General Motors has introduced major mechanical upgrades to its heavy-duty pickup trucks, the Chevrolet Silverado HD and GMC Sierra HD, for the 2027 model year. The 2027 Silverado HD and Sierra HD bring a new 8.3-liter Duramax diesel V-8, higher towing capacity, electric rack-and-pinion steering and an updated braking system.
The biggest news for both trucks is the new 8.3-liter Duramax turbo-diesel V8, completely redeveloped by GM. This engine produces 555 hp and 1,230 lb-ft of torque and will be available in both trucks.
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In addition to the new engine, the 2027 Silverado HD and Sierra HD also feature significant changes to the steering and braking systems. For the first time, GM has introduced rack-and-pinion electric power steering in its HD pickups, while a new electronic brake-boost system has been used for braking.
According to the company, the new steering system provides approximately 30 percent more output than the old hydraulic setup.
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The 8.3L Duramax V8 will deliver 555 HP and 1,230 lb-ft of Torque
The biggest mechanical highlight of the 2027 Chevrolet Silverado HD and GMC Sierra HD is the new 8.3L Duramax diesel engine. GM claims it’s its first all-new, in-house-designed heavy-duty diesel V8.
This engine produces 555 horsepower and 1,230 lb-ft of torque. For comparison, the current 6.6L Duramax diesel produces 470 hp and 975 lb-ft of torque. With the new engine, GM has delivered a significant jump in displacement as well as torque output.
The engine is paired with an Allison 10-speed 10L1000 automatic transmission. It also features updated shift logic to keep the engine in its more useful operating range during towing.
6.6L Gas V8 Also Updated
For buyers who don’t want a diesel, GM has also updated the 6.6-liter gasoline V8. It now generates 412 hp and 472 lb-ft of torque.
GM has made updates to the engine, including a new intake manifold, a revised lubrication system, and improved cooling-related hardware. This engine also comes with an Allison 10-speed automatic transmission.
Towing Capacity Increased to 38,000 Pounds
The engine upgrades in heavy-duty trucks have also directly benefited towing capability. Properly equipped 2027 Silverado HD and Sierra HD can now tow up to 20,000 pounds conventionally and up to 38,000 pounds gooseneck towing.
According to GM, diesel-powered dual-rear-wheel configurations will offer at least 30,000 pounds of towing capability. However, the actual towing capacity will depend on the truck’s configuration, cab, drivetrain and equipment.
Electric Rack-and-Pinion Steering for the First Time
Mechanical changes in the 2027 HD trucks aren’t limited to the engine. GM has replaced the old hydraulic-assisted steering setup with electric power-assisted rack-and-pinion steering.
GM says this system provides approximately 30 percent more steering output. Furthermore, the steering assist can be tuned for different drive modes. The company claims this will help improve on-center feel and reduce steering kickback on rough surfaces.
This is a major technical change in the heavy-duty pickup segment, as hydraulic steering systems have long been used in this category.
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Electronic Brake-Boost and Bigger Brakes
Along with the steering, the braking system has also been changed. The new Silverado HD and Sierra HD feature an electronic brake-boost system.
It comes with 14.6-inch brake rotors and four-piston calipers in the front. GM says the new setup is designed to provide better heat management and a more consistent braking feel. The electronic architecture can also be more closely integrated with active safety systems.
In off-road-focused versions, GM has also added a new Terrain Mode, which enables one-pedal off-road control in 4HI or 4LO.
2027 Silverado HD and Sierra HD Pricing
GM has not yet announced pricing for the 2027 Chevrolet Silverado HD and GMC Sierra HD. According to the company, both trucks will begin arriving at U.S. dealerships in late 2026. Pricing and additional product details will be released closer to launch.
Auto India Daily Verdict
In the 2027 Silverado HD and Sierra HD, GM has not only added a larger diesel engine, but has also updated the powertrain, steering, braking, and towing systems.
The new 8.3L Duramax V8 and 1,230 lb-ft of torque are the biggest headlines of this update, while electric steering and electronic braking could bring major technical changes to the driving experience.
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Raj Prajapati is a Senior Automotive Content Writer at AutoIndiaDaily. A B.Tech graduate in Computer Science and Engineering, he leverages over four years of experience covering Indian car and bike launches, EV tech, and market dynamics to break down complex automotive regulations into simple consumer guides. Specialising in Indian motor vehicle laws, IRDAI updates, and ownership costs, Raj translates technical auto policies into actionable advice for everyday drivers.