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One In A Million: Playing With The 2017 GMC Sierra HD Denali Duramax Trucks

Posted in Features on May 4, 2017
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Photographers: Courtesy of GMC

Since 1908, GMC has been providing customers with products intended to do work. Namely, trucks and sport/utility vehicles, and in those 109 years the end goal hasn’t changed much, although the product has evolved significantly. GMC is poised as General Motor’s high-end luxury truck name with the Denali as its premium level trim package. GMC Denali trucks sell with the highest average transaction price and high levels of brand loyalty (so for a more discriminating consumer who prefers GM products).

The bold Denali grille lets others know you’ve arrived. The hood scoop is functional, ducting cool air into the 6.6L Duramax turbodiesel engine.

The figurative elephant in the room, and the main focus of this article, is the new-for-’17 Duramax diesel found in the Sierra HD 3/4 and 1-ton trucks. Data shows that 90 percent of Sierra HDs are sold with a Duramax and 60 percent of ’17 Sierra HDs sold are Denali models. The Denali trim package wraps you in leather and the finest interior options, and we’ll get back to that later. For now let’s get back to the Duramax. This new engine ups the game, keeping GMC relevant in the diesel truck power war. The big three OEMs bring to battle tow ratings, horsepower, and torque numbers and we, the consumers, all win. After all, who can’t use more power, torque, and towing capacity?

GMC invited us to drive several Sierra HD 4x4s, in both 2500 and 3500 ratings with a variety of load conditions. All of the trucks were decked out with Denali trim packages. One million Denalis have been sold since 1999—that’s more Denalis than Jaguar sells cars and Land Rover sells SUVs.

The ’17 Duramax is all new although the bore and stroke remain the same. The 90 degree V-8, known as the L5P, has new key upgrades to the block, a new cylinder head design, new pistons and piston pins, a new forged crankshaft, new connecting rods, a new variable valve turbo, new fuel system and more, all to help it deal with more pressure (more boost) and higher EGTs. The end result is a class leading 445 hp and 910 lb-ft of torque at 1,600 rpm, right where you want it. The upgrades help deliver more power, more torque, and better emissions. Also, the upgrades don’t end there: there are improvements to the Allison 1000 transmission’s torque converter and added beef to the yokes and drivelines. This helps deal with the higher torque and horsepower numbers as well as a more efficient exhaust brake.

We recently got a chance to drive and ride in several GMC Sierra HD Denali trucks with the new Duramax Diesel, and the experience allowed us to get a good idea of what the average GMC Sierra HD Denali owner does with their trucks. We were able to experience towing trailers (even really big ones), as well as driving loaded and unloaded trucks through various scenic areas of Utah and Colorado, up and down grades, and even spend a little time with the trucks off the road. That’s how GMC thinks its vehicle owners use their trucks, and we agree. Check it out.

Also on hand for a little four-wheeling was a Sierra HD All Terrain X. This off-road package features all-terrain tires, a rear automatic locking differential, unique grille, body-colored bumpers, and more.

Specifications (as tested)

Vehicle: ’17 GMC Sierra HD Denali 3500 4x4 DRW
Vehicle type: Crew Cab
Base price: $56,965
Price as tested: $68,940
Engine: 6.6L Duramax turbodiesel
Transmission: Allison 1000 six-spd automatic
Horsepower @ rpm (hp): 445 @ 2,800
Torque @ rpm (lb-ft): 910 @1,600
Curb weight (lb): 6,689
Payload (lb): 4,930
Towing capacity (lb): 23,300 when properly equipped
EPA mileage rating: N/A

What’s Hot: That horsepower and torque!

What’s Not: The DEF tank hangs low and looks like an afterthought.

We have had personal experience with these all-terrain tires found on the Sierra HD All Terrain X (LT275/65R18 Goodyear DuraTrac MTs). Goodyear makes a great off-road tire and DuraTracs are second to none. We also dig the color matched wheels.
The Sierra All Terrain X also includes the famous Z71 off-road suspension that includes twin-tube Rancho shocks, skidplates, hill descent control, and special info graphics in the Driver Information Center (a tip meter!). The rear axle also holds an Eaton automatic locking differential.
We like our trucks dusty and with a full plate of “off-road package.”
Anyone considering the Duramax diesel has to be interested in how these trucks tow. We got a chance to run several trucks through their paces with different trailers and full cargo beds. GMC knows that most of their customers will spend time towing heavy trailers so many of the improvements to the truck are aimed at towing with confidence. The trucks hit the mark and with the trucks in tow/haul mode and the exhaust brake turned on we were able to hit some extreme Colorado grades without worry.
The interior of the Sierra HD with the Denali package is amazing. Like a fancy hotel room in a destination town, every amenity is at hand. We’ve spent time in all of the big three’s 2017 high-end trucks and the interior of the GMC is this editor’s favorite of the bunch. Controls are laid out intelligently and everything is easy to use.
Under the hood the 6.6L Duramax is a tight fit. We like the functional hood scoop that is designed to introduce cool air while keeping out rain and bugs. The power of this engine is awesome with 445 hp and 910 lb-ft of torque.
These trucks are available with gobs of features and can be set up for towing, off-road use, and snow plowing right from the factory.



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