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Duramax vs. Cummins vs. Power Stroke - What are the Differences?

By Autolist Staff | September 17, 2019

Pickup truck owners and buyers are often extremely loyal to a particular brand, and this is especially true of truck buyers who buy diesel trucks. The three top names in the American diesel truck market are General Motors' Duramax, Ford's Power Stroke and Cummins. The latter has mainly been used in Fiat Chrysler's Ram 2500 and 3500 trucks, but their engines are also in the Nissan Titan XD.

Is one of these engines better than the other, or are there simple differences? The best choice depends on what the consumer wants it to do. Here's a breakdown of all the differences between these three pickup truck diesel brands.

Which Engine is Older?

Cummins got its start in 1919, and started supplying diesel engines to then-Chrysler Corporation's Ram pickup trucks in 1988. In contrast, the GM Duramax line has only been around since 2001. The Ford Power Stroke name has been in use since 1994. Even if you go back beyond the brand names of the GM and Ford engines, Cummins is still older. When you compare Duramax against Cummins and Power Stroke, there's no doubt that Cummins engines win in the age department.

Which Engine Produces More Torque?

The significant reason large, heavy-duty trucks exist is to tow things. To tow, you need a lot of torque. Diesel engines are capable of producing a lot more torque versus gasoline engines. That is due to their longer and more steady combustion process, which allows for longer connecting rods.

The 2019 Ford F-Series Super Duty with the 6.7-liter Power Stroke turbodiesel engine produces 935 lb.-ft. of torque. Meanwhile, the 2019 Chevy Silverado HD and the similar GMC Sierra HD Duramax diesel engine make 910 lb.-ft. of torque. The Nissan Titan XD has a 5.0-liter Cummins turbodiesel engine, but it only manages 555 lb.-ft. of torque. However, the Ram Heavy Duty's 6.7-liter Cummins engine produces 930 lb.-ft. And the larger and more luxurious Ram 3500 Laramie produces 1,000 lb.-ft. of torque.

Apart from the smaller Nissan, all of the domestic brands are relatively close in terms of torque. Other factors, including how much they weigh and how much optional equipment they have to carry all of the time, will affect performance to some degree.

What About Horsepower?

Torque is ultimately more important for towing, but horsepower is also a factor. With more horsepower, the truck can accelerate faster whether or not it's towing anything. If you need to speed up quickly while hauling a heavy load, you'll appreciate extra horsepower. In this category, Power Stroke and Duramax are very close at 450 for the former and 445 for the latter. The Cummins engine in Ram trucks produces 400 horsepower. Again, Power Stroke takes the prize in this category with the most horsepower, albeit by a small margin.

Towing Power

Torque and horsepower are significant factors in how much a truck can tow. But two other factors play a part. The first is the structural design of the truck itself, and the other is the engine's strength. It's important to realize, however, that in the United States, towing over 26,000 pounds requires a commercial drivers license. Both the Ram Cummins and the Ford Power Stroke can pull over that amount, but the Duramax lags with a total towing capacity of 23,300. The Power Stroke wins here again with a total towing amount of 34,000 pounds versus the Ram's 31,210 pounds. However, if you're looking at these numbers and do not hold a commercial license, any of these trucks will likely fit the average truck owner's requirements.

Does Fuel Economy Matter?

Ultimately, heavy-duty diesel trucks are meant to do work, not garner excellent fuel economy. In fact, we don't know the fuel economy of these vehicles since they are too large to be rated by the EPA like light trucks. But given that diesels are generally more efficient than gasoline engines, these diesels may allow for a longer driving range in normal driving.

However, two of the three big names in diesel do put their engines in smaller vehicles as well. General Motors puts the four-cylinder diesel in the Chevrolet Colorado and the GMC Canyon, while Ford puts a V6 Power Stroke in the F-150. The former engine is a 2.8-liter four-cylinder that manages 30 mpg on the highway while the Ford has a 3.0-liter V6 diesel that gets 26 mpg on the highway in the Lariat trim. In this situation, it depends on what matters more to the truck buyer.

Warranty and Reliability

Probably even more important than engine specs is a guarantee of reliability. Long warranties don't necessarily mean that the engine is guaranteed to work that long, but rather that any issues will be addressed if they happen during that period. Not only that, but the manufacturer likely has a reasonable assumption that the engine will last that long. If they didn't, they wouldn't make a warranty where they'd lose money as issues continued to crop up. In terms of light-duty trucks, the Nissan Titan XD with the Cummins diesel has a 100,000-mile bumper-to-bumper warranty. That type of warranty is on par with a lot of other vehicle warranties in the industry. However, Ford goes further with a 250,000-mile warranty on the Power Stroke engine in Class 6 and 7 medium-duty trucks. These are not trucks for the average truck buyer, but that's a big boost for peace of mind in commercial fleet circles.

Popularity

For a long time, Cummins has enjoyed superior popularity, but the increasingly better design on the Power Stroke has pushed it well into the running in terms of performance. The main reason is that the two main specs of torque and horsepower are very close. The Power Stroke has more horsepower, but slightly less torque, while the Cummins has the opposite. However, as noted by AutoWise, the Power Stroke ultimately produces more horsepower, which is a better indicator of engine strength in real driving situations.

Full Specs of the 6.7-liter Power Stroke V8 Engine:

  • 409 cubic inches 6.7 liters

  • V8 configuration

  • Pushrod OHV 32 valve, four per cylinder, cam in block valvetrain

  • 3.90 inch bore x 4.25-inch stroke

  • 16.2:1 compression ratio

  • 450 horsepower

  • 935 lb.-ft. of torque

  • Uses ultra-low sulfur diesel and B20 biodiesel

  • Compacted graphite iron engine block

  • Aluminum cylinder heads

  • Direction injection fuel system with high-pressure common rail

Full Specs of the 6.6-liter Duramax Engine LFP V8:

  • 403 cubic inches, 6.6 liters

  • V8 configuration

  • OHV 32 valve, four per cylinder, mechanical roller lifters valvetrain

  • 4.055 inch bore x 3.897-inch stroke

  • 16.0:1 compression ratio

  • 445 horsepower

  • 910 lb.-ft. of torque

  • Uses ultra-low sulfur diesel and B20 biodiesel

  • Cast iron engine block

  • Cast aluminum cylinder heads

  • Direct injection fuel system with high-pressure common rail

Full Specs of the Inline-Six 6.7-literCummins Diesel Engine:

  • 408 cubic inches, 6.7 liters

  • I6 configuration

  • OHV 24 valve, four per cylinder, solid lifter camshaft valvetrain

  • 4.21 inch bore x 4.88-inch stroke

  • 16.2:1 compression ratio

  • 400 horsepower

  • 1,000 lb.-ft. of torque

  • Uses ultra-low sulfur diesel and B20 biodiesel

  • Compacted graphite iron engine block

  • Cast iron cylinder heads

  • Direct injection fuel system with high-pressure common rail