This diagram shows the flow of fuel and exhaust within a V8 engine.
Fuel enters the cylinders via the intake manifold.
The spark-caused explosions force the pistons down. Rotation of the crank forces the pistons back up, which expels the exhaust. This animation shows the route taken by the oil within an engine. The oil pump draws oil from the oil pan, then forces it through the filter, into the crankshaft passage, through the connecting rods to the pistons and rings. Oil is pushed through the lifters and pushrods, and covers the rocker arms.