Mechanical Engineering Objective Questions { Internal Combustion Engines }

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71. Supercharging is essential in

A. Diesel engines

B. Gas turbines

C. Petrol engines

D. Aircraft engines

72. The minimum cranking speed in case of petrol engine is about

A. Half the operating speed

B. One-fourth of operating speed

73. In a typical medium speed 4 stroke cycle diesel engine

A. Exhaust valve opens at 35° before bottom dead centre and closes at 20° after top dead centre

B. Exhaust valve opens at bottom dead centre and closes at top dead centre

C. Exhaust valve opens just after bottom dead centre and closes just before top dead centre

D. May open and close anywhere

74. Flash point of fuel oil is

A. Minimum temperature to which oil is heated in order to give off inflammable vapors in sufficient quantity to ignite momentarily when brought in contact with a flame

B. Temperature at which it solidifies or congeals

C. Temperature at which it catches fire without external aid

D. Indicated by 90% distillation temperature, i.e. when 90% of sample oil has distilled off

75. The mean effective pressure obtained from engine indicator indicates the

A. Maximum pressure developed

B. Average pressure

C. Instantaneous pressure at any instant

D. Exhaust pressure

76. For the same power developed in I.C. engines, the cheaper system is

A. Naturally aspirated

B. Supercharged

C. Centrifugal pump

D. Turbo charger

77. Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power

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