John Hennessey has a special treat for Chevy truck fans out there. The man whose company brought the world such hits as the Venom GT and Velociraptor, as well as kit upgrades for late model cars like the Camaro, Corvette, and MP4-12C is here again to show us what’s been going on at his business in Sealy, Texas.
In this case, the subject at hand is the 2014Â GMC Sierra, packing a hefty L86 Ecotec 6.2L V8 under the hood that generates 420 horsepower and 460 pound-feet of torque, which translates to about 336 horsepower and 368 pound-feet of torque at the wheels. Not too shabby on its own, but a man like Hennessey won’t stand to see those numbers stay the same, especially when it’s sitting right inside his shop.
He explains that the Sierra is here to test the features of the new HPE 650 system, which adds a 2.9L TVS supercharger up top, while supporting mods serve to increase the V8’s ease of breathing: “High-flow cylinder heads, an upgraded camshaft, [a reprogrammed] engine management computer, and we’ve also added a stainless steel exhaust system to the [vehicle] to give it a little bit more sound,” said Hennessey. “It’s probably worth about ten more horsepower…and it lets you know there’s something different about the truck.”
Left: the 2.9L supercharger helps increase the motor's output significantly. Right: the dyno graph displays 540 horsepower and 539 pound-feet of torque following the installation.
Dyno results show just how much the truck has improved, as it now makes 545 horsepower and 539 pound-feet of torque. Just for good measure, however, Hennessey takes the truck to an unofficial drag race on the company testing grounds, where he pairs it up against a stock 2014 Silverado.
Needless to say, the Silverado bites the dust with every pass, as the Sierra tops out at a consistent 110 miles per hour with excellent acceleration. So goes the awesome work atmosphere at Hennessey Performance; maybe next time we’ll see what’s in store for the 2015 Colorado and Canyon? One can only hope.