The purpose of the engine is to convert Petrol or Diesel into motion so that your car can move. The core of the engine is the Cylinder with the Piston moving up and down inside the Cylinder. The engine also consists of many different key parts which are Spark plugs, Valves, Piston, Piston rings, Connecting rod, Crankshaft and the Sump. All of these in good working order will create a perfectly operating engine which is the end result of a moving vehicle.
