an octane rating of 0, which indicates very poor resistance to knocking, while iso-octane has an octane rating of 100, representing high resistance to engine knock.

This comparison is crucial in assessing how well a fuel will perform in an internal combustion engine under various conditions. A higher octane rating signifies that the fuel can withstand greater pressure and temperature before igniting, allowing for more efficient engine performance and less knocking. This makes the choice of heptane and iso-octane the standard method for determining the octane rating of fuels, establishing it as critical knowledge in the field of engine technology and fuel chemistry.