Definition - What does Octane Rating mean?
Octane Rating is referred to as the standard measure of the performance of aviation or engine fuel. A Fuel with a high Octane Rating can withstand more compression before igniting. The fuels with high ratings can be used in the high performance engines of gasoline which require high ratios of compression. Fuels with low ratings are considered ideal for the diesel engines whereby instead of compressing the fuel they compress air and inject the fuel into the air that is heated up due to the compression.
Petropedia explains Octane Rating
Octane Rating is considered as the measure of the ability of fuels to resist the knock. The ratings of gasoline are measured in a test engine defined by the comparison with the blend of heptane and trimethylpentane which have similar anti-knocking ability as the fuel under test. The rating does not indicate the content of the energy in the fuels. They are considered as the tendency of fuel to burn in a limited manner instead of exploding uncontrollably. When the Octane Rating is raised by mixing ethanol, the energy content reduces per volume.