The octane number is a measure of the antiknock performance of a gasoline or gasoline component, the higher the octane number, the greater the fuel's ability to resist engine knock. There are two types of octane number, the Research Octane Number (RON) and the Motor Octane Number (MON), which are based on different engine operating conditions.
Knocking is the explosive or uncontrolled combustion of fuel in an engine's combustion chamber that can very quickly destroy an engine. The higher the fuel's octane number, the more resistant it will be to knock. Higher-octane fuels allow engine manufacturers to design more powerful and fuel-efficient engines.
"Knock" is an uncontrolled and explosive ignition of a hydrocarbon fuel, such as gasoline, in the combustion chamber. It causes a knocking or pinging sound, robs the engine of power and, left unchecked, causes serious engine damage. Fuel's tendency to knock is measured by its octane number. Lower numbers denote greater knock
Higher octane levels simply allow for more compression before knocking occurs. Which Octane Grade is Right for My Vehicle? Reading your manual is the key to knowing which level of octane you need for your vehicle or equipment. The majority of cars just need regular octane, but higher-performance cars tend to require a higher octane level.
Octane Number. Octane number of a fuel is the measure of its antiknock quality when its used in a spark ignition, internal combustion engine, as compared to the antiknock quality of Iso-octane (2,2,4-trimethylpentane). The octane number of a fuel is measured in a test engine against a mixture of iso-octane and heptane.
Engine knocking is in fact a pulse detonation and we all known what that can do an engine. Thus, the likelihood to engine knocking is reduced and the engine runs more smoothly. Directionally as the compression ratio of the engine increases so does the required octane number of the gasoline if engine knocking is to be avoided.
In addition to this the Octane number of some components used in gasoline blending, such as reformate, should also be monitored. The conventional method of Octane number measurement is called the knock engine method. In this method the fuel is combusted and its combustion is compared to that of known standards.
Knocking in diesel engine is due to delay in combustion of diesel oil by compression. The % of iso-octane in a mixture of iso-octane and n-heptane, which matches the fuel under test in knocking characteristics, is called octane number of petrol. Higher the cetane number of fuel less will be its knocking in petrol engine and better its quality.
1.4.2 Measured differences in knock intensity are scaled to provide a positive or negative delta octane number of the stream sample from the comparison reference fuel when the fuels are compared at the same compression ratio.