Engine torque @ Idling

[Shrikrishn a]

What will be frictional torque at idling speed will it be lower or higher than the engine torque at idling speed?
how to calculate the engine torque at idling?

 

[BrianPetersen]

Zero.

Draw a free body diagram. There are no net torques being applied to anything outside the envelope. How can the net torque be anything other than zero?

The torque produced by net positive pressure against the pistons precisely overcomes the torque required to overcome friction and fluid pumping losses.

 

[Shrikrishn a]

It was really helpful Brian. Thank you.

 

[LittleInch]

Depends on whare you draw the line / envelope surely?

An engine with no ancillaries powered from it then its zero.

If the ancillaries are outside the envelope ( water pumps, lube oil, steering pumps, alternators, A/C pumps, automatic transmission losses ) then no

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[enginesrus]

If you need frictional torque (torque to overcome friction), remove the spark plugs and turn the engine crankshaft with a dial torque wrench. If it was motored (reading motor load) depending on the speed then you introduce air movement, pumping etc.