This section looks at major components of the 4-stroke and 2-stroke petrol engine. Because they operate on similar principles, many of their components are similar too.
For example, their engine blocks both operate under working conditions of very high pressures and temperatures, and new designs and materials to make them work more efficiently are always being tested.
Many vehicles still use cast iron, but some have aluminum alloy blocks. The main gain is a saving in weight. Aluminum alloys can be made as strong as cast iron, but they are lighter. This is also true for cylinder heads.
Combustion chambers in the cylinder head come in many different designs.
To help hold in the extreme heat and pressure of combustion a seal is made between the block and cylinder head by a head gasket.
The 4-stroke petrol engine has other passages cast into the head to carry oil for lubrication and coolant for cooling.
