What does the octane rating of gasoline mean?
(Lansing State Journal, October 16, 1996)

To understand octane rating, you need to understand a little bit about how car engines work.

The engine’s power comes from carefully controlled explosions of gasoline/air mixture inside the engine.  To control the explosions, the gasoline must burn at exactly the right rate.  This is controlled by the gasoline’s chemical composition.

Gasoline is a mixture of many chemicals that burn at different rates.  One chemical that burns at the right rate is isooctane.  A chemical that burns too quickly is n-heptane.  To describe how fast a gasoline burns, a scale was developed using these two chemicals.  Isooctane is defines to have an octane rating of 100, which n-hepatine has an octane rating of 0.  Octane ratings compare the burning characteristics of gasoline to mixtures of isooctane and n-hepatane.

For example, if a cheap gasoline burned the same way as a 50:50 mixture of isooctane:n-heptane, the octane rating would be 50.  Gasoline with an octane rating of 87 burns he same way that a mixture of 87 percent isooctane and 13 percent n-heptane would burn.

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