What is an Octane Number?

The octane number that is given to gasoline fuel is a measure of its anti-knocking qualities.

Australia is blessed in having many types of gasoline fuels to quench the thirst of its large motor vehicle fleet. Unleaded Petrol is the most common fuel type in Australia for passenger vehicles. Unleaded petrol, or ULP for short, has a Research Octane Number (RON) of between 91 and 93. The octane number is a measure of a fuel’s compression performance. The Research Octane Number that is given translates into the amount of engine power. RON requirements vary according to engine type.

It is important that the right octane fuel be used for a particular engine. Each engine has been specifically designed to run on a particular fuel octane type. A knocking noise can occur in an engine when there is a mismatch between the fuel characteristics and the engine’s design, particularly its compression ratio, resulting in the pre-igniting of the fuel mix in the combustion chamber. This pre-ignition is also known as ‘pinging’.

So the next time that you pull up to the service station to fill your car up with petrol, be sure that your selection of fuel is such that you are correctly matching the octane number to you motor vehicle’s engine requirements. This will ensure that the knocking fuel-effect caused when the fuel combusts in the compression chamber too early will not occur.

Many imported cars, and particularly those with turbochargers, are manufactured to run on premium unleaded petrol. 98 RON is a high-octane unleaded fuel that maximizes engine power and performance, as well as producing less pollution. 98 RON is promoted as providing excellent fuel economy, has a sulphur content which is 10 times lower than the national standard for unleaded fuels, and has low levels of benzene, sulphur and lower aromatics. 98 RON is used by some imported and high performance vehicles We hope that helps answer the question ‘What is What is an Octane Number?’!

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