Engine Proper

[1] Cylinder, Cylinder Block
  A combustion chamber is made up of a cylinder, a cylinder head and a piston.    A cylinder has a cylindrical shape and its inner surface is perfectly finished.
  The piston slides up and down between top dead center and bottom dead center within the cylinder. The cylinder receives the most  complicated forces in the entire engine because of the influence of the pressure and heat generated by the burnt gas.

(1) Cylinder classification
Cylinders can be structurally classified into the following types: 
            
1) In-block cylinder  
    The cylinder and the cylinder block are manufactured as a solid unit.    Since no cylinder liner is used with an in-block cylinder, it has fewer parts than a liner type cylinder.  For this reason, this type is suitable for  mass production.  Currently, in-block cylinders are used most widely for gasoline engines with cast iron cylinder blocks.
2) Dry liner type
    The cylinder liner housing  of the cylinder block is finished into a cylindrical diameter with a fitting tolerance from the finished imensions of the cylinder.    A separately manufactured cylinder liner is inserted into this.  The cylinder liner is surrounded by the walls of the cylinder block, so it never comes into direct contact with the engine cooling water.

               
3) Wet liner type 
     The cylindrical part of the cylinder is made up entirely of the cylinder liner.    The outer surface of the wet liner comes directly in contact with the cooling water.
    For this reason, this type of cylinder liner can be cooled efficiently.   Wet liners are easier to manufacture and assemble than dry liners.     
     The upper part of the cylinder liner has a flange which is used for positioning during assembly and which prevents water from leaking from the top.    The lower part of the cylinder liner has a "rubber ring" to prevent water leakage.  Ordinarily, the liner thickness is 6 – 8% of the inner diameter of the liner.