of the engine cover is composed of two parts, the cylinder block and a cylinder, connected to each other by means of bolts.
block material should have sufficient strength, good castability and machinability, and the price is low, the common block material is cast iron, alloy cast iron. However, using an aluminum alloy cylinder becoming more common, because light weight aluminum alloy cylinder, good thermal conductivity, the capacity of the coolant can be reduced. After starting, the cylinder rapidly reaches its operating temperature, and the thermal expansion coefficient of aluminum pistons and exactly the same, a small gap variation after heating, can reduce the impact of noise and oil consumption. And the head and thermal expansion of the same alloy, cold working can reduce thermal stress generated by the impact.
