Diesel may be losing ground in some parts of the passenger-vehicle market, but Canadian heavy-duty pickup buyers are telling a very different story. General Motors says nearly 65% of Canadian buyers in the segment choose diesel, underscoring why the company is making one of its biggest heavy-duty engine moves in years.
For the 2027 Chevrolet Silverado HD and GMC Sierra HD, GM is introducing an all-new 8.3-litre Duramax turbo-diesel V8. The headline numbers are enormous: 555 horsepower and 1,230 lb-ft of torque according to GM’s corporate specifications and Chevrolet Canada. Yet the overhaul stretches well beyond the engine. Higher towing limits, electric rack-and-pinion steering, electronic brake boost and new trailering technology show how fiercely competitive North America’s heavy-duty pickup market has become.
Diesel Still Has an unusually Strong Hold on Canadian HD Buyers
Nearly 65% of Canadian heavy-duty pickup customers choose diesel, according to figures attributed to General Motors. That is notable at a time when much of the wider automotive conversation centres on electrification, hybrids and smaller gasoline engines. Heavy-duty pickups operate in a different environment. Contractors, farmers, equipment operators and owners pulling large recreational trailers can put thousands of kilometres on a truck while it is carrying or towing substantial weight.
The Canadian figure also fits GM’s broader picture of the North American HD market. The automaker says more than 60% of its heavy-duty customers choose a diesel engine. That helps explain why GM has committed substantial engineering and manufacturing resources to another combustion-powered truck engine even while investing heavily in electric vehicles. Diesel remains particularly valuable in this segment because high torque at relatively low engine speeds suits pulling heavy loads, climbing grades and long-distance towing. For GM, the 8.3-litre Duramax is aimed directly at those demanding use cases.
The New Duramax Is Far More Than a Power Increase
The outgoing 6.6-litre Duramax became a familiar part of Chevrolet and GMC heavy-duty pickups, producing 470 horsepower and 975 lb-ft of torque in its latest form. The new 8.3-litre engine raises those numbers to 555 horsepower and 1,230 lb-ft. That represents gains of 85 horsepower and 255 lb-ft of torque, enough to push GM ahead of the current diesel-output figures offered by its Detroit rivals.
More importantly, GM describes this as its first clean-sheet heavy-duty diesel V8 designed, developed and manufactured entirely in-house for pickup applications. In other words, engineers were not simply increasing boost pressure or enlarging an existing engine. Major systems ranging from the rotating assembly and combustion design to cooling and emissions aftertreatment were developed around the new architecture. GM had teased the engine under the internal “Mongoose” name before releasing the specifications. The result is one of the largest-displacement diesel engines currently offered in a mainstream North American pickup.
The Hardware Was Designed Around Working Under Load
The 8.3-litre Duramax uses a compacted graphite iron cylinder block combined with a fully forged crankshaft, forged connecting rods and steel pistons. Those components matter because a heavy-duty diesel can spend long periods working under substantial cylinder pressure and heat. GM also fitted high-flow fuel injection and a high-efficiency variable-geometry turbocharger rather than designing the engine simply to deliver an impressive short burst of peak output.
Cooling received similar attention. GM specifies a compact dual-stage air-to-water charge-cooling system and an upgraded engine-cooling strategy intended to maintain performance during demanding towing. An integrated intake, revised combustion system and crankshaft-isolation hardware are intended to reduce vibration and noise. The engine is paired with an Allison-branded 10-speed automatic transmission, upgraded exhaust braking and a redesigned aftertreatment arrangement. Taken together, those changes indicate that GM’s focus is sustained heavy-duty performance rather than horsepower alone — an important distinction for a truck climbing a long grade with a large trailer attached.
Towing Climbs to 38,000 Pounds, but Configuration Still Matters
GM says properly equipped 2027 Silverado HD and Sierra HD models can tow as much as 38,000 pounds with a gooseneck setup. Maximum conventional towing reaches 20,000 pounds, while maximum gross combined weight rating rises to 46,500 pounds on select configurations. GM also says every diesel-powered dual-rear-wheel model can be configured for at least 30,000 pounds of available towing capability.
Those numbers require context because a truck’s maximum rating never applies universally across the lineup. Cab style, drivetrain, axle configuration, equipment, passengers and cargo can all change what a particular truck is legally and mechanically rated to carry. Chevrolet Canada’s specifications illustrate the distinction: the diesel Silverado HD is listed with maximum available payload of 6,170 pounds, while the enhanced gasoline version reaches 6,990 pounds in its optimal configuration. Buyers pulling large fifth-wheel or gooseneck trailers therefore still need to consider payload and pin or tongue weight, not just the largest towing number printed in a brochure.
