For example, the catalytic converter uses a catalyst and oxygen to burn off any unused fuel and certain other chemicals in the exhaust. The emission control system in modern cars consists of a catalytic converter, a collection of sensors and actuators, and a computer to monitor and adjust everything. Without a muffler, what you would hear is the sound of thousands of small explosions coming out your tailpipe. The exhaust system includes the exhaust pipe and the muffler. Now that you know about some of the stuff that you put in your car, let's look at some of the stuff that comes out of it. The oil then trickles down into the sump, where it is collected again and the cycle repeats. In most cars, oil is sucked out of the oil pan by the oil pump, run through the oil filter to remove any grit, and then squirted under high pressure onto bearings and the cylinder walls. The two main parts needing oil are the pistons (so they can slide easily in their cylinders) and any bearings that allow things like the crankshaft and camshafts to rotate freely. The lubrication system makes sure that every moving part in the engine gets oil so that it can move easily. A supercharger is attached directly to the engine to spin the compressor. A turbocharger uses a small turbine attached to the exhaust pipe to spin a compressing turbine in the incoming air stream. The amount of pressurization is called boost. High-performance and modern fuel-efficient engines are either turbocharged or supercharged, which means that air coming into the engine is first pressurized (so that more air/fuel mixture can be squeezed into each cylinder) to increase performance. But why is air circulation so important? Most cars are normally aspirated, which means that air flows through an air filter and directly into the cylinders. So now you know how and why your engine stays cool. Air-cooling makes the engine lighter but hotter, generally decreasing engine life and overall performance. In a few cars (most notably pre-1999 Volkswagen Beetles), as well as most motorcycles and lawn mowers, the engine is air-cooled instead (You can tell an air-cooled engine by the fins adorning the outside of each cylinder to help dissipate heat.). Water circulates through passages around the cylinders and then travels through the radiator to cool it off. The cooling system in most cars consists of the radiator and water pump. Next, we'll learn what can go wrong with engines. It contains some amount of oil, which collects in the bottom of the sump (the oil pan). The crankshaft turns the piston's up-and-down motion into circular motion just like a crank on a jack-in-the-box does. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates. The connecting rod connects the piston to the crankshaft.
That's one of the reasons why engines last longer and can go longer between oil changes. Many modern vehicles use more advance materials for piston rings. Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly. They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion.Now let's look at all the parts that work together to make this happen, starting with the cylinders. The rotational motion is nice because we plan to turn (rotate) the car's wheels with it anyway. In an engine, the linear motion of the pistons is converted into rotational motion by the crankshaft. Now the engine is ready for the next cycle, so it intakes another charge of air and gas. Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe.The gasoline charge in the cylinder explodes, driving the piston down. When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline.Compression makes the explosion more powerful. Then the piston moves back up to compress this fuel/air mixture.
Only the tiniest drop of gasoline needs to be mixed into the air for this to work.