What is a Piston Engine?

The piston engine is the most common type of power-plant found in today's automobiles, boats and practically all other self-powered machinery in the world. Whether it be gasoline-, alcohol- or diesel-powered, the piston engine is being used to power most of mankind's most prized mechanical possessions. The piston engine uses pistons connected to a crankshaft by connecting rods to send power to a transmission. The engine receives a fuel and air mixture through a carburetor or a fuel injection system. It sends the fuel mixture into the combustion chamber through the intake manifold and through the heads. The mixture is ignited by the spark plugs and drives the piston downward, and this causes the crankshaft to spin and produces power.

The enemy of any piston engine is heat. Some engines are cooled by air while the most common way of cooling an engine is with liquid coolant. This is pumped through the engine block and heads by the water pump. The heated coolant is pushed out of the engine and into the radiator. There, it passes through tiny rows of small passages and the heat is pulled out of the liquid by rows of thin aluminum.

The cool air is pulled through the radiator by a cooling fan. The cooled liquid is once again pushed into the heated engine by the water pump where the entire process begins again. The coolant's temperature is controlled by a thermostat placed in the return radiator hose where it determines the speed at which the coolant leaves the radiator.

The piston engine is essentially nothing more than an air pump. An engine's ability to make horsepower is determined by its ability to pump air. The ability to pump air out is directly affected by its ability to draw air in. The carburetor and exhaust are two of the most critical components when attempting to make more horsepower and a more powerful engine.

Any piston engine is limited by its ability to breathe. The camshaft is the brain of the piston engine. It dictates the length of time a valve is open. It also determines how fast a valve opens or closes.

Valve timing in a piston engine is critical. The valves must open and close precisely in order for the engine to be able to make power. Fuel mixture is also tantamount to performance. Too much fuel can result in poor performance and fouled spark plugs. Too little fuel and the engine will begin to destroy itself by burning pistons and valves.