GM Has Also Rethought How Its Heavy-Duty Trucks Steer and Stop
One of the most significant 2027 changes is hidden behind the huge engine figures. GM is replacing the traditional hydraulic-assisted steering arrangement with rack-and-pinion electric power steering, which the company describes as a segment first for heavy-duty pickups. GM says the system can provide roughly 30% more steering output than the outgoing hydraulic setup while improving on-centre precision, reducing kickback and eliminating hydraulic pumps, hoses, fluid and related components.
Braking receives its own major update. The trucks introduce an electronic brake-boost system, accompanied by larger front brakes and four-piston front calipers. GM says the hardware is designed to deliver more predictable braking performance under demanding conditions. Tow/Haul and Off-Road modes now coordinate more of the truck’s powertrain, steering and braking behaviour rather than adjusting the transmission alone. Silverado HD ZR2 and Sierra HD AT4X models additionally receive Terrain Mode, which can provide one-pedal-style control during low-speed off-road driving in four-wheel-drive settings.
GM Wins the Output Battle, but Not Every Capability Contest
The new Duramax arrives squarely in a heavy-duty power race. Ford’s current high-output 6.7-litre Power Stroke diesel is rated at 500 horsepower and 1,200 lb-ft of torque. Ram’s high-output 6.7-litre Cummins inline-six produces 430 horsepower and 1,075 lb-ft. Against those currently published figures, GM’s 555 horsepower and 1,230 lb-ft give the 8.3-litre Duramax the highest advertised diesel horsepower and torque of the three.
That does not mean the Chevrolet or GMC automatically leads every specification. Ford’s 2026 Super Duty can be configured for up to 40,000 pounds of gooseneck towing, compared with GM’s newly announced 38,000-pound maximum. Ram lists up to 36,610 pounds for its 2026 3500 diesel. These comparisons also cross model years because GM’s figures apply to its incoming 2027 trucks while the currently published rival numbers are for 2026 models. The broader lesson is that horsepower, torque, payload and towing leadership can belong to different trucks depending on the configuration and measurement being compared.
Canada Has a Larger Role in the Truck Program Than the Sales Numbers Suggest
The Canadian connection extends beyond the nearly 65% diesel take rate. Chevrolet’s Canadian website says select Silverado HD models are assembled at GM’s Oshawa plant for Canadian and U.S. distribution. Oshawa passed 500,000 Silverado pickups built since production resumed in 2021, and GM has committed hundreds of millions of dollars to prepare the facility for another generation of gas-powered full-size pickups.
GM has also confirmed that Oshawa is expected to eventually build both next-generation Chevrolet Silverado HD and GMC Sierra HD trucks, although the timing of that future production has not been specified. That distinction matters because it does not mean every 2027 Sierra HD will suddenly be Oshawa-built. Canadian engineering plays a role as well. Reporting on the 2027 program says GM’s Canadian Technical Centre contributed to trailering systems and integrated controls, building on years of Canadian development work involving technologies such as Transparent Trailer View. The Canadian Technical Centre now employs more than 1,000 engineers, developers and technical specialists.
Buyers Still Have a Gas Option — and Some Canadian Details Need Clarification
Diesel will remain optional rather than mandatory. GM’s enhanced 6.6-litre gasoline V8 is rated at 412 horsepower and 472 lb-ft of torque and is also paired with the Allison 10-speed automatic. Chevrolet Canada lists maximum available gasoline towing at 19,000 pounds and payload at 6,990 pounds. For owners who do not regularly tow extremely heavy loads, the gas engine could remain an important alternative without the added complexity and cost associated with a modern diesel powertrain.
Several launch details are still developing. Chevrolet Canada says the 2027 Silverado HD is anticipated later in 2026, while Canadian pricing has not yet been announced. There is also a specification inconsistency worth watching: Chevrolet Canada currently lists the Duramax at 555 horsepower, matching GM’s corporate announcement, while GMC Canada’s 2027 Sierra HD page lists 550 horsepower. Both list a 38,000-pound maximum towing figure. GM has not published an explanation establishing that the Sierra uses a different calibration, so the five-horsepower difference should be treated as an unresolved discrepancy rather than evidence of a confirmed mechanical difference.
