GM’s 8.3L Duramax “Mongoose” Targets Ford’s Power Stroke: What We KnowThe Auto WireEve NowellWed, September 23, 2026 at 2:10 PM UTCAdd us on Google1 / 2GM’s 8.3L Duramax “Mongoose” Targets Ford’s Power Stroke: What We KnowGM has spent years watching Ford make the biggest torque number in the heavy-duty pickup segment. Its answer is more displacement. GM has teased an all-new Duramax 8.3L Turbo-Diesel V8, which it says will power the refreshed 2027 Chevy Silverado HD and GMC Sierra HD. Its code name is Mongoose, and GM does not pretend the name is anything other than a shot at a rival. General MotorsGM's official teaser release mentions a "cross-town rival" whose diesel "may be referred to as the 'scorpion'." That isn't a guess from fans. A Ford technical paper filed with SAE in 2010 names the 6.7L Power Stroke V-8 and says it was code named "Scorpion" during development at Ford. Mongooses are famous for killing venomous prey, and GM chose the animal accordingly. GM also filed the release's lead image under a name ending in "MvS," which reads a lot like Mongoose vs. Scorpion. SAEWhat GM Actually ConfirmedThe confirmed facts are few: the displacement, the cylinder layout, turbocharging, diesel fuel, and the two trucks that will get it. The release has no horsepower, torque, towing, payload, pricing, or on-sale date. GM calls the release a first look and says Chevy and GMC will share more soon. You can watch the teaser video yourself. It's mostly desert wildlife and attitude, with no spec sheet. General MotorsRelated ArticlesThe Motorcycle Industry Just Found a $3.3 Billion Business That Isn't Selling MotorcyclesVolvo Crammed an EV-Sized Battery Into the XC60 Plug-In Hybrid — Brussels Did the Math FirstAdvertisementAdvertisementFor now, anything beyond displacement is guesswork, and GM has published no numbers to judge it by.The Numbers the Mongoose Has to BeatHere is the scoreboard as the manufacturers publish it today. Ford says its 6.7L High Output Power Stroke makes 500 hp and 1,200 lb-ft of torque. Chevrolet rates the current Duramax 6.6L Turbo-Diesel V8 at 470 horsepower and 975 lb-ft. Stellantis lists the Cummins HO 6.7-liter inline-six at 430 hp and 1,075 lb-ft, paired with an eight-speed automatic. 2026 Ford Super Duty® Truck | Pricing, Photos, Specs & More | Ford.comThat leaves GM 225 lb-ft behind Ford in a segment where torque figures sell trucks. The Silverado HD is last in the torque ranking, and the Mongoose's job is to change that.Why More Displacement Instead of More BoostThe math explains why GM went bigger instead of turning up the current engine.AdvertisementAdvertisementMeasured as torque per liter, Ford's 6.7 makes about 179 lb-ft per liter. The Cummins makes about 160. GM's 6.6 makes about 148. The Duramax has been making less torque from each liter than either rival.Now put the current Duramax's torque-per-liter into 8.3 liters. That works out to roughly 1,226 lb-ft, which would edge past Ford without asking any more of each liter than the L5P does today. If GM matched Ford's torque-per-liter, it would be near 1,490 lb-ft. Neither figure is a prediction. They show why engineers like displacement: a bigger engine reaches a torque target while each cylinder works less hard.In practice, lower pressure in each cylinder for the same output generally means less stress on head gaskets, pistons, and bearings, and less heat. Heat is the enemy of any diesel that spends its life towing a 15,000-pound fifth wheel up a mountain grade. A larger engine can also reach its torque at lower rpm, which helps fuel economy on the highway while towing.There's another detail worth noticing. Split 8.3 liters across eight cylinders and you get about 1.04 liters per cylinder. That's much bigger than the current Duramax at 0.825 and Ford's V8 at about 0.84. It's still smaller than the Cummins inline-six at about 1.12 liters per cylinder. Ram fans can keep their bragging rights, at least on that one measure.AdvertisementAdvertisementAnd in a segment known for big gas engines, the Mongoose will out-displace every one of them. Ford's largest Super Duty gas engine is a 7.3L V8 making 430 hp and 485 lb-ft. FordThe Emissions Question Nobody Is Answering YetLaunching an all-new diesel for the 2027 model year matters for regulatory reasons too. The EPA's 2024 multi-pollutant rule set new criteria pollutant and greenhouse gas standards for Class 2b and 3 "medium-duty" vehicles, phasing in over model years 2027 through 2032. The EPA's program announcement says that category mainly covers large pickups and vans with a GVWR between 8,501 and 14,000 pounds. That describes a Silverado 2500HD and 3500HD. govinfoepaWhatever the rule's current status, a new engine is the natural point to design in emissions hardware and certification strategy, rather than adding them to an old block. GM hasn't said anything about aftertreatment, DEF consumption, or regeneration behavior. Anyone who tows for a living should ask about those things before asking about horsepower.What Owners and Buyers Should KnowFirst-year risk is real. Every generation of modern diesel has had early issues, whether fuel systems, injectors, or cooling. A clean-sheet engine in its first model year has no track record for independent shops to work from. Buyers who need a truck that works every day may want to let a year of fleet miles build up first.Related ArticlesWatch: A GT-R Ran From a Georgia Trooper at 170 MPH. Federal Tire Rules Stop Testing at 99.Toyota Found a Power-Loss Bug in 21,000 EVs by Accident — While Testing a Totally Different CarAdvertisementAdvertisementRepair and insurance costs are unknown. Insurers and extended-warranty companies price risk using repair history, and there is none yet. Expect conservative pricing on service contracts until real claims data exists. Parts for a brand-new engine family will also be dealer-only for a while.Don't count on the 6.6 disappearing right away. GM hasn't said whether the 8.3 replaces the current Duramax or sits above it. If a 6.6 remains in the 2027 lineup, it may become a strong value pick among outgoing or carryover trucks.Towing ratings depend on more than the engine. A bigger torque figure only increases towing ratings if the axles, cooling, brakes, and frame can handle it. Watch for what GM says about the transmission and rear axle when full specs come out.GM has taken a very public swing at Ford before revealing a single rating. That's either confidence or bravado, and we'll know which when GM publishes the numbers.Images Via: GMAdvertisementAdvertisementThe post GM's 8.3L Duramax "Mongoose" Targets Ford's Power Stroke: What We Know appeared first on The Auto Wire.