Comparison of Petrol and Diesel Engines:
- In Petrol engine, a mixture of air and petrol is drawn into the cylinder and compressed, whereas in diesel engine, air alone is compressed
- Compression ratio in Petrol Engines (9 – 11) is quite less as compared to Compression ratio in Diesel Engines (15 – 24) which results in higher thermal efficiency and consequently about 30 to 40 percent saving in Fuel consumption in case of Diesel Engines
- Diesel is cheaper and less volatile than Petrol, which means lesser running cost and reduced risk of fire
- Because of relatively lesser speeds and also robust construction in case of Diesel engines, wear and tear is reduced
- Higher combustion efficiency of Diesel engines means less Carbon Monoxide and Hydrocarbons, but NOx and particulate matter has been a problem in their case. The same, however, has been almost remedied with the help of latest techniques. Co2 emission is also less in Diesel Engines.
- High and more stable torque over a wide speed range in case of Diesel engines. In modern common rail direct injection Diesel engines, more torque is available even at low engines speeds, than the comparable Petrol Engines
- Only disadvantage of modern Diesel engines is the higher initial cost. Use of CRDI technique has also reduced the noise in Diesel engines, which used to be a big handicap for their automotive applications. Even governor, which used to be a necessity in Diesel engines, in no longer required due to electronic control
- Starting aids like heater plugs are required in Diesel Engines
Firing Order:
In 4 – Cylinder Engines: 1-3-4-2 or 1-4-3-2
In 6 – Cylinder Engines: 1-5-3-6-2-4
In V- 8 Engines: 1-8-4-3-6-5-7-2
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