A modern common automotive engine is essentially composed of :
- The crank gear i.e. the moving element including the crankshaft, connecting rods, pistons and the flywheel (not shown).
- A one piece light alloy or cast iron cylinder block, including a certain number of cylinders in which the pistons are sliding, crankshaft main bearing webs, coolant chambers and oil ducts. The crankcase is nowadays an integral part of the cylinder block.
- The cylinder head which closes the top of the cylinder block and form the roof of the combustion chambers. The valve gear, term including the valves and their actuation system, is assembled in and on the cylinder head.
- The timing gears, chain or toothed belt (not shown).
- Auxiliaries: water and oil pumps; injection and ignition (petrol engine) systems with their drive.
- The casings and oil sump which close the engine as well as the intake and exhaust manifolds.
- Miscellaneous parts such as bearings, studs and other fasteners, rings and gaskets.
- More and more engines have their main bearings cups integrated in a bedplate, like the Volvo D5 below. The picture shows the bare cylinder head casting on the right and the cylinder bloc on his bedplate on the left. The two parts join on the plane of the crankshaft axis and are fastened together after introduction of the crankshaft.