Nearly all vehicles on the road today use an internal combustion engine that burns gasoline or diesel fuel. Regardless of the type of fuel that is burned, nearly all engines operate in a similar fashion and share common terms when describing their specifications.
How does an engine work?
In the most basic definition, an internal combustion engine is nothing more than an air pump. Air is drawn in on one end, mixed with fuel and ignited (internal combustion), and forced out the exhaust. The engine converts the energy from combustion into the mechanical power to drive the vehicle.
Common engine terms
To simplify things, vehicle manufacturers use common mechanical terms to describe the size and power of the engines in their vehicles. The descriptions often tell quite a bit about the engine itself (for example, 1.8 liters, inline-4, 20 valves, and turbocharged). Decoding this designation is simple if you know what to look for, and what each term means:
Engine size/displacement
The displacement of an engine, or its size, is the volume of air the engine can move during one engine cycle. It is commonly expressed in liters or cubic inches, depending on the manufacturer (a 5.7-liter engine equals 350 cubic inches). In general, larger engines will deliver more power, and use more fuel.
Cylinders
The word "cylinder" refers to the cylindrical shape of the chambers where air and fuel are mixed and burned inside an internal combustion engine. Each chamber is counted as one cylinder. In general, the greater the number of cylinders an engine has, the greater the power and fuel consumption. To conserve fuel, some modern 8-cylinder engines have been designed to shut down cylinders when they are not needed (highway cruising, for example).
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