| General Information

The gasoline-powered internal combustion engine is the most popular engine in the world, powering millions of cars. Chances are you use a car on a daily basis – have you ever turned your ignition over and wondered what’s going on under the hood? Our fleet fuel card company explains:

The name “internal combustion” comes from the process of turning gasoline into motion by creating tiny, frequent explosions. Engines use a four-stroke combustion cycle that includes intake, compression, combustion, and exhaust. This cycle repeats over and over again and the engine harnesses the energy in order to move the car forward.

The Process

During intake, a cylinder’s intake valve opens and the piston inside moves downward to bring air and gas into the chamber. Once the piston moves back up again, it begins the compression cycle where the air and gas is pressed into a smaller space. In this small space, the spark plug ignites and creates an explosion that forces the piston back down (also known as combustion), and as the piston travels back down, an exhaust valve opens to release the waste gas created by the explosion. The waste gas moves through the car’s catalytic converter and is cleaned before it passes through the muffler, then is exhausted out of the tailpipe.

This process happens over and over again to create the energy the car needs to move, and the harder you press the gas pedal, the more the throttle valve opens up. A larger valve opening means more air that goes into the engine and the faster the process happens.

Power Factors

Most car engines have four cylinders, but by increasing the number, you can increase the gas displacement. Some cars have six, eight, ten, or even twelve cylinders (otherwise known as a “v6,” “v8,” “v10,” or “v12” engine, respectively).

Engines can also be tuned to be more powerful by adding a turbocharger or a supercharger. Both of these force more air into the engine to create more power, however, the way they do it differs. A turbocharger uses a turbine that gets its energy from the exhaust stream while a supercharger gets its power from a belt connected directly to the engine.

Diesel Engines

Because diesel engines run on a different kind of fuel, they produce a different kind of energy. Diesel fuel burns evenly, as opposed to gasoline, which burns all at once (during the combustion part). This means that all of a diesel engine’s energy is released steadily, letting it produce more from a given amount of fuel. Because it’s released steadily, a diesel engine’s exhaust will also be cooler than gasoline engine’s. In addition, a diesel engine has no throttle valves, which means the amount of air pumped into the engine stays steady.