The Truth Behind the HUMMER EV's Torque Figure
The specs on the all-new HUMMER EV are impressive. A HUMMER truck that can go 0-60 in 3 seconds, zero emissions, 350+ miles before having to recharge, 1,000 horsepower, on top of features such as Crabwalk, Super Cruise, etc. One number that does stand out among the impressive stats is the astronomical torque figure of 11,500 lb/ft of torque. A number that rivals GM’s 3500HD trucks.
Why is Torque Important?
Torque is force over time. Motor torque, which is the figure commonly reported by manufacturers is a measurement of the amount of rotating force produced by the motor. The HUMMER numbers are different because they report the rotating force at the wheels.
Car companies love to brag about a truck's torque specs because the greater the torque the more capable it could be. The more torque you have the you more toys you can haul and the more rocks you can crawl.
What's Wrong with GMC's Number?
The problem is that the 11,500 number reported by HUMMER is likely to be wheel torque. Unlike engine torque, wheel torque is calculated by multiplying the engine torque by the HUMMER’s gear ratio(s), the first gear and final drive ratio.
GMC’s Sierra 3500HD with a 6.6L turbo diesel V8 makes 910 lb/ft of engine torque and has a towing capacity of 14,500 lbs. Even GMC uses the 910 lb/ft of torque as their reported torque figure. (Click here to read all about the 6.6L V8 turbo diesel L5P Duramax)
If you were to get a torque number for the Sierra 3500HD that GMC uses to brag about for the HUMMER EV you would multiply 910 by the 1stgear ratio (3.09) and the final drive (3.73) to get 10,448 lb/ft of torque. An insane number if it was at the crank but that is not the case.
Do the Math
Now that we know the wheel torque, you can take that number to do the math backwards. Ready for an algebra lesson?
If x = motor torque
13.3 = front motor ratio
10.5 = rear motor ratio x2
11,500 = x(13.3) + 2x(10.5)
Skipping the work, x = 335 lb/ft per motor. The HUMMER EV has 3 motors so 335 x 3 = a more down to earth number of 1,000 lb/ft torque. Still impressive but a far cry from the earth spinning figure of 11,500 lb/ft.
While the 11,500 lb/ft of torque claim isn’t a lie—t’s just not the motor torque, which is the standard that torque is measured from. Does that mean that the HUMMER EV will be able to tow nearly as much as GM's 3500HD truck? Possibly, but definitely not as far. But the HUMMER EV doesn't necessarily have a crank since electric motors are are directly attached to the wheels.
Do you think it's fair to claim EV motor torque and compare it to a traditional internal combustion engine? Would 1,000 lb/ft of torque vs 11,500 lb/ft of torque change your mind about the HUMMER EV?
