If you’re like most drivers, your understanding of how a car engine works amounts to a vague sense that you put gas in, there’s some kind of a fire, and you advance forward.
For many, that’s all the information they want. But the curious need more, and so here you have it.
This is how a car engine works:
Think of your car’s engine as a big air pump, because that’s exactly what it is. The gasoline, the pistons, the spark plugs – they’re all in there to facilitate pumping air through the engine, thereby generating power. There are a lot of different types of air pumps, but in the case of the internal combustion engine, the energy to get the pump pumping is generated by mixing air with fuel and setting that concoction on fire.
It all starts with the air outside the car. That air is filtered by the air filter, then immediately mixed with fuel, either through a carburetor (in older vehicles) or a fuel injection system. That mixture of fuel and air is then sent through the intake manifold, which routs it to the cylinder head(s).
The cylinder head acts as sort of a gatekeeper between the intake and the combustion chambers (cylinders). Most cars have either four, six, or eight combustion chambers, and if all of those chambers ignited their air-fuel mixture at the same time the engine would not run smoothly or generate much power. For the pump to work smoothly and efficiently, delivery of the fuel mixture and the spark that causes the explosion have to be timed out just right.
In order for this to happen you need some valves, and you need those valves to open at just the right moment. In a car engine, these valves are part of the cylinder head, and they are opened and closed by the rotation of the camshaft, which spins inside the engine, using oblong lobes to push the valves open. With its intake valve open, a cylinder is filled with the fuel mixture. Now you need something to distribute the spark to the combustion chamber. Here enters the distributor. The camshaft and the distributor are buddies, connected by gears so that the distributor knows at all times which cylinder needs a spark.
When the intake valve opens, the distributor sends a spark through a spark plug wire to the spark plug. This makes a spark inside the cylinder, which in turn causes an explosion. That explosion forces the piston downward, pushing it against the crankshaft, resulting in the rotation of the crankshaft. This rotation, in turn, spins the transmission, which spins the driveshaft, which spins the wheels. At highway speed, the crankshaft will be spinning at a rate of about 3,000 revolutions per minute (RPM).
Simultaneously, exhaust valves let out the remnants of the burned fuel mixture, routing them through the exhaust system and filtering them along the way.
It’s just that simple. The more air you pump, the more power you make.