Transmission losses on dyno

I have no problem with you, and I do understand your point completely.. And i agree with you.. I have never fully under stood how a blanket % 10 to 20 or whatever, could be used for every truck when there are so many variables... I agree with you that the only true way to come up with an accurate loss is to measure each truck, that is somthing that i didnt know could be done until i read your post..My point was that on the dynos ive seen there can be other factors other than drivetrain that can affect % of loss.. I completely under stand that its mesured mechanically at the rollers, but are there not outside factors that can affect the mesured load? Both the local dyno's operators that are owned by the same co. say there can be variables.. If there is a condition that could affect output by as little as say 1-4% coupled with a blanket correction of 20% or 10%, that would make results even more inacurate than just a blanket correction... Forget the water... What if there was a factor any factor that could cause a flawed result, the only true way to get an accurate result would be to do what what you stated, measure loss then run immediately after.. That's all I was tryin to say in my post (granted it was a much shorter version) ... As for the Mr. haney thing, that was a very poor atempt at a comparison, seemed like ( to me at the time) that you glossed over his post without understanding what he posted, like I felt mine was.. That was my perception, which was most likely wrong.. Shouldn't have posted that...To be honest it seemed (to me) that you quickly dissmissed any one whose opinion varied from yours, not that you did but maybe i misunderstood.. I do appolgize for highjacking your thread with my nonsense... No bs -sorry-.. have a nice day

 

I ran a dyno at an engine dealership and lots of engines would have a printout of them being dyno'd before they would be put back in the truck. We had a 4 roller dyno so it allows the power to the ground threw the easiest route. Setting a dyno to the proper calibration is not that hard you hang a weight on a rod and it should read a certain value. A truck looses 18%, if it looses more than that then there is a problem, The newer trucks may have a higher loss due to a larger fan. Just a thought!

 

So is it a more or less set hp loss? or does the losses get larger or smaller (proportionatly) with more HP.

Will a 1000hp truck still loose 18%?

or will it be less?

A 550 takes 100hp

does a 1000hp take 200? Or only 150?

Hope you all get what I am trying to say?

 

Loses aren't pure percentages. Its just the lazy man's way of guestimating engine HP and likely over-estimating it.

Its all about the physics of whats happening. Fan loss is fixed unless you change the pulley ratio. Transmissions friction losses are proportional to the torque so not a percentage of HP.