The combustion chamber in an engine is where the magic happens. It’s where fuel, air, pressure, and electricity come together to create the small explosion that moves the car’s pistons up and down, thus creating the power to move the vehicle. The combustion chamber is made up of the cylinder, piston, and cylinder head. The cylinder acts as the wall of the combustion chamber, the top of the piston acts as the floor of the combustion chamber, and the cylinder head serves as the ceiling of the combustion chamber.
The cylinder head is a piece of metal that sits over the engine’s cylinders. There are small, rounded indentations cast into the cylinder head in order to create room at the top of the chamber for combustion. A head gasket seals the joint between the cylinder head and cylinder block. Intake and outtake valves, spark plugs, and fuel injectors (these parts are explained later) are also mounted to the cylinder head.
Pistons move up and down the cylinder. They look like upside down soup cans. When fuel ignites in the combustion chamber, the force pushes the piston downward, which in turn moves the crankshaft (see below). The piston attaches to the crankshaft via a connecting rod, aka the con rod. It connects to the connecting rod via a piston pin, and the connecting rod connects to the crankshaft via a connecting rod bearing.
On the top of the piston, you’ll find three or four grooves cast into the metal. Inside the grooves piston rings are put in. The piston rings are the part that actually touch the walls of the cylinder. They are made from iron and come in two varieties: compression rings and oil rings. The compression rings are the top rings and they press outward on the walls of the cylinder to provide a strong seal for the combustion chamber. The oil ring is the bottom ring on a piston and it prevents oil from the crankcase from seeping into the combustion chamber. It also wipes excess oil down the cylinder walls and back into the crankcase.
The crankshaft is what converts the up and down motion of the pistons into a rotational motion that allows the car to move. The crankshaft typically fits lengthwise in the engine block near the bottom. It extends from one end of the engine block to the other. At the front of the end of the engine, the crankshaft connects to rubber belts which connect to the camshaft and delivers power to other parts of the car; at the back end of the engine, the camshaft connects to the drive train, which transfers power to the wheels. At each end of the crankshaft, you’ll find oil seals, or “O-rings,” which prevent oil from leaking out of the engine.
The crankshaft resides in what’s called the crankcase on an engine. The crankcase is located beneath the cylinder block. The crankcase protects the crankshaft and connecting rods from outside objects. The area at the bottom of a crankcase is called the oil pan and that’s where your engine’s oil is stored. Inside the oil pan, you’ll find an oil pump that pumps oil through a filter, and then that oil is squirted on to the crankshaft, connecting rod bearings, and cylinder walls to provide lubrication to the movement of the piston stroke. The oil eventually drips back down into the oil pan, only to begin the process again
Along the crankshaft you’ll find balancing lobes that act as counterweights to balance the crankshaft and prevent engine damage from the wobbling that occurs when the crankshaft spins.
Also along the crankshaft you’ll find the main bearings. The main bearings provide a smooth surface between the crankshaft and engine block for the crankshaft to spin.