Requirements of cooling

The heat energy which flows from gases to cylinder walls, amounting to 22 to 30% will raise the temperature of piston and cylinder walls.

If no cooling is provided, the average temperature attained by cylinder and piston will correspond to gas temperatures in the range of 1000°C to 1500°C which will cause the overheating of engine components.

Though these high temperatures will give higher thermal efficiency and reduced friction losses, however, such high temperature will damage the certain vital parts of the engine due to their mechanical expansion and distortion caused by thermal stresses.

Also, the cylinder lubrication will be impossible at these high temperatures. Therefore, it becomes necessary to provide cooling system to maintain the temperatures within certain limits to obtain the maximum performance from the engine.

Requirements of lubrication system

It should maintain the required oil film on the cylinder walls to prevent excessive wear of cylinder liners, pistons and rings.

Reduce the frictional resistance of the engine to a minimum to ensure maximum mechanical efficiency.

Protect the engine against wear.

Serve as a cooling agent by picking up heat.

Remove all impurities from the lubricated region.

Form a seal between piston rings and the cylinder walls to prevent blowby.