GM teases 8.3-liter Duramax diesel engine for 2027 HD trucksQuartzCris TolomiaUpdatedTue, September 22, 2026 at 12:19 PM UTCAdd us on GoogleGM is challenging Ford's heavy-duty diesel dominance with a bigger engine hero imageGeneral Motors teased a new 8.3-liter Duramax V8 turbo-diesel engine on Monday, confirming the powertrain will appear in the refreshed 2027 Chevrolet Silverado HD and GMC Sierra HD. GM is calling it the Mongoose.The announcement includes no output figures. The engine is set to succeed GM's outgoing 6.6-liter Duramax V8, rated at 470 horsepower and 975 pound-feet of torque. The 8.3-liter displacement would mark the first time a Duramax engine in a pickup truck has exceeded 6.6 liters, a size GM has used since 2000, according to The Drive.The Mongoose name is a direct dig at Ford's 6.7-liter Power Stroke diesel, whose internal development codename is "Scorpion." GM's teaser shows a mongoose fighting a scorpion. Ford's Power Stroke currently produces 500 hp and 1,200 lb-ft of torque. Ram's rival offering, a 6.7-liter Cummins inline-six diesel, is rated at 430 hp and 1,075 lb-ft of torque.AdvertisementAdvertisementGM has yet to clarify whether the 8.3-liter will slot in beside the 6.6-liter or phase it out completely, according to The Drive. The 2027 Silverado HD and GMC Sierra HD could debut before the end of the year, according to Motor1. Beyond the powertrain upgrade, the refreshed heavy-duty trucks are also anticipated to carry over design cues established by the 2027 Silverado 1500 and GMC Sierra 1500.GM's heavy-duty truck push comes as the company faces pressure in the broader pickup segment. GM reported that Silverado sales fell 7.7% in the second quarter, contributing to an overall U.S. sales decline of 4.2% for the period. The GMC Sierra was a relative bright spot, with sales climbing 5% in the quarter. GM said it still expects to have gained market share in the full-size truck segment during that period.
