The Mongoose is loose!
General Motors has revealed the official specifications for the new 8.3-liter V8 diesel engine it calls the Mongoose that’s debuting with the 2027 Chevrolet Silverado HD and GMC Sierra HD.
The turbocharged engine is rated at 555 hp and 1,230 lb-ft, making it the most powerful engine in the heavy duty truck segment, including the gas ones.
The GM trucks also have an updated version of the latter. Their 6.6-liter V8s are rated at 412 hp and 472 lb-ft. Ford’s PowerStroke 6.7-liter turbodiesel V8 is offered with up to 500 hp and 1,200 lb-ft while Ram’s 6.7-liter Cummins 6.7-liter turbodiesel straight-six is rated at 430 hp and 1,075 lb-ft.
GM says the diesel good for up to 20,000 pounds of conventional towing and 38,000 pounds of gooseneck towing in properly equipped trucks. The 38,000-pound figure is 2,000 more than the outgoing 2026 trucks can do with their 6.6-liter turbodiesel V8s, while it is 2,000 less than the F-Series Super Duty’s top tow rating.
“This new diesel engine is the culmination of decades of GM diesel development and integration,” said Norman Peralta, Executive Chief Engineer, Global Engine and Battery Systems. “From the clean-sheet architecture and combustion system to the cooling, aftertreatment and transmission calibration, this is a powertrain built with heavy duty purpose and pride.”
GM says the new 8.3-liter is about more than max power, however, and provides a wider torque curve and improved refinement. The trucks are also the first heavy duty models with electrically assisted rack and pinion steering and are equipped with electronic brake-boosting systems that provide a more linear, predictable pedal feel while better supporting electronic driver aids like adaptive cruise control and automatic emergency braking.
Full pricing and lineup details will be released closer to when the trucks go on sale late this year.
