2017 One-Ton Heavy-Duty Pickup Challenge: Dynamometer
By Mark Williams
At PickupTrucks.com, we like to find out how much power a drivetrain is putting out at the rear wheels for our Challenge comparison tests. The test results give us an idea of how they compare with factory horsepower and torque ratings. Sometimes that can be quite telling.
2017 One-Ton Heavy-Duty Pickup Challenge
Overview | Track | Towing | Daily Driving | Dynamometer | Results
Given that our 2017 One-Ton Heavy-Duty Pickup Challenge featured two of the biggest, most technologically advanced and most powerful turbo-diesel engines we've ever tested together, we hired Las Vegas Mobile Dyno to meet us at the Las Vegas Motor Speedway, where we conducted our customary empty and loaded track testing.
Here's What We Found:
Our 2017 GMC Sierra 3500 Denali with the all-new Duramax V-8 recorded 383 horsepower around 4,100 rpm and 786 pounds-feet of torque at 3,000 rpm. Both of those numbers match up pretty close to what we found several months ago with the same powertrain combination when doing dyno testing for our 2017 3/4-Ton Premium Truck Challenge. For that test, our 2017 Chevrolet Silverado 2500 LTZ Midnight Edition with the same Duramax engine and Allison 1000 six-speed transmission combination recorded 385 hp and 775 pounds-feet of torque. Consistency is good.
However, when it was the 2017 Ford Super Duty F-350 Lariat's turn on the dyno with its turbo-diesel 6.7-liter V-8 Power Stroke and six-speed transmission, our Las Vegas Mobile Dyno technician had some problems getting full power out of the engine, at least compared with the numbers we recorded during our Premium Truck Challenge. During that contest, the Ford's dyno runs — completed on a cool January afternoon with an in-ground Mustang dyno — yielded 369 hp and 721 pounds-feet of torque from a 2017 Ford Super Duty F-250 King Ranch with the same engine. This time, however, with our one-ton F-350 Lariat dually, we had to work hard to get 360 hp (admittedly close to our previous number), but in the torque department, our best pull gave us a max rating of 663 pounds-feet — quite a bit less than in the recent past.
After contacting Ford and providing representatives with as much information as we could, as well as discussing the processes and recollections from the Las Vegas Mobile Dyno technician, we could not determine how our numbers could differ by nearly 60 pounds-feet. We should note, as any good dyno or powertrain expert will tell you, that there always will be some disparity between different dynamometers and even between drivers, based on their experience. We'd also throw in that we've seen a moderate range in outputs when temperatures and/or cooling fans (sometimes pointed incorrectly) have not been the same between trucks, providing a wider margin than expected.
We can only assume that one of these variables, or a combination of them, could be the culprit here. We used the same dyno with the same methods and tester on the same Dynojet equipment for each truck within an hour of each other on the same day at the same location — and this was the result.
Cars.com photos by Evan Sears
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