The cylinder of an engine is the enclosure by which a piston moves. The cylinder name comes from its practically cylindrical form.
The materials used to make the cylinders are specific to each type of engine. The way of building and the chosen materials of the cylinder makes vary the performance of the engine. A cylinder made of a gray cast matrix with laminar graphite provides good sliding properties. A motor cylinder made of high quality alloys such as molybdenum, chromium, nickel and manganese, improves hardness and resistance to wear and corrosion.
These parameters determine the displacement or volume displaced by the movement of the pistons.
The compression ratio is the ratio of the cylinder's internal volume when the piston is at the low dead center and the volume at the dead center high.
Design and operation of the cylinder
In a thermal engine there may be a single cylinder (eg chainsaw motors) or multiple cylinders, up to 12 or 16, in the case of cars or airplanes.
Motors with more than one cylinder have the so-called engine block. In the engine block the cylinders are cast in a single block of aluminum or cast iron.
There is a relationship between the cylinders and the power of a thermal engine. The power of a motor depends on the amount of fuel that explodes inside the cylinder. Hence, the cylinders that allow to accommodate a larger volume of fuel have more power. The total cylinder capacity of a thermal engine is the volume displaced by the piston in each cylinder multiplied by the number of cylinders.