GM's New 8.3L Duramax Has a Name: Mongoose — and a Target: Ford
The teaser confirms years of rumors — and openly mocks the "Scorpion" codename of Ford's 6.7-liter Power Stroke. Specs are still under wraps. Tags: GM, Chevrolet Silverado HD, GMC Sierra HD, Duramax, diesel, pickup truck
General Motors has confirmed one of the longest-running rumors in the truck world: an all-new 8.3-liter Duramax turbo-diesel V8, named Mongoose, will power the refreshed 2027 Chevrolet Silverado HD and GMC Sierra HD. The 40-second teaser GM released Monday doesn't include a single spec — but it does include a very deliberate insult aimed at Ford.
Scorpion has long been the development codename for Ford's 6.7-liter Power Stroke diesel, the engine that powers the F-Series Super Duty. GM's clip stages a desert standoff between the two animals, and the mongoose — with Chevy bow ties flashing in its eyes — wins. The company's announcement spells it out, noting that nature, "or GM in this case, always engineers a better predator."
Beyond the name, the displacement, and the two trucks that will carry it, GM confirmed nothing. There are no horsepower, torque, towing, or payload figures yet. Chevrolet and GMC say more information is coming soon.
The numbers GM didn't publish are the whole story here. The current 6.6-liter Duramax makes 470 hp and 975 lb-ft of torque and tows up to 36,000 pounds through a 10-speed Allison automatic. That torque figure trails both rivals: Ram's 6.7-liter Cummins produces 430 hp and 1,075 lb-ft, while Ford's High-Output Power Stroke leads the segment at 500 hp and 1,200 lb-ft. A new engine with roughly 26 percent more displacement only makes sense if GM intends to take that crown — you don't tease a mongoose hunting a scorpion to announce second place.
The jump in size is historic for the brand. Every Duramax offered in GM's pickups has displaced 6.6 liters since the engine line debuted in the early 2000s, which makes the 8.3 the largest diesel ever fitted to a Silverado or Sierra.
Some unofficial details have already surfaced. According to order guides seen by GM Authority, the new diesel carries the RPO code L6P — replacing the current engine's L5P designation — and pairs with an Allison-branded 10-speed automatic. GM hasn't confirmed either detail.
The Mongoose arrives as part of a broader refresh of both HD trucks for the 2027 model year; Motor1 reports the updated pickups could debut before the end of the year. Full specifications — and, presumably, a response from Dearborn — should follow.
