What is knocking in gasoline?

Gasolines with the same trade name and the same octane rating may differ slightly in severe sports driving.

Gasolines are mixtures of carbon and hydrogen compounds containing from 5 to 12 carbon atoms per molecule. Crude gasoline, obtained directly from the refining of crude oil, is refined to produce a variety of fuels for commercial distribution.

One of the most important indicators characterizing the behavior of gasoline during combustion in the engine is the octane number. It shows how resistant the fuel is to detonation combustion. Some of them contain more light hydrocarbon fractions. These cuts have a lower octane rating and cause detonation combustion when the gas is added quickly.