Cummins Vs Duramax Engines: Key Differences

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Now, that’s the comparison you want to learn about  – two of the top best diesel engines for trucks compared side by side.

Duramax diesel engines are found on Chevy trucks, powering the trucks through any terrain and handling virtually any towing/hauling job smoothly. On the flip side, Cummins engines are installed in Dodge Ram trucks, and they are pretty heavy-duty engines built to handle any task you’d ever use a truck to do.

Comparing Cummins vs Duramax engines is more like comparing the engine performance of Ram and Chevy (GM) trucks.

Let’s quickly look at their key differences and capabilities!

Cummins Diesel Engines

Cummins engines are produced by the American diesel engine manufacturer Cummins Inc., founded in 1919 and headquartered in Columbus, Indiana, United States. Jennifer Rumsey currently heads the company, and it is one of the top global manufacturers of medium and heavy-duty truck engines.

The company’s diesel engines are majorly used in Ram trucks. Cummins has several models of its diesel engine across five generations for Dodge Ram trucks.

Over the years, Cummins engines have been compared with other leading diesel engines, Duramax and Powerstroke. Cummins is a reliable name in the diesel engine market.

Duramax Diesel Engines

Duramax is one of the popular names in the diesel engine market; it is a line of V8 diesel-powered engines manufactured by DMAX, an Ohio-based American manufacturer of diesel engines for trucks.

DMAX is co-owned by Isuzu (40%) and General Motors (60%), and it’s relatively new in the market – announced in 1997.

You’d mostly find Duramax engines in GM Chevy trucks; they come with eight cylinders (V-shaped). Duramax engines are quite powerful and deliver over 500 horsepower on some models. Although new in the market, Duramax engines have been used in over 1,000,000 trucks.

Cummins Vs Duramax: Key Differences

Found in Dodge/Ram TrucksChevy (GM) Trucks
Cylinder HeadCast IronAluminum
Turbo PowerSupportedSupported
SizeVaries by modelsVaries my models
Displacement 6.7L, 408 cubic inches6.6L, 403 cubic inches
Reliability HighNormal
PriceMore expensiveMore affordable

Design and Build

Duramax engines are built as V8 engines with 6.6L displacement, 403.9, and the blocks are made from gray cast iron.

Their engines are sturdy and fortified for all truck operations, varying horsepower rating from 350 – 550 and torque response from 460 – 1,050 lb.-ft. That’s pretty enough to satisfy any diesel-engine enthusiast.

On the other hand, Cummins engines are built as straight-line, six-cylinder diesel engines with varying displacements from 5.9L  to 7.3L. Cummins engines deliver between 300 – 420 horsepower and up to 1,075lbs.-ft or torque. Of course, Cummins has I4, V8, and up to V18 engines for heavy-duty applications.

Performance: Hauling and Towing

Cummins has a special V16 diesel engine with rated horsepower output of 4,400HP, but focusing on the factory-fitted ones installed in Ram trucks, the most you can get out of a Cummins engine (without modification) is 420hp, which is pretty great and powerful.

Duramax diesel engines come with factory horsepower ratings up to 440hp; they produce more HP output than Cummins engines. But Cummins engine produces more torque – up to 1,075 pound-feet- ideal for towing and hauling. Notwithstanding, Duramax can be used to tow heavy equipment and items too.


Truth be told, both Cummins and Duramax engines are reliable – the model you buy determines the amount of HP and torque you would get out of your truck. However, Cummins is the “King” of torque when it comes to diesel engines, and it is the preferred choice of most diesel engine enthusiasts.

Cummins engines are notable for high reliability, but this doesn’t mean Duramax engines are not reliable. How long a Cummins or Duramax engine lasts depends on maintenance and usage. You can put out over 250,000 from these diesel engines, and they’d still be sound.

Frequently Asked Questions

Cummins vs. Duramax, Which Is Better?

Both engines deliver enough power and torque for various trucking activities. However, the majority of diesel-engine lovers would rather pick Cummins over other diesel-powered engines in the market. Why? Cummins is more reliable and gives you more torque.

How Long Can a Cummins Last?

If properly used and maintained, a Cummins diesel engine is certainly going to hit over 350,000 miles hassle-free. Motor Biscuit analysis shows that Cummins engines can last anywhere between 350,000 to 500,000 miles.

How Long Can a Duramax Last?

On different fora and platforms, Duramax loyalists allege that they’ve gotten over 400,000 miles on their diesel engine trucks. Duramax engines are predicted to last well over 300,000 if properly maintained and driven well.


Cummins vs. Duramax is a good comparison, but the final choice between these two engines would depend on what you want from a diesel engine. Notwithstanding, Ram loyalists would always defend the Cummins, while Chevy/GM loyalists would always defend the Duramax – that’s part of the culture.

Duramax engines have the highest horsepower, while Cummins has the highest torque. Both Duramax and Cummins engines are ideal; they produce enough power for the trucks they power. Ford’s Powerstroke engine is the next reliable alternative diesel engine that competes with these two compared here.

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