Petrol vs Diesel engines: A comparison - Basic difference between a petrol engine and a diesel engine based on working, pressures, combustion, compression ratios, speed, efficiency, maintenance, and running costs. The following points are important for the comparison of petrol and diesel engines:
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Petrol Engines
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Diesel Engines
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1.
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A petrol engine draws
a mixture of petrol and air during suction stroke.
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A diesel engine draws
only air during suction stroke.
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2.
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The carburetor is
employed to mix air and petrol in the required proportion and to supply it to
the engine during suction stroke.
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The injector or
atomiser is employed to inject the fuel at the end of compression stroke.
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3.
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The pressure at the
end of compression is about 10 bar.
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The pressure at the
end of compression is about 35 bar.
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4.
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The charge (i.e.
petrol and air mixture) is ignited with the help of a spark plug.
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The fuel is injected
in the form of fine spray. The temperature of the compressed air (about 600°
C at a pressure of about 35 bar) is sufficiently high to ignite the fuel.
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5.
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The combustion of fuel
takes place approximately at constant volume. In other words, it works on Otto
cycle.
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The combustion of fuel
takes place approximately at constant pressure. In other words, it works on
Diesel cycle.
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6.
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A petrol engine has
compression ratio approximately from 6 to 10.
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A diesel engine has
compression ratio approximately from 15 to 25.
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7.
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The starting is easy
due to low compression ration.
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The starting is little
difficult due to high compression ratio.
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8.
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As the compression
ratio is low, the petrol engines are lighter and cheaper.
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As the compression
ratio is high, the diesel engines are heavier and costlier.
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9.
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The running cost of
petrol engines is high because of higher cost of petrol.
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The running cost of
diesel engines is low because of the lower cost of diesel.
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10.
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The maintenance cost
is less.
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The maintenance cost
is more.
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11.
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The thermal efficiency
is upto about 26%.
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The thermal efficiency
is upto about 40%.
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12.
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Overheating trouble is
more due to low thermal efficiency.
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Overheating trouble is
less due to high thermal efficiency.
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13.
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These are high speed
engines.
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These are relatively
low speed engines.
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14.
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The petrol engines are
generally employed in light duty vehicles such as scooters, motorcycles,
cars. These are also used in aeroplanes.
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The diesel engines are
generally employed in heavy duty vehicles such as buses, trucks and earth
moving machines etc.
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The basic difference in between a petrol and diesel engine, we learn in physics in school days. But afterward, when we are getting some practical example in our real life and get involved with different vehicles and different engines, we can understand their features and characters. Here this article also describes some essential facts and a suitable difference in between petrol and diesel engine. Thanks for providing such a beneficial information.
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