The octane rating of an engine is a standardized measurement of engine performance. The Research Octane Number comes from a standardized RON test and determines a fuel’s performance and the point at which it ignites instead of burning.
A higher octane number means fuel can withstand greater compression before reaching its ignition point. Fuels with higher octane ratings are ideal for high performance gasoline engines such as those in sports cars and modified or imported vehicles. When an engine begins making a loud knocking sound, this can indicate irregular fuel combustion.
The octane levels of any fuel or octane booster are testable in a laboratory setting to record its octane number. Technicians perform the RON test with an engine running at a low speed of 600 rpm. The test utilizes a specialized engine with a low compression ratio.
The first test runs the engine with an iso-octane and N-heptane fuel mixture to provide a reference. Then the test runs the engine with the specified fuel. The compression rises until the engine stops smoothly burning fuel and instead detonates the fuel before it can reach the spark plug.
The resulting numbers of the ratio of the two cylinder pressures provide the RON of the fuel tested.