1. Fuel Injection: In a petrol Engine the air and fuel are mixed outside the cylinder in a carburettor and the mixture is fed to the engine cylinder. Whereas in a diesel engine, fine spray of fuel is injected to compressed air inside the cylinder.
2. Compression Ratio: The air in diesel engine is compressed far higher than the air-fuel mix in a petrol engine. This enables the diesel engine to convert more energy of the fuel to work. Compression ratio for a diesel engine is approx 16:1 and that of a petrol engine is not higher than 10:1.
3. Spark plug and Fuel injector: A petrol engine is fitted with a spark plug, but it is replaced by a fuel injector in diesel engine.
 Fuel Injector in a diesel Engine |  Spark plug in a petrol Engine |
4. Working Cycle: The petrol engine works on Constant Volume Cycle (Otto Cycle) and the diesel engine works on Constant Pressure Cycle.
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5. Use: Diesel engines are mostly used in heavy vehicles like trucks, buses etc. whereas a petrol engine is used in comparatively lighter vehicles like cars, scooters etc.
6. Fuel Consumption: The rate of fuel consumption is less in a diesel engine compared to petrol engines.
7. Weight: Diesel engines are heavier than petrol Engines.
8. Running Cost: The running cost of a diesel engine is lesser than a petrol engine.
4 comments:
thanks. it really helped me
Was trying to find the basic difference between petrol engines and diesel engines. Thanks a lot for maintaining this blog and updating it.
Thanks for the post about petrol engine and diesel engine.
Very informative post about petrol engines and diesel engines!
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