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Torque time | 2017 GMC Sierra HD First Drive

It's not the truck that counts, it's how you use it. It's the heavy stuff you fit in its bed or the extremely heavy stuff that gets hooked up to the tow hitch. The ATV, the Jet Skis, the trailer with more square footage than a Greenwich Village apartment. Perhaps you need to get Seabiscuit or, uh, Mr. Ed to wherever they need to gallop next. In our case, there's a pair of very serious-looking snowmobiles perched atop the bed of a GMC Sierra. They spread out as wide as the extended tow mirrors, and their back halves are dangling precariously beyond the truck. Sterling Archer would be giddy; I'm a little nervous. But only because canyon roads and wide vehicles with a high center of gravity go together like peas and custard. The added weight is no sweat at all. That's because this is the 2017 GMC Sierra HD Denali, a truck with the sort of enhanced power, torque, suspension, and stopping capability expected of a heavy-duty pickup. And for this year, the power and torque get a serious bump courtesy of a new 6.6-liter Duramax turbodiesel engine reengineered from almost the ground up with 90 percent new parts. It's quieter and more efficient and it emits less, while most importantly producing 445 horsepower and 910 pound-feet of torque. That's up from 397 and 765, respectively. Chevy fans will note that the same engine is also available in the updated 2017 Silverado HD. Now, for those keeping score at home, that horsepower is best-in-class but the torque number still falls short of the new Ford Super Duty and its Power Stroke diesel V8's 925 lb-ft. Aw shucks. For the record, GM's engineers didn't seem too concerned that they weren't able to eke out an extra 16 torques just to say they're No. 1. "We wanted to first meet emissions and then deliver the maximum horsepower and torque we could, and deliver it over the widest usability range possible," said chief engineer Eric Stanczak. And let's be honest here, 910 pound-feet is herculean, and once again, a jump of 145 lb-ft. Or one Subaru Impreza's worth. Or 110 more than the best Ram can do on a 2500, and its Cummins turbodiesel's 800 pound-feet was eye-popping not too long ago. (The Ram 3500 maxes out at 900 lb-ft with the right transmission.) Ah, but here's the rub. That Cummins-equipped Ram 2500 can still tow more weight according to SAE-compliant measurements – 17,510 pounds for a Ram crew cab with a short bed versus 13,000 in the similar Sierra 2500. The Ford F-250 can manage 15,000.

Chevy's 6.6-liter Duramax is pretty much all new

To say there's a heated battle in heavy-duty pickups is an understatement, with Chevrolet, Ford, and Ram constantly trading blows of increased torque, horsepower, and towing capacity. The latest salvo is the revised, more powerful turbo diesel 6.6-liter Duramax V8 in the 2017 Chevy Silverado. It has 910 pound-feet of torque, an increase of 145, putting it nearly level with the Ford Super Duty. Here's a closer look at where those gains come from. How exactly did Chevrolet add all that torque plus 48 horsepower? The automaker essentially took a fine-tooth comb to the entire engine. Chevy says it changed 90 percent of the V8, and the cumulative effect of those small changes adds up to big increases. As you might guess, the turbocharger is updated. The larger unit features electric actuation of the variable nozzle turbine (VNT), and what Chevy calls a double axle cartridge mechanism that separates the VNT moving parts from the housing. That helps with heat performance as well, with a claim that the exhaust side of the turbo can run continuously up to 1,436 degrees Fahrenheit. Helping that cause are six exhaust gaskets made of Inconel - an nickel alloy that contains chromium and iron – and upgraded stainless steel for the exhaust manifold. Despite having the same cast iron cylinder block, albeit with some minor enhancements, the engine has new cylinder heads, pistons, piston pins, connecting rods, and crankshaft, which have all been upgraded to handle 20 percent higher cylinder pressures. Alongside the increase in pressure, Chevrolet also increased the cylinder head's structure with a honeycomb design. The pattern features high-strength aluminum with dual layer water jackets that not only improve strength, but also optimize water flow for better cooling. For 2017, the cylinder head also benefits from integrated plenum that aids the engine in getting more air under heavy loads. The cylinder head isn't the only component to get a minor update, as the pistons have a larger diameter pin for improved oil flow. The same detailed improvements has been bestowed to the humble connecting rods (second in our hearts only to the inanimate carbon rod). The new design has the bolts oriented roughly 45-degrees to the rod instead of parallel. The angle split design, as it's called allows for easier passage through the cylinder.

2018 GMC Sierra 2500HD All Mountain concept: Nothing stops it in its tracks

Winter may not be the best time for sports cars, but snow and ice can still provide a ton of fun in the right vehicle. The Porsche Macan GTS I had back in January was a riot in the snow, and it was wearing nothing more than a good set of winter tires. What you really need to conquer the frozen north is tracks. These replace wheels with the same sort of equipment that helps tanks and snowmobiles roll over damn near everything in their paths. That's what makes the 2018 GMC Sierra 2500HD All Mountain concept so awesome. That and the 910 pound-feet of torque from the 6.6-liter Duramax turbo diesel V8. The All Mountain concept is set to debut this week in Veil, Colorado, home to ski slopes, log cabins and nearly year-round snow pack. The truck is based off a standard GMC Sierra 2500HD. The turbo-diesel V8 makes 445 horsepower in addition to the mountain of torque. Power is sent to all four corners through an Allison 1000 six-speed automatic. The new treads come courtesy of Mattracks. The 150 Series tracks aren't cheap — well into five figures with installation — but they give you a nice 16-inch surface at each corner. Other changes and add-ons include graphics on the bodywork, a RIGID E-Series 30-inch light bar, LEDs on the wheel well and underbody, Thule snowboard racks, a roll-up tonneau cover and a new speaker system from Kicker. The truck will stay on display in Veil all winter, though a similar concept will be making its way to various auto shows, starting with Los Angeles next week. Related Video: This content is hosted by a third party. To view it, please update your privacy preferences. Manage Settings. Featured Gallery GMC Sierra All Mountain Concept: LA 2017 View 9 Photos Related Gallery 2018 GMC Sierra 2500HD All Mountain concept View 10 Photos News Source: GMCImage Credit: Live photos copyright 2017 Drew Phillips / Autoblog.com GMC Truck Off-Road Vehicles