Automobile Engineering MCQs

291. The compression ratio in petrol engine is kept less than in Diesel engine because

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it makes petrol engines lighter
higher or equivalent compression ratio in petrol engines is not possible due to pre-ignition
less compression ratio gives better performance
it is just customary to have less compression ratio in petrol engines
✅ The correct answer is option B.

294. In a spark plug, when the temperature of the central electrode exceeds a certain temperature, any carbon that has adhered will be burnt off, and the temperature at which this burning off carbon starts is referred to as the self cleaning temperature.

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Correct
Incorrect
✅ The correct answer is option A.

299. It is necessary to maintain the valve clearances as they

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reduce the resistance to sliding that occurs between the cam and the tappet
allow for lengthening of the valves owing to the heat of combustion
increase the speed at which the valves move up and down
make the crankshaft turn smoothly
✅ The correct answer is option B.