3 Diesel Engines More Powerful Than The 6.6 Duramax

General Motors launched the first 6.6L Duramax V8, known among diesel engine enthusiasts as the LB7, in 2001 for its heavy-duty pickup trucks. The LB7 Duramax engine design resulted from a collaboration between GM and Isuzu. The design featured first-of-a-kind diesel engine innovations, such as aluminum cylinder heads and common-rail fuel injection (at least among American-made diesel engines for pickup trucks.

In 2001, GM’s 6.6-liter Duramax produced 300 horsepower and 520 pound-feet of torque. While those numbers don’t stack up well against modern HD pickup diesel engines, the LB7’s power was a significant improvement over Ford’s 7.3-liter Power Stroke and the Cummins used by Chrysler in 2001. The Duramax diesel improved over its six generations, gaining more power with each iteration.

The current Duramax generation, a $9,990 engine option for 2026 known as the L5P, is among the best for the 6.6 Duramax. The L5P Duramax debuted in 2017 with 445 horsepower and 910 lb-ft of torque, but refinements over the years have increased its output to 470 horsepower and 975 lb-ft of torque. Those specs are impressive, especially when compared to 2001 diesel engine specs. However, Ford and Cummins have improved their diesel engines, ultimately surpassing the Duramax diesel’s output.

A comparison between the 6.6 Duramax and 6.7 Cummins diesel engines concludes that the inline-six-cylinder Cummins produces 100 lb-ft more torque. While defenders of the popular Duramax will quickly point out that the GM diesel engine makes 40 more horsepower than Ram’s diesel, when it comes to providing the most diesel engine power, torque is a key characteristic.

The 6.7 Cummins is available in Ram pickup trucks as well as the chassis cab configuration popular with commercial truck applications. The current High-Output (HO) version of the fifth-generation Cummins 6.7L engine, available as a $12,995 upgrade for some consumer-grade Ