GM Teases New 8.3 Liter Duramax V8 Diesel Called Mongoose for 2027 Silverado HD and Sierra HD
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General Motors has teased a new 8.3 liter Duramax turbo diesel V8 for its heavy duty pickup trucks, and the engine has a rather interesting name: Mongoose.
GM says the new engine will power the refreshed 2027 Chevrolet Silverado HD and GMC Sierra HD. For now, the company has revealed the displacement and the engine’s name, but it has not released official horsepower, torque, towing or payload figures.
That leaves plenty of questions unanswered, but one thing is already clear. GM wants this new Duramax to be part of the ongoing horsepower and torque battle between America’s biggest heavy duty truck makers.
GM Mongoose 8.3 Liter Duramax: What We Know
The new engine is officially described by GM as an 8.3L Turbo Diesel V8. It will sit at the heart of the refreshed 2027 Chevrolet Silverado HD and GMC Sierra HD.
Here is what GM has confirmed so far:
| Detail | GM Mongoose |
|---|---|
| Engine Type | Turbo diesel V8 |
| Displacement | 8.3 liters |
| Engine Family | Duramax |
| Name | Mongoose |
| Applications | 2027 Chevrolet Silverado HD and GMC Sierra HD |
| Horsepower | Not announced |
| Torque | Not announced |
| Towing Capacity | Not announced |
| Payload | Not announced |
GM has not yet provided detailed technical specifications for the new engine. The automaker says more information will come later.
So, for now, the 8.3 liter displacement is the biggest confirmed number.
Why Is GM Calling It Mongoose?
The name is not random.
Ford’s 6.7 liter Power Stroke diesel V8 is associated with the internal nickname Scorpion, and GM’s teaser clearly plays on that connection.
Ford’s current high output 6.7 liter Power Stroke V8 produces 500 horsepower and 1,200 lb ft of torque. Ford lists those figures for its high output Power Stroke in the Super Duty lineup.
GM’s teaser uses a mongoose going after a scorpion. The message is fairly obvious without needing a marketing degree to decode it.
GM is targeting Ford’s diesel V8.
8.3 Liter Duramax vs 6.7 Liter Power Stroke
The displacement difference is significant.
Ford’s Power Stroke uses a 6.7 liter V8, while the new Duramax increases that figure to 8.3 liters.
| Engine | Displacement | Horsepower | Torque |
|---|---|---|---|
| GM Mongoose Duramax | 8.3L | Not announced | Not announced |
| Ford High Output Power Stroke | 6.7L | 500 hp | 1,200 lb ft |
| Current GM Duramax | 6.6L | 470 hp | 975 lb ft |
The Ford figures are official. The current GM Duramax figures are also official, while the Mongoose figures remain unknown.
That last point is important. A larger engine does not automatically tell us its horsepower or torque output. GM still needs to reveal the actual numbers.
Current 6.6 Liter Duramax Is Being Replaced
The Mongoose represents a major jump over GM’s current heavy duty diesel.
The existing 6.6 liter Duramax V8 produces 470 horsepower and 975 lb ft of torque. GM lists the engine with a 10 speed Allison automatic transmission in the current Silverado HD and Sierra HD.
The new 8.3 liter engine will replace that powerplant in the 2027 Silverado HD and Sierra HD.
That means GM is not simply giving the existing Duramax a small update. The company is moving to a considerably larger diesel V8.
GM Is Taking Aim at Ford
Heavy duty pickup trucks remain one of the areas where the traditional Detroit manufacturers continue to push internal combustion technology.
Ford’s high output 6.7 liter Power Stroke currently makes 500 horsepower and 1,200 lb ft of torque.
GM’s current 6.6 liter Duramax makes 470 horsepower and 975 lb ft.
That gives Ford a 30 horsepower and 225 lb ft advantage over the current Duramax.
GM has not said exactly how much power the Mongoose will produce. However, the engine’s larger 8.3 liter displacement and the direct messaging around Ford’s Scorpion make the competition difficult to miss.
For now, anything beyond that is speculation.
2027 Silverado HD and Sierra HD Get the New Diesel
GM has confirmed that the Mongoose will be used in the refreshed 2027 Chevrolet Silverado HD and GMC Sierra HD.
These are the heavy duty versions of GM’s full size pickups, designed for customers who need serious towing and hauling capability.
The current Silverado HD, for example, offers the 6.6 liter Duramax with up to 470 horsepower and 975 lb ft of torque, while maximum available towing reaches 36,000 pounds in the current lineup when properly equipped.
GM has not yet announced the maximum towing capacity of the 2027 trucks with the Mongoose engine.
That figure could become just as important as the horsepower and torque numbers when GM finally releases the complete specifications.
When Will GM Reveal Mongoose Specifications?
For now, GM is treating the Mongoose as a first look.
The company has confirmed the 8.3 liter Duramax turbo diesel V8, its Mongoose name and its application in the refreshed 2027 Silverado HD and Sierra HD. GM has also said that Chevrolet and GMC will have more information to share.
So we are still waiting for the numbers that really matter to HD truck buyers:
- Horsepower
- Torque
- Maximum towing capacity
- Payload capacity
- Transmission details
- Fuel economy
- Engine construction and technical specifications
Until GM releases those figures, the Mongoose remains a very large question mark with an even larger displacement.
GM Mongoose Duramax: What It Means
The new 8.3 liter Duramax Mongoose puts GM directly back into the heavy duty diesel arms race.
The current Duramax already produces 470 horsepower and 975 lb ft of torque, but Ford’s high output Power Stroke has moved to 500 horsepower and 1,200 lb ft.
GM has now responded with a much larger 8.3 liter diesel V8.
The interesting part will not be the name or the displacement. It will be the final numbers.
Until those arrive, the Mongoose is best viewed as GM’s next big move in the heavy duty diesel battle, rather than a truck engine whose performance specifications are already known.
Sources & References
Official sources
- General Motors Newsroom
GM Mongoose 8.3L Duramax official announcement
GM’s official announcement confirming the 8.3L Turbo Diesel V8, Mongoose name and its use in the 2027 Silverado HD and Sierra HD. - Chevrolet Silverado HD
Official Chevrolet Silverado HD page
Useful for current Silverado HD engine, horsepower, torque and towing specifications. Chevrolet lists the current 6.6L Duramax at 470 hp and 975 lb ft. - GMC Newsroom
GMC Newsroom
Official GMC source for Sierra HD news, specifications and future product updates. - Ford Super Duty
Official Ford Super Duty information
Useful for comparison with Ford’s Power Stroke diesel lineup. - Ford 2026 Super Duty Towing Guide
Ford Super Duty Towing Guide PDF
Ford’s official specifications show the high output 6.7L Power Stroke at 500 hp and 1,200 lb ft, with up to 40,000 pounds of towing capability when properly equipped.
Independent automotive sources
- Car and Driver
Car and Driver: GM Mongoose Duramax report
Independent US automotive publication covering GM’s Mongoose announcement and its connection to Ford’s Scorpion nickname. - GM Authority
GM Authority: Mongoose 8.3L Duramax
GM focused publication with additional background on the 8.3L engine and the earlier reporting surrounding it. - The Drive
The Drive
Independent automotive publication useful for additional context and analysis of new truck technology. - Road & Track
Road & Track: GM 8.3L Duramax Mongoose
Independent coverage focused on the new 8.3L Duramax and its role in GM’s heavy duty trucks. - The Fast Lane Truck
TFLtruck: GM 8.3L Duramax Mongoose
Truck focused publication with detailed coverage of the new Duramax and GM’s heavy duty pickup program. - GM-Trucks.com
GM-Trucks.com: 8.3L Mongoose Duramax
GM truck focused independent site covering the Mongoose announcement and 2027 Silverado HD and Sierra HD.
GM Mongoose 8.3 Liter Duramax FAQ
Here are the key questions and answers about GM's new 8.3 liter Duramax Mongoose diesel V8 for the 2027 Silverado HD and Sierra HD.
What is the GM Mongoose Duramax engine?
The GM Mongoose is a new 8.3 liter turbo diesel V8 from General Motors. It belongs to the Duramax engine family and is being developed for GM's heavy duty pickup trucks.
GM has confirmed the engine's 8.3 liter displacement and its Mongoose name, but horsepower and torque figures have not yet been announced.
Source: GM News
Which trucks will get the 8.3 liter Mongoose Duramax?
GM has confirmed that the new Mongoose Duramax will be used in the 2027 Chevrolet Silverado HD and 2027 GMC Sierra HD.
These are GM's heavy duty full size pickup trucks, aimed at customers who need substantial towing and hauling capability.
How much horsepower and torque will the Mongoose Duramax produce?
GM has not announced the horsepower or torque figures for the 8.3 liter Mongoose Duramax yet.
The current 6.6 liter Duramax produces 470 horsepower and 975 lb ft of torque, while Ford's high output 6.7 liter Power Stroke produces 500 horsepower and 1,200 lb ft of torque. The Mongoose figures remain unconfirmed.
Why is GM calling the new Duramax engine Mongoose?
The Mongoose name appears to be a direct reference to Ford's Scorpion nickname associated with its 6.7 liter Power Stroke diesel V8.
GM's teaser uses a mongoose attacking a scorpion, making the competitive message fairly clear. GM has not released detailed performance figures for the new engine yet.
How does the 8.3 liter Mongoose compare with Ford's 6.7 liter Power Stroke?
The Mongoose has a larger displacement than Ford's 6.7 liter Power Stroke, with 8.3 liters versus 6.7 liters.
Ford's high output 6.7 liter Power Stroke is rated at 500 horsepower and 1,200 lb ft of torque. GM has not announced the Mongoose's horsepower or torque, so a direct performance comparison is not possible yet.
Source: Ford Super Duty
Will the Mongoose replace GM's current 6.6 liter Duramax?
Yes. The new 8.3 liter Mongoose Duramax is set to replace GM's current 6.6 liter Duramax V8 in the 2027 Silverado HD and Sierra HD.
The current 6.6 liter Duramax produces 470 horsepower and 975 lb ft of torque and is paired with a 10 speed Allison automatic transmission in the current heavy duty trucks.
Source: GM Powered Solutions
What will be the towing capacity of the 2027 Silverado HD and Sierra HD with the Mongoose?
GM has not announced the towing capacity of the 2027 Silverado HD and Sierra HD with the new Mongoose engine.
For comparison, the current Silverado HD can tow up to 36,000 pounds when properly equipped. The final towing figure for the new 8.3 liter Duramax will depend on the truck configuration and GM's official specifications.
Source: Chevrolet Silverado HD
When will GM reveal the full specifications of the Mongoose Duramax?
GM has confirmed the engine's 8.3 liter displacement, Duramax family name, Mongoose name and application in the 2027 Silverado HD and Sierra HD.
However, the company has not yet released complete specifications such as horsepower, torque, towing capacity, payload, fuel economy and detailed engine construction. More information is expected as GM moves closer to the 2027 truck launch.
Source: GM News
