Part 6 - The Cylinder and head - basics

The Cylinder (AC)

 

The cylinder is where the ‘magic’ happens so to speak. It contains the ports to manage the fuel/air and exhaust gases (which well cover later) and houses the piston, rings and spark plug. The cylinder has been be hard wearing, able to handle high pressure and heat. The cylinder pictured above has cooling fins to help cool the cylinder down.

Other names for the cylinder are ‘barrel’, ‘bore’ and ‘sleeve’ but we’ll stick with cylinder. Cast into the cylinder are ports which we covered earlier. The diameter of the cylinder is called the bore. This, as mensioned before is slightly larger than the piston. The cylinder wall has been highlighted blue below.

 

The cylinder head

 

The CYLINDER HEAD is basically the ‘cap’ to the cylinder. It is sometimes called the ‘Cap’ but we’ll stick with just HEAD. The cap has an underside called the COMBUSTION CHAMBER which has a very destinctive shape. 

This is where the burning (combustion) of the fuel/air mixture takes place. The head also holds the SPARK PLUG in place. The location of the spark plug is place in the centre of the combustion chamber. The combustion chamber is highlighted in blue.

 

On top of the head are cooling fins to help transfer heat just like the cylinder. You can see 4 holes in the head which allow the head to be bolted to the cylinder.