The Big Trucks Join In
The Chevrolet Silverado HD and GMC Sierra HD may not get a full redesign like their smaller light-duty counterparts for the 2027 model year, but they are still expected to receive some updates. These could include powertrain changes, with new gasoline and diesel engines on the way.
GM Authority, citing sources familiar with the matter, reported that the two heavy-duty trucks will offer new engines designated L8S and L6P. The former is essentially an updated version of the current 6.6-liter L8T naturally aspirated gasoline V8, while the latter would replace the current 6.6-liter L5P Duramax turbodiesel V8.
GMC
Bigger Might Be Better
The publication did not disclose output figures, though it said the L8S will retain the same 6.6-liter displacement, while the L6P could get a displacement increase. A larger displacement could help boost performance over the L5P, which currently delivers 470 horsepower and 975 lb-ft of torque. That could make it more appealing, at least on paper, especially against heavy-duty rivals from Ram and Ford, whose available Cummins and Power Stroke diesel engines exceed 1,000 lb-ft of torque.
The current L8T gas V8 makes 401 horsepower and 464 lb-ft of torque. Both engines come with a 10-speed automatic transmission, with gas models dropping their 6-speed auto for the 2024 model year.
Again, General Motors has not confirmed these powertrain updates, so take them with a grain of salt. Order books for the 2027 Silverado HD will reportedly open on September 17, so new details should emerge sooner rather than later. Production is reportedly scheduled to begin this November.
Chevrolet
A Fresh Start Under the Hood
What’s confirmed are the new engines coming to the light-duty Chevy Silverado and GMC Sierra. These include an updated TurboMax and two new Gen 6 small-block V8s replacing the 5.3-liter L84 and 6.2-liter L87. The latter has been at the center of a recall and proposed class-action litigation over connecting rod, crankshaft, and bearing failures.
Meanwhile, the 3.0-liter Duramax inline-six turbodiesel is expected to be largely carried over, reportedly retaining its current outputs of 305 horsepower and 495 lb-ft of torque. Comprehensive specifications for the 2027 Silverado 1500 are reportedly due on September 17.
GMC
