What is the Duramax “Mongoose” Diesel?

Duramax Mongoose Engine, hood badge, — Duramax Mongoose Diesel Engine

The “Mongoose” is General Motors’ new heavy-duty pickup-truck diesel engine. Scheduled to debut in the 2027 Chevrolet Silverado HD and GMC Sierra HD, the Mongoose is offered as an option to the standard 6.6-liter gasoline V8 powerplant.

What is the Duramax “Mongoose” Diesel?

Mongoose

Internally designated LP6, the big 8.3-liter turbocharged V8 replaces the Duramax 6.6-liter diesel in GM’s HD pickups.

The Mongoose is a clean-sheet, in-house design. The nickname is a deliberate jab at Ford, which equips its Super Duty pickups with a 6.7-liter turbodiesel engine codenamed “Scorpion.” This as mongooses are natural predators of scorpions.

Engine Specs

The new engine includes a graphite-iron block, forged steel crankshaft and connecting rods, steel pistons, a variable-geometry turbocharger, dual-stage air-to-water intercooling, and will be mated to anAllison-brand 10-speed automatic transmission.

Properly equipped a Mongoose powered pickup is rated to tow up to 38,000 pounds.

Mongoose versus Power Stroke versus Cummins

Here is a look at how the Mongoose engine compares to Ford and Ram heavy-duty diesels in terms of horsepower and torque output ( horsepower/pound-feet torque):

GM Duramax 8.3-liter “Mongoose” 555/1230
GM 6.6-liter (2026) 470/975
GM 6.6-liter “gasser” 421/472
Ford 6.7-liter Power Stroke “Scorpion” 500/1200
Ram 6.7-liter Cummins 430/1075

Note that the Ram Cummins engine is a 6 cylinder, while the other powerplants are V8s. Plus, a lower-output version of the Power stroke is also offered.

Largest General Motors Engine

Though several recent headlines have proclaimed the Mongoose GM’s largest-ever engine, the automaker has produced a pair of even greater displacement powerplants. Have a look:

1960-1966 GMC “Twin Six” 702-cubic-inch V12 (11.5-liter)
1967-1972 GMC 637-cubic-inch V8 (10.4-liter)
2027 “Mongoose” 507-cubic-inch V8 (8.3-liter)
1970-1976 Cadillac 500-cubic-inch V8 (8.2-liter)
2001-2006 “Vortec” 496-cubic-inch V8 (8.1-liter)

Note that the Silverado HD and Sierra HD are significantly updated for 2027, with an emphasis on payload and towing capability. A freshening of exterior and interior trim is also part of the enhancement plan.