Explain the octane rating system used in gasoline, and the prupose of additives in fuel. (see below for more.)

Question

This also has to be in a well developed paragraph but not a dissertation.

Answer 1

The octane number just means the percent octane that the gas is. A higher octane number burns better, but is more expensive. The normal (cheapest) gas is 87 octane, which means it is 87% octane and 13% heptane.
Fuel addatives either increase fuel economy or the life of the engine. They help the fuel burn better

Answer 2

Octane Rating System

Answer 3

The octane rating comes from burning the fuel in a small test engine. The higher the octane number, the less "knocking" there is in the running. Knocking is caused by an unevenly distributed explosion of the fuel-air mix in the cylinder. In a car, it sounds like someone left a load of nuts and bolts under the wheel covers (LOL). Knocking hurts the performance of a high-compression engine.

The "octane" reference used in the test is actually pure 2,2,4-trimethylpentane, which is also called "isooctane" in the industry. Octane is rated at 100, and heptane is rated 0 (miserable knocking). The tester rates the fuel as if it were an octane-heptane mixture.

Things that increase the octane rating (make the fuel "more like octane") are aromatics, methyl tert-butyl ether (MTBE), tetraethyllead ("lead"), and methylcyclopentadienylmanganese carbonyl. Aromatics like benzene, toluene, and the three xylenes are increased in gasoline by platinum-catalyzed reforming ("platforming") at the refinery. All these agents produce smoother, more uniform explosions in the cylinder.