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Mechanical Engineering Objective Questions { Internal Combustion Engines }

127. According to Recardo's theory, detonation occurs due to
A.Instantaneous auto-ignition of last part of charge to be burnt
B.Improper mixing of air and fuel
C.Improper combustion
D.Self ignition temperature has nothing to do with detonation

128. A fuel will detonate less if it has
A.Higher self ignition temperature
B.Lower self ignition temperature
C.Proper self ignition temperature
D.Self ignition temperature has nothing to do with detonation

129. The knocking in diesel engines for given fuel, will be
A.Enhanced by increasing compression ratio
B.Enhanced by decreasing Compression ratio
C.Unaffected by compression ratio
D.First enhanced by increasing compression ratio upto a limit beyond which it will be suppressed

130. The ignition of charge by some hot surface in the engine cylinder before operation of spark plug is known as
A.Auto ignition
C.Retarded ignition
D.Accelerated ignition

131. Injection lag is
A.The time taken by fuel after injection (before top dead centre) to reach upto auto-ignition temperature
B.Time before actual fuel injection and the pump pluger starts to pump fuey
C.Time corresponding to actual injection and top dead centre
D.Time corresponding to actual ignition and top dead centre

132. Ignition quality of diesel-fuel oil is ex, pressed by an index called
A.Octane number
B.Cetane number
C.Calorific value
D.Carbon content

133. Carbon residue in diesel oil should not be more than

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