General Motors is preparing a significant powertrain update for its heavy-duty Silverado and Sierra pickup trucks ahead of their next full redesign. According to reports citing sources within GM, the company will introduce new V8 gasoline and diesel engines starting with the 2027 model year, giving current-generation truck owners more power and capability before the all-new generation arrives in 2029.

New Engines Coming to Heavy-Duty Silverados

The 2027 Silverado HD will receive two upgraded powertrains. The first is a new naturally aspirated 6.6-liter V8 gasoline engine designated the L8S, which replaces the current L8T. While displacement remains the same, the new L8S is expected to deliver more horsepower and torque than the existing engine, which currently produces 401 horsepower and 464 pound-feet of torque. This upgrade should appeal to buyers seeking increased towing and hauling capability.

The diesel option gets even more attention. GM will introduce the next-generation Duramax diesel engine, the L6P, replacing the current L5P. The existing diesel delivers 470 horsepower and 975 pound-feet of torque, making it one of the most powerful diesel options in the truck market. Details about the new L6P’s output remain limited, but industry expectations suggest GM will maintain or increase the torque figure that diesel truck buyers depend on.

Why This Timing Makes Sense for Shoppers

truck engine power shot
Photo by Michael SKOPAL

One might wonder why GM would introduce new engines now rather than waiting for the complete truck redesign in 2029. The automaker has invested billions in powertrain development in recent years, and holding these advances back for two additional years would waste that engineering investment and delay customer access to improved technology. By launching the L8S and L6P in 2027, GM capitalizes on its research spending while keeping the current truck lineup competitive.

For potential buyers, this creates an interesting window. Those shopping for heavy-duty Silverados in the next two years face a choice: purchase the current generation now, or wait for 2027 when more powerful engines become available. Limited edition Silverado models have already launched with enhanced specifications, signaling that GM is actively refreshing its truck lineup.

The Bigger Picture for GM and the Truck Market

diesel truck towing capacity
Photo by ALEXANDRE DINAUT

GM’s commitment to developing new internal combustion engines might seem counterintuitive given the industry’s push toward electrification. However, the company recently announced a $920 million investment to support Duramax diesel production in Ohio, demonstrating a serious long-term commitment to combustion engine technology. This reflects market reality: despite EV enthusiasm, truck buyers continue choosing gasoline and diesel powertrains, and demand shows no signs of declining anytime soon.

The automaker recently redesigned its light-duty Silverado 1500 and Sierra 1500 with updated engines, and many buyers have customized these trucks with aftermarket exhaust systems and performance upgrades. That same refresh cycle is now coming to the heavy-duty segment, making 2027 a milestone year for the brand’s truck portfolio.

What Buyers Should Consider

If you’re in the market for a heavy-duty truck, understanding this timeline helps inform your decision. Current 2024 and 2025 model year Silverado HDs offer proven powertrains with established reliability and real-world performance data. Waiting until 2027 provides access to newer technology and potentially better fuel efficiency, but means delaying your purchase and potentially paying more as a result of the fresh engineering.

Diesel buyers deserve special attention. The Duramax has earned a strong reputation for durability and torque output, crucial for serious commercial and towing applications. The new L6P engine will likely carry forward that tradition while potentially offering improved efficiency or additional power. Safety considerations like headlight performance also matter when choosing any truck model.

GM’s investment in these powertrains signals the company’s confidence in the truck market and its commitment to keeping internal combustion engines competitive. Whether you need maximum power now or can wait for the next generation, the news that stronger engines are coming soon validates the heavy-duty truck segment as a priority for American automakers.