Petrol and diesel engine.

Diesel engine named after Rudolf Diesel. In a diesel engine no spark plug is needed. Diesel is sprayed into the cylinder with air. Because the air is at very high temperature immediately after compression, the fuel mixture ignites on contact with the air inside the cylinder and pushes the piston upward. The operation of a diesel engine is quite simple and it's efficiency is greater than that of petrol engine.

Petrol engines require a spark plug to ignite the fuel and air mixture. When fuel is injected in the cylinder through fuel injectors, it is compressed with air by pistons. Then the whole mixture of petrol and air is ignited by a spark plug. A spark plug fires the mixture causing a rapid increase in pressure and temperature. This mixture expands and forces the piston to move outward. Which delivers the power to the crankshaft to drive the flywheel.