General Motors has officially confirmed an all-new 8.3-litre Duramax turbodiesel V8 that will power the refreshed 2027 Chevrolet Silverado HD and GMC Sierra HD pickups. The engine carries the internal nickname Mongoose, a deliberate and unusually direct swipe at Ford, whose 6.7-litre Power Stroke diesel V8 has long been known internally as Scorpion.
The name is not incidental branding. GM's teaser material shows a mongoose hunting a scorpion, and the company describes the new engine as «built to dominate», casting the mongoose as the better predator. The message to Ford is unmistakable, and it signals that the heavy-duty diesel horsepower race is far from over.
Beyond displacement and cylinder count, GM is keeping most technical details under wraps. Horsepower, torque, towing capacity, transmission specifications and pricing have not been released. The company has also not said whether the 8.3-litre unit will replace the current 6.6-litre Duramax outright or serve as a higher-output option, nor which Silverado HD and Sierra HD configurations will receive it. Those details are expected later.
The existing 6.6-litre Duramax produces 470 hp and 975 lb-ft of torque. Ford's high-output 6.7-litre Power Stroke currently leads the segment with 500 hp and 1,200 lb-ft, while Ram's latest 6.7-litre Cummins delivers 430 hp and 1,075 lb-ft. The jump from 6.6 to 8.3 litres represents a 26 per cent increase in displacement, giving GM an obvious target to beat.
Displacement alone does not guarantee class-leading output, but having released a promotional video about mongooses eating scorpions, GM would look foolish if the new engine could not at least make Ford sweat. The confirmation also lands in a competitive period for heavy-duty trucks, where towing and payload figures are closely watched by buyers who use these vehicles for work as much as for transport.
For now, the target is clear and GM appears confident it is about to outduel Ford in the segment. The refreshed 2027 Silverado HD and Sierra HD will be the first models to benefit, with full specifications expected closer to launch.