In many ways the diesel engine is a variation on the standard four stroke internal combustion engine, which has been used to power motor cars for over a hundred years. The man credited with its invention was Rudolf Diesel in 1897.
The four strokes of the conventional engine are inlet, compression, ignition and exhaust. The inlet stroke takes in petrol and air, which is then compressed and ignited by a spark plug. The difference with a diesel engine is that there are no spark plugs. The inlet valve takes in air and the fuel, a heavier grade than petrol, and the piston compresses it in the cylinder. The compression causes the mixture to become so hot that it ignites.
The diesel engine has many advantages over its petrol counterpart. There are fewer moving parts to go wrong, making them more reliable. Also, a typical diesel car will travel over sixty miles to a gallon, compared with around forty miles for a petrol version. In addition, diesel fuel is cheaper than petrol in many countries. Another bonus as society becomes more ecologically aware is that the diesel engine burns its fuel more efficiently than a petrol engine, making the exhaust gases less environmentally damaging. Their only disadvantage is that they are more expensive to buy, although the engines normally last much longer than petrol engines, making them a very good long-term investment, especially for high mileage drivers.
