What is the difference between petrol and a diesel engine?

            Engines that burn fuel inside them are called internal combustion engines. A petrol engine injects fuel into a cylinder and ignites it with a spark. The mixture of fuel and air explodes and drives a piston down the cylinder. The piston is connected to a crankshaft, which turns as the piston moves down. As the crankshaft continues to revolve, it pushes the piston up again.

            A diesel engine works in the same way, except that a spark is not needed to ignite the fuel. Instead, the engine is spun over by a starter. As the piston comes up the cylinder it compresses the mixture of diesel oil and air. Compressing the mixture heats it up and it explodes, driving the piston down.

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