General Motors has released detailed specifications for two sixth-generation small-block V8 engines that will help power the next-generation 2027 Chevrolet Silverado 1500 and GMC Sierra 1500.
The new engine family includes the L76 5.7L V8, producing 402 horsepower and 428 lb.-ft. of torque, and the L78 6.6L V8, rated at 481 horsepower and 501 lb.-ft.
GM describes the 6.6L as the most powerful naturally aspirated V8 in its segment. Both engines will be paired with a 10-speed automatic transmission.
The powertrains expand upon the preliminary information released with the redesigned 2027 Chevrolet Silverado 1500 and 2027 GMC Sierra 1500.
Two New Small-Block V8 Engines
The L76 and L78 replace the previous 5.3L and 6.2L V8 configurations with larger 5.7L and 6.6L displacements.
GM increased the piston stroke by 6 millimeters, returning the familiar 350- and 400-cubic-inch displacements to the small-block engine family. The engines retain the 4.40-inch cylinder-bore spacing that has been part of GM’s small-block architecture since its introduction in 1955.
Key specifications include:
| Engine | Horsepower | Torque |
|---|---|---|
| L76 5.7L V8 | 402 hp | 428 lb.-ft. |
| L78 6.6L V8 | 481 hp | 501 lb.-ft. |
Although the engines share a common architecture, their published towing and payload ratings reflect different truck configurations and intended applications.
The 5.7L V8 supports a maximum available towing rating of 13,700 pounds in the Silverado and 13,500 pounds in the Sierra when properly equipped. The 6.6L V8 emphasizes higher horsepower and torque, with published maximum towing ratings of 9,700 pounds for the Silverado and 9,400 pounds for the Sierra.
Actual capability will depend on cab, bed, drivetrain, axle, trim and equipment configuration.
New Fuel and Lubrication Technology
The sixth-generation V8s introduce a dual-fuel delivery system combining direct injection with port fuel injection. The system allows the engine controller to select or combine injection methods based on power, efficiency and emissions requirements.
Other changes include:
- Higher compression ratios
- Larger throttle diameters
- New intake manifolds with tuned runners
- A continuously variable oil pump
- An engine-mounted oil cooler
- Revised oil passages designed to provide more consistent pressure
These changes are intended to improve airflow, combustion control, lubrication and thermal management during towing, hauling, commuting and off-road operation.
GM expects its development teams to complete more than 1.5 million miles of real-world road validation before the next-generation trucks reach dealerships.
Four Engines for Different Fleet Applications
The two V8s will join an enhanced TurboMax gasoline engine and the available 3.0L Duramax Turbo-Diesel. All four engines will use a 10-speed automatic transmission.
| Engine | Horsepower | Torque | Maximum Available Towing |
| Enhanced TurboMax | 350 hp | 455 lb.-ft. | 9,400 lbs. |
| Duramax 3.0L Turbo-Diesel | 305 hp | 495 lb.-ft. | 12,100 lbs. |
| L76 5.7L V8 | 402 hp | 428 lb.-ft. | 13,700 lbs. |
| L78 6.6L V8 | 481 hp | 501 lb.-ft. | 9,700 lbs. |
The highest ratings shown represent the best-performing Silverado or Sierra configuration for each engine. Ratings vary by model and equipment.
For commercial fleets, the expanded lineup provides several ways to match the powertrain to the vehicle’s duty cycle. The TurboMax offers the highest published maximum payload, while the Duramax emphasizes low-end torque and highway range. The 5.7L V8 carries the highest published towing rating, and the 6.6L V8 provides the lineup’s highest horsepower and torque.
A new 34-gallon fuel tank will be available with the V8 engines and Duramax diesel. GM estimates that the Duramax can exceed 900 miles of highway range when paired with the larger tank in the applicable two-wheel-drive configuration.
North American Engine Production
Initial production of the 5.7L and 6.6L V8 engines will take place at GM’s Flint Engine Operations in Michigan. Additional production capacity is planned for Tonawanda Propulsion in New York and St. Catharines Propulsion in Ontario.
GM previously announced $888 million in investment at Tonawanda for sixth-generation V8 production. The automaker is also investing C$691 million at St. Catharines to support the new engine family.
The investments are part of GM’s broader North American manufacturing strategy for its next-generation pickups, engines and transmissions.
What Fleet Buyers Should Consider
Fleet buyers should avoid choosing an engine solely by its peak horsepower rating. Vehicle configuration, payload, trailering requirements, annual mileage, idling patterns, fuel availability and acquisition cost can all affect which powertrain delivers the best operational value.
The 5.7L V8’s maximum available towing rating may appeal to fleets regularly pulling heavier trailers. The 6.6L V8 may be better suited to buyers prioritizing acceleration, off-road performance or higher output in specific configurations. High-mileage operators may continue to favor the Duramax diesel, while fleets carrying heavier cargo without large trailers may find the TurboMax’s payload capability attractive.
The new engines will become available when the next-generation Silverado 1500 and Sierra 1500 reach dealerships later in 2026. Pricing and complete configuration details will vary by model and will be announced separately.
Source: General Motors, September 17, 2026.
