The make up of an automobile engine varies based on the expected performance. For example, a greater number of cylinders are required for more power and highly tuned parts made to withstand greater heat are required for heightened speed. An automobile engine made for a truck or SUV requires more power than an engine made for use in a small car or minivan.
Within an automobile engine, you will find cylinders. Within each cylinder is a piston. The piston cycles up and down opening and closing the intake valve. In small engines, there is often just one cylinder, while in larger equipment or vehicles, there can be many more. The range for a common automobile engine runs from four cylinder to eight cylinder, with six cylinders being a commonly used construction. When you hear someone say a car is a V6 or a “six banger” that means it is a six cylinder engine.
As the piston moves downward, fuel and air are combined and pulled into the combustion chamber via the intake valves. When the piston changes course, the valve closes. This leads to increased temperature and pressure of the fuel and air mixture. The piston rings create a seal between the piston and the cylinder, which helps keep the fuel and air mixture from leaking.
Then another part takes its turn. The spark plugs give off a spark, which in turn causes the air and fuel mixture to begin burning. The heat generated by this process causes the mixture to expand, which pushes the piston back down, generating power. Now, the piston must continue its cycle, working its way back up.
During the upward movement, the exhaust valve rather than the intake valve will now open, releasing air and fuel that has not been burned. This mixture will make its way through the engine, to the manifold, and will ultimately be expelled through the exhaust pipe. This process repeats as long as the automobile engine is running.
The cylinder, the piston, piston rings, the intake valve or valves, combustion chamber, spark plugs, exhaust valve, and the exhaust manifold are all basic components. The automobile engine, while innovative and useful, is based on simple parts and processes that work together, essentially to turn fuel into energy. What is described here is the way an automobile engine works with a common four-stroke cycle.