About Fuel

An internal combustion engine obtains its energy from burning fuel. The heat and pressure produced during the combustion of fuel keeps the pistons and crankshaft in constant motion. The fuel used may come in different forms, some more efficient than others, but all with the same purpose: to keep the car moving.

Function

Automobiles with internal combustion engines combine gasoline and air in predetermined amounts, depending on driving conditions, to create the perfect combustion. The combustion process produces the heat, explosion, gas expansion and pressure necessary to keep the pistons moving and the crankshaft rotating inside the engine.

Types

Gasoline and diesel fuels are just two of the most common fuels available to internal combustion engines. Some other alternative fuels include gasohol (a combination of alcohol and gasoline suitable for high-compression engines), liquefied petroleum gas (LPG, a lighter fuel than gasoline, requiring engine modifications for use in automobiles), ethanol and methyl (two expensive alcohol-based fuels which also require engine modifications, making them less attractive) and synthetic fuels, which seem to be gaining in popularity as crude oil prices keep increasing.

Origin

Gasoline, diesel and LPG fuels come from crude oil deposits deep underground. Oil companies extract the crude oil and take it to refineries where sulfur, nitrogen, metals and saltwater are removed. Ethanol is made from grain, wheat, potatoes and other farm crops. Methyl alcohol comes from wood chips, petroleum, garbage and animal manure, while synthetic fuel is made from coal, shale oil and tar sand.

Features

Refineries add special additives to gasoline fuel for proper combustion in automotive engines. This fuel performance characteristic is measured in octane ratings and designed for low- and high-compression engines. A low-octane gasoline fuel rated at 87, for example, is considered regular gasoline and suitable for most passenger cars which come equipped with low-compression ratio engines; 93 Octane, or premium fuel, is aimed for turbocharged and other high-compression ratio engines.

Considerations

Never use diesel in a gasoline engine. Compared to gasoline, diesel fuel delivers more energy per gallon and provides more pressure to the cylinders, but diesel is a thicker fuel than gasoline and doesn't vaporize as easily as gasoline does. Using diesel in an engine designed for gasoline fuel will render the engine useless. Gasoline engines can provide a vaporized air-fuel mixture to the combustion chamber, but won't be able to vaporize the thick diesel fuel, which will stick to the walls of the intake manifold.