What Is an Octane Number? Definition, Meaning and Concept

An octane number is a number that reflects a fuel's resistance to shock. Knocking occurs when fuel burns prematurely or explodes in an engine, causing a distinctive noise that resembles knocking, rattling or knocking. Engine knock can damage the engine and indicates that the engine is not running as efficiently as it could be. Many engines come with specific octane rating recommendations.

Octane values ​​are obtained by testing a fuel under controlled circumstances. Two different types of octane measurements can be obtained: Research Octane Number (RON) or Engine Octane Number (MON). These numbers are obtained by testing the fuels under different circumstances, with the MON putting more stress on the engine to see how the fuels perform under difficult circumstances. Octane ratings on a gas pump often reflect an average value.

These numbers are calibrated against a scale. Two chemicals, heptane and isooctane, are used to create benchmarks on the scale, with heptane at zero and isooctane at 100. When a fuel is tested in an engine, it is compared to a mixture of heptane and iso - octane rating to see which combination most closely matches fuel economy. If the mix includes 20% heptane and 80% isooctane, for example, the fuel will have an octane value of 80. Octane numbers can be adjusted by adding additives to the fuel that will adjust the knock level.

It is possible to have an octane number beyond 100, since isooctane is just one point on the scale. High performance fuels often have very high octane values; rocket fuels, for example, have octane values ​​greater than 100. The higher the octane value, the more pressure the fuel needs to burn. This is desirable as the goal is to avoid actual explosions and instead create a controlled ignition of the fuel. If a low octane fuel is put into an engine designed for high octane gas, the fuel will cause explosions, damaging the engine, because the engine puts a lot of pressure on the fuel by design.

Drivers are often concerned with the octane number because they need to select the best fuel for their vehicles. As a general rule, it is best to follow the vehicle manufacturer's recommendations. Putting high octane fuel in a car designed for lower octane fuel is not very productive. In contrast, some cars designed to run on premium fuel may run regularly, because the octane rating differs by typically a few percent, although drivers should be aware that this can cause engine damage, and the practice generally does not. it is recommended.