How Does a Gas Motor Work?

Fuel

Gas motors are motors that utilize gasoline as a fuel source, as opposed to electricity or any other alternative fuels. Gasoline is volatile, especially its fumes, in certain situations that involve ignition and oxygen. A gas motor creates that situation, known as combustion.

The Combustion Chamber

In general, gas motors are designed to allow fuel and oxygen to mix together in a special combustion chamber. Ignition is added via a spark plug that releases a hot, electrical arc into the chamber. The spark plug typically fires at least 20,000 volts into the chamber.

A piston attached to a crankshaft is responsible for compressing the air and fuel mix to be more volatile. As the piston's stroke goes up, it pushes the air-fuel mix towards the spark plug, which then fires its arc. The result is heat energy.

Exhaust

That heat energy cannot stay in the combustion chamber for very long. The gas motor's piston releases it when the piston goes through its down-stroke. The down-stroke opens up an exhaust pipe for the energy to travel through, powering the vehicle.

Two-Stroke vs. Four-Stroke

Gas motors come in different sizes, depending on their intended use. Most motors for push mowers and other lawn appliances use two-stroke gas motors. Two-stroke motor spark plugs fire during every revolution. Larger motors that power vehicles utilize a four-stroke gas motor system, where spark plugs fire during every other piston revolution. Two-stroke motors also have less fuel efficiency since they fire more often.

Starting and Cooling System

Gas motors used in cars often require a starting system. Most car engines are too large and complicated to start on their own. The starter system rotates the engine's combustion system just enough to begin the cycle. That requires enough energy to overcome the friction generated from the pistons at a still position and the compression of pistons that are still in the "up" stroke.
Larger gas motors also must incorporate a cooling system, since they generate more heat that if left unchecked could damage the engine. Motorcycle engines are often air cooled since they are already exposed to the elements. Car engines utilize water and a radiator that cycles special coolant throughout the engine.