Chevrolet Silverado HD / GMC Sierra HD Duramax "Mongoose"

GM Gives Its Next Diesel a Fighting Name

The 2027 Chevrolet Silverado HD and GMC Sierra HD will introduce a new 8.3-liter Duramax turbo-diesel V8 called Mongoose. The name is a pointed bit of rivalry: Ford's 6.7-liter Power Stroke carries the internal codename Scorpion. GM's teaser even tells a mongoose-and-scorpion story, making clear which heavy-duty competitor it has in sight.

A Bigger V8 Replaces the 6.6-Liter Duramax

Mongoose will replace GM's current 6.6-liter diesel, which makes 470 horsepower and 975 pound-feet of torque. GM has not published output, towing, payload, or efficiency figures for the 8.3-liter engine yet. Ford currently reaches 500 horsepower and 1,200 pound-feet with its high-output Power Stroke, while Ram's Cummins diesel produces 430 horsepower and 1,075 pound-feet. Those numbers establish the targets, not the new Duramax's final rating.

New Engine, Refreshed Heavy-Duty Trucks

The Silverado HD and Sierra HD are also expected to receive updated styling for 2027, with cues from their refreshed light-duty siblings. A debut could happen before the end of 2026, though GM has not provided a date. For truck buyers, the real reveal will be less about the Mongoose badge than what the larger displacement does for sustained towing, cooling, and torque under load.