Internal Combustion Engines
The ratio of the indicated thermal efficiency to the air standard efficiency is known as

Relative efficiency
Mechanical efficiency
Volumetric efficiency
Overall efficiency

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Internal Combustion Engines
Detonation is harmful due to

Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine
High intensity of knock causes crankshaft vibration and the engine runs rough
Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls
None of these

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