Easy-to-understand diagrams of an internal-combustion engine exist online at Driving-Test-Success.com and HowStuffWorks.com, as of 2015. The diagrams are cross-sectional drawings of the internal combustion process.
The diagram on HowStuffWorks displays and labels the parts of each single cylinder. The critical components it includes are the camshafts, valves, piston, crankshaft and engine housing. The diagram also turns into an animation of the process and marks each stroke duration. Engine anatomy differs based on the type of engine: if its cylinders are in-line, flat or V-shaped. The number of cylinders also affects the stroke timing of each piston.
The diagrams on Driving-Test-Success.com are simple 3-D views of more of the engine, including the belts, alternator and distributor. There is also a 3-D diagram of the transmission.