Drive train power loss

I worked at an engine dealership, and ran the wheel dyno, the specification is 82% of engine power will go to the ground on a normal unit.
What I did was find an industrial area with a slight hill and a long run out, take the truck to 30 miles an hour to the top of the hill and take it out of gear and coast, remember where you got to after every repair test it, if it slows down early then you want to look for a dragging brakes, bad bearings what ever.
Just a thought!

 

We looked into this a few years ago when we were having problems with our cummins isx 550. Had our rep look into original factory dyno report and he said it was a 550hp not a 600 we thought was in the truck.
Anyway cummins dyno at shop tested at 465hp on the ground. with 11R24.5 Bridgestone 726. 18spd with 4:10 ratio. Cummins said it was well within spec and more on the strong side! Hope this helps.

 

Constant losses These losses are neither dependent on the transmission's speed nor the load, i.e. they are constant. One example of elements causing constant losses is pre-loaded bearings. Due to the pre-loading, there is a constant friction force reacting to the rolling movement in the bearing. The pre-loading is in turn dependent on the temperature variations of the housing (gearbox, rear-axle, etc).

Speed losses Speed losses increase with the transmission's speed and are, for example, caused by windage effect on rotating parts. These losses are greatly influenced by the type and temperature of media (oil-air mix) in which the parts rotate.

Load losses As load increases so do the load losses. Load losses are mainly friction losses from the transfer of force from one gear to another. The greater force applied the greater the loss. If loaded in the normal direction: The load losses are approximately 1.0-1.5% / pair of gears for normal gears. The load losses for a pair of hypoid gears are approximately 2%


Caterpillar NZ is using 10% loss with stock engine at about 600 hp, 18 sp and twinscrew.