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GM exploring ways to raise half-ton Duramax diesel tow rating

Lots of truck owners cheered when GM announced fuel economy numbers for the 2020 Chevrolet Silverado with the 3.0-liter Duramax diesel inline-six. Even after Ram let loose its EPA mileage ratings for the 2020 Ram 1500 EcoDiesel, the Chevy oil-burner still took the trophy. The victory was years in the making, GM engineers spending an entire four-year development cycle refining the LM2 Duramax to increase mileage. The tradeoff, as well all know by now, is towing; the Duramax in half-ton duty pulls a maximum 9,300 pounds in the Silverado. Rivals across town can do more, the Ford F-150 PowerStroke rated at 11,500, the Ram 1500 EcoDiesel game to pull 12,560. GM engineer John Barta told Muscle Cars & Trucks that more hauling chops could be on the way, explaining, "We’re actually looking at upgrading some of the materials around (the engine bay) to see if we can maybe raise our tow rating." Engine bay materials are at issue due to thermal complexities underhood. John Barta, GM's assistant chief engineer of diesel engine controls, said the Duramax's inline-six configuration allowed engineers to get emissions hardware like the combined selective catalytic reduction, diesel oxidation catalysts, and diesel particulate filter unit closer to the engine, where it heats up quicker, getting emissions down quicker. But that filter puts another heat source in those confines, enforcing a cap on the tow rating to keep the engine and other systems from overheating. "If you look under the hood," he said, "youÂ’ll see a significant amount of silver ‘moon tapeÂ’ around to make sure things arenÂ’t getting overheatedÂ… if we were to go up in higher towing, which we can, we start impacting the possibility of deteriorating some of the components.” There isn't much space for more grille, so swapping for a better grade of "moon tape" or a different kind of material could reduce engine bay heat, extracting a higher tow rating in the process.  It's important to note a point Barta's been making for months about the Duramax figures, though. "Even though itÂ’s nice to brag about big numbers, in reality, light duty customers are not towing that large with their trucks," and, "We do know that (95 percent) of our light duty customers donÂ’t tow over 9,000 pounds." On our First Drive of the 2020 Silverado diesel we called out the tow rating, but emphasized that the Chevy and GMC have more important challenges to overcome.

2024 GMC Sierra HD AT4X and Extreme AEV muscle their way into the lineup

The new AT4X variant of GMC's 2024 Sierra HD pickup series officially joins the stable this week, giving pickup truck box-checkers yet another off-road trim to chase. Well, two trims, technically, as GMC took the opportunity to announce that the AT4X will also be offered with an upfit package from American Expedition Vehicles, appropriately named the Extreme AEV Edition that takes its cues from the same package offered on the Sierra 1500 AT4X. And with its introduction, the 2024 GMC Sierra HD lineup is now complete.  GMC's Sierra AT4X models mirror the ZR2 packages offered on the updated Chevrolet Silverado. If you paid any attention at all to the Silverado HD ZR2's introduction earlier this month, you'll be familiar with the formula. Key upgrades include a 1.5-inch factory lift, standard electronic locking rear differential, Multimatic DSSV shocks and 35-inch Goodyear Territory all-terrain tires. It also gets beefier skid plates —  both the steel protecting the transfer case and the aluminum piece up front. With the updated 6.6-liter Duramax diesel, GMC says it'll tow up to 18,500 pounds.  "GMCÂ’s AT4X trim, which will be available across the entire GMC truck lineup, offers customers more premium and capable choices when it comes to ‘do-it-allÂ’ capabilities," said GMC VP Duncan Aldred. "Each model delivers unique strengths, with the all-new Sierra HD AT4X taking it to the max, enabling you to go virtually anywhere, with the towing power to bring your recreational toys, gear or camper along for the journey." And by "do it all," he means all the luxury stuff too, judging by the Obsidian Rush interior, which GMC says includes massaging leather front seats and real ash wood trim. The better from which to feel the shove of the AT4's two available 6.6-liter engines, one a gasoline-burner rated at 401 horsepower and 464 pound-feet of torque, the other a Duramax turbodiesel making 470 horsepower and 975 pound-feet of torque. You'll need the latter if you want to hit GMC's advertised towing capacity.  And don't forget the Extreme AEV Edition, which will surely come with a Denali-rivaling (and still TBA) price tag. The stamped steel bumpers stand out right away, as do the integrated front recovery points and winch mount. The package also adds more skid plates protecting the steering gear and transfer case. Its 18-inch "Salta" wheels are also unique.  GMC says it will be cranking out 2024 Sierra HD AT4Xs and Extreme AEV Editions by the third quarter.

GM resumes production of its 3.0-liter turbodiesel straight-six

General Motors temporarily stopped taking orders for trucks and SUVs equipped with the 3.0-liter Duramax turbodiesel six-cylinder engine in August 2021 due to a supplier shortage. Reports claimed the pause would last through 2021, but the engine is already back in production. Enthusiast website GM Authority learned from sources inside General Motors that the straight-six is once again coming off the assembly line at the Flint Engine Plant in Flint, Michigan. There's no official word on precisely what the problem was linked to and whether it was related to the on-going chip shortage that's wreaking havoc across the automotive industry. All we know is that the pause lasted for about two weeks. Called LM2 internally, the six is available in Chevrolet's Tahoe, Suburban, and Silverado 1500 and in GMC's version of these trucks. It's also an option in the Cadillac Escalade. It develops 277 horsepower at 3,750 rpm and a V8-like 460 pound-feet of torque at 1,500 rpm in every application, and it allows these big behemoths to post surprising fuel economy numbers. Fitted to a rear-wheel-drive Tahoe, the Duramax returns 21 mpg in the city, 28 mpg on the highway, and 24 mpg in a combined cycle, figures that make it more efficient than a Blazer. Demand for the diesel-powered trucks is relatively high. While the shortage undoubtedly took a toll on sales, the Duramax represented 8% of Suburban sales and 6% of Tahoe sales in May 2021. There are no other diesel-burning full-size SUVs available new so they have the market to themselves. On the truck side, Ram still makes the EcoDiesel available on some 1500 trims but Ford abandoned the segment. Related Video: Featured Gallery 2021 Chevrolet Tahoe RST View 24 Photos Chevrolet GMC Truck SUV Diesel Vehicles