General Motors has announced updates to its 2027 heavy-duty truck lineup, which will launch across the Chevrolet Silverado HD and GMC Sierra HD. The updates include a new in-house-designed heavy-duty diesel engine, rack-and-pinion electric power steering and a new electronic brake-boost architecture.
The technologies are designed to improve power, control and refinement when towing, hauling and driving off-road.
“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,” said Mark Dickens, executive chief engineer for GM full-size trucks and SUVs. “HD customers don’t hold back – and neither did we.”
New heavy‑duty diesel & enhanced gas engine
The new diesel is GM’s first clean-sheet heavy-duty V8 designed, developed and manufactured in-house specifically for heavy-duty pickup applications. It uses a compacted graphite iron cylinder block, fully forged crankshaft and connecting rods, and steel pistons.
GM says the engine will deliver best-in-class diesel horsepower and torque, with a broad torque curve, high-flow fuel injection and vehicle-level integration for towing and other heavy-duty applications.
The cooling and turbocharging systems include a dual-stage air-to-water charge-cooling system, a variable-geometry turbocharger and an updated engine-cooling strategy. These are designed to maintain performance during sustained loads.
GM has also revised the engine architecture, intake, combustion system and crankshaft isolation hardware to reduce noise and vibration.
The diesel powertrain is paired with an Allison 10-speed transmission, upgraded exhaust braking and a revised aftertreatment layout. These systems support towing, engine braking and emissions control during heavy-duty use.
“This new diesel engine is the culmination of decades of GM diesel development and integration,” said Norman Peralta, executive chief engineer, global engine and battery systems. “From the clean-sheet architecture and combustion system to the cooling, aftertreatment and transmission calibration, this is a powertrain built with heavy-duty purpose and pride.” The new engine will be built at GM’s expanded DMAX facility in Brookville, Ohio.
The standard 6.6-liter gas V8, assembled at GM’s Tonawanda Propulsion Plant in New York, also gains horsepower and torque. Updates include a new Turbo-Jet intake manifold, revised lubrication system, engine-mounted oil cooler, updated emissions hardware and a digital oil-level display.
Both the new diesel and updated 6.6-liter gas V8 are paired with the Allison 10-speed 10L1000 transmission and revised shift logic. The calibration is intended to keep the engines within their operating range during acceleration, gradients and heavy towing.
The 2027 HD models are engineered to offer towing capability of up to 21,090kg GCWR and up to 17,237kg max trailering on select configurations.
Other core updates
GM’s HD pickups will use a new rack-and-pinion electric power steering system for 2027. Described by GM as a ‘segment first for heavy-duty trucks’, it replaces the previous hydraulic-assisted system with an electric architecture developed for heavy-duty applications.
The pickups will also feature an updated braking system, including larger 370mm front rotors, new four-piston fixed front calipers and upgraded rear hardware. The changes increase brake thermal capacity and pedal stiffness, particularly during heavy towing.
Available visibility technology for easier towing – including up to 14 camera views such as Transparent Trailer View, Bed View and Surround Vision to help with hitching, lane changes, reversing and trailer monitoring – are also added.
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