See GMC Sierra Denali HD Diesel With Mild Mods Roll Coal On A Dyno

Diesel truck lovers and Hoonigan fans, here’s the episode of Dyno Everything you’ve been waiting for. It doesn’t feature a fire-breathing engine boosted to the stratosphere, nor is it rolling with a ginormous suspension lift. What we have here is a good ol’ GMC Sierra with some wheels, an engine tune, and according to the truck’s owner, that’s it.

To be specific, the truck in question is a 2020 GMC Sierra HD Denali packing the turbocharged 6.6-liter Duramax diesel V8 engine. Intercooler piping is upgraded, and it’s running a tune that goes to “stage five” per the owner, though parameters on the tune aren’t mentioned. Underneath, the suspension has a leveling kit with Fox shocks, and it all rides on Fuel wheels.

It’s a short list of modifications, but it’s enough to smoke out the dyno room on the truck’s first pull. The diesel is definitely running rich enough to roll some coal, though whether it’s an intentional tune for that or just a side-effect of extra power is unclear. A stock 2020 GMC Sierra HD Denali is rated at 445 horsepower at the crank, which equates to approximately 380 at the tire. The Hoonigans predict anywhere from 399 to 550 wheel hp, so in their eyes, the modifications make almost no difference or all the difference.

Of course, we know there’s also a third option – somewhere in between. And that’s pretty much what we get with the first run, laying down 467 hp. The second run with “more RPM” produces 478 hp, though the engine still cuts out at around 4,000 rpm. Similarly, the final run with “all the rpm” has the same cutoff, but it yields 481 hp.

But hey, this is a diesel so what about torque? Only the final run shows a torque figure, which is an impressive 771 pound-feet peaking at 3,100 rpm. Peak horsepower comes on at approximately 3,400, as you’d expect from a big turbo diesel. Presumably, the owner’s casual mention of spinning the Duramax to 7,000 rpm for more power at the end of the video is a joke.

We say presumably because he doesn’t seem happy with the diesel’s output. However, factoring in a parasitic drivetrain loss of 15 percent, we’re looking at roughly a gain of 100 hp. That seems pretty good for some pipes and a tune, but what do you think? Light up our comments with your thoughts on this unlikely Hoonigan dyno adventure.