Engine Friction

·         The bearing friction includes the friction due to main bearing connecting rod bearing and other bearings.

Answer: True

·         Bearing friction is viscous in nature and does not depends upon the oil viscosity, the speed, size and geometry of the journal.

Answer: No, actually, bearing friction is viscous in nature and depends upon the oil viscosity, the speed, size and geometry of the journal.

·         The valve gear friction losses vary with the engine design variables and no general equation is available predicting them.

Answer: True

·         The blow by losses is the phenomenon of leakage of combustion products past the piston and piston rings from the cylinder to the crankcase.

Answer: True

·         Blow by losses depend on the outlet pressure and compression ratio.

Answer: In fact, blow by losses depend on the inlet pressure and compression ratio.

·         Blow by losses vary as the square root of inlet pressure, and increases as the compression ratio is

Answer: increased

·         Blow by losses are reduced as the engine speed is

Answer: Blow by losses are indirectly proportional to engine speed and it is reduced as the engine speed is increased.

·         A rise in cooling water temperature ____________ engine friction through its effect on oil viscosity.

Answer: reduces

·         Higher the oil viscosity ____________ is the friction loss.

Answer: Viscosity is proportional to friction loss, so higher the oil viscosity greater is the friction loss.

·         As the load increases the maxim,um pressure in the cylinder has a tendency to increase slightly.

Answer: True