Under The Hood

In this post, we would like to blog about some basic and important engine parts and their function that you need to know as a step to understand about the reciprocal internal combustion four stroke engine. Thus you would know and understand on when the valve train system play their important role in an engine. Before getting into more complicated internal parts, let have some introduction about major external parts which can be observed under the hood.

Cylinder head

Starting from the top it would be head cover (the parts with manufacturer’s emblem or valve quantity) .As its name, this part used to cover the head and all parts that fix into the head. Then comes the cylinder head which colloquially known as head which sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, and that allow the exhaust to escape. The head can also be a place to mount the valves, spark plugs, and fuel injectors(we’ll go through topic in another post later). You can see some of the parts in the above figure since that is a cylinder head with removed head cover.

Cylinder Block

Cylinder block named after its structure since initially this part of engine is a block made of cast iron with cylinders which act as the combustion chamber. Well, after years of development, these days the cylinder structure become more advance with more complicated structure improving the design and efficiency. Presently, most of the cylinder block built with water jacket filled with mixed of water and coolant for the cooling system preventing overheat. From inline, boxer and v form, the cylinder block built anticipated the manufacturers needs for their desired performance.

Crankcase

An intrinsic component of a reciprocating type internal combustion engine, the crankcase is a drilled metal frame that houses several parts, notably the crankshaft. Its main universal function is to shield the crankshaft and the connecting rods from debris. In simple two-stroke engines, the crankcase serves several roles, and is used as the pressurization chamber for the fuel-air mixture. In more complex four-stroke designs, it is sealed off from this mixture by the pistons, and instead works mainly to store and circulate oil. In a four-stroke engine, it sits below the cylinder block, and in both types comprises the largest physical cavity of the motor. Most modern crankcases are made out of aluminum alloy, which provides a lightweight yet strong design capable of withstanding the pressures exerted during normal engine use. In normally aspirated four-stroke engines, that is engines that do not feature a turbocharger, a small level of pressure in the case is desirable to keep out dust and other potentially damaging particulates, while keeping the oil properly situated. All engines, as part of their normal operation, allow a small amount of unburned fuel and exhaust gas to escape into the crankcase. This collective material is known as blow-by.