The heavy-duty horsepower and torque war shows no sign of slowing as we head into 2027. General Motors just announced a new 8.3-liter Duramax diesel engine with class-leading output numbers, and it’s a shot directly at Ford’s heavy-duty Power Stroke diesel.
GM’s new diesel V8 produces 555 horsepower and 1,230 lb-ft of torque, besting the 2027 Ford Super Duty’s 6.7-liter engine, which makes 500 hp and 1,200 lb-ft of torque in its most powerful format.
That output enables conventional towing of up to 20,000 pounds and gooseneck towing of up to 38,000 pounds with the right equipment, the latter figure now matching the max a Ford F-350 can pull. The engine features a compacted graphite iron cylinder block and a fully forged crankshaft. GM also noted a new high-flow fuel injection system that improves takeoff speeds with heavy trailers and helps with towing up steep grades.
Other upgrades over the previous diesel include a dual-stage air-to-water charge cooling system and a variable-geometry turbocharger. The automaker says that the new engine architecture helps reduce noise and vibration, two hallmarks of powerful diesel trucks.
While the Duramax name is nothing new, the 8.3-liter engine is GM’s first in-house-designed HD diesel engine, and the automaker seems confident that it’s a proven performer. GM’s executive chief engineer for full-size trucks, Mark Dickens, said, “For 2027, we took GM’s proven HD validation playbook and turned up the capability — integrating new powertrain, braking, steering, and chassis technologies for serious customers who push their trucks hard every day. HD customers don’t hold back — and neither did we.”
More than 60% of GM’s heavy-duty truck buyers opt for the diesel engine, making this new power plant a big story for 2027. The base gas engine wasn’t forgotten, however, as it now offers best-in-class torque, at 472 lb-ft. Both gas and diesel engines pair with an Alison 10-speed automatic transmission.
The 2027 Chevrolet Silverado HD and GMC Sierra HD with GM’s fresh Duramax diesel engine will begin arriving at U.S. dealers late in 2027.
