Cylinder number and arrangement depends on the purpose of the engine. Smaller (four and six cylinder) engines in front-wheel drive vehicles often use an inline design which orients cylinders vertically over the crankshaft and aligns them in a row. Other common orientations are a horizontal/opposed design which places cylinders flat facing each other with the crankshaft between them and a V-type design common in six and eight cylinder engines that features one cylinder head per block of cylinders oriented at a 60 to 90 degree angle to each other with the crankshaft at the bottom of the V.

During the exhaust stroke, just before the piston reaches bottom dead center the exhaust valve opens. The resulting gases from combustion are then pushed out through the exhaust valve as the piston travels up the cylinder to top dead center, completing stroke four of the four-stroke piston cycle.

The fuel injector sprays fuel into the air stream that's being fed into the cylinder head via the intake valve. The timing and amount of fuel are regulated by the powertrain control module (PCM) which is the main computer that controls engine and transmission functions.

The wheel hub is the mounting point for the wheel and tire assembly. The wheel hub can rotate while being held stable by the steering knuckle which applies the motion of the control arms to the wheels.