A rating of the 'knock' characteristics of motor fuels. The octane number is equal to the numerical value of the percentage by volume of iso-octane, C8H18, in a mixture of iso-octane and heptane, C7H16, having the same knock characteristics as the fuel being tested.
The higher the octane number or rating, the greater are the antiknock qualities of the petrol. A rating of how much fuel can be compressed before it ignites spontaneously.
|Diesel Fuel||15 to 25|
Methyl Tertiary Butyl Ether
A fuel oxygenate used as an additive to gasoline to increase octane and reduce engine knock.
One gram of Tetraethyl Lead increases the octane of one gallon of gasoline about 6 numbers. The EPA has phased down the use of lead in gasoline as it has been determined to be a health hazard. Lead has been prohibited in highway vehicle gasoline since January 1, 1996.
Derived from petroleum and used to increase octane. Xylene is highly photochemically reactive and, as a constituent of tailpipe emissions, is a contributor to smog formation.