2024 Duramax Dyno

Huntindog wrote:

4x4ord wrote:
It would have been interesting to see what happens to the torque had they used manual mode and left it locked in 7th as it pulled down to 1800 rpm. It’s possible, even likely, that peak torque is achieved by 1800 rpm and the torque curve is flat from 1800 to 2000 or 2100 rpm.

It’s interesting that 420 peak rear wheel HP is obtained at 2800 rpm which is about 89% of the engine’s rated hp. (Indicating an 89% driveline efficiency) At 2150 rpm the truck is putting down 899 lbft of torque. If you use the same drive line efficiency of 89% the crankshaft torque would be 1010 lbft of torque at 2150 rpm. The engine is only rated to put out a peak torque of 975 lbft and that is at 1800 rpm.

Doesn't TQ get multiplied by the gears?

It does. The dyno numbers are derived from the rear wheel hp and represent crankshaft torque less driveline loss. For instance if the dyno rollers are spinning 1800 rpm when the engine is at 2800 rpm the roller torque would be 1225 lbft when the dyno is indicating 420 rear wheel horsepower. The torque value of 788 lbft that Banks is talking about is based on an engine speed of 2800 rpm though. (1225 roller torque x 1800 roller rpm / 5252 = 420 hp x 5252/ 2800 engine speed = 788 lbft crankshaft torque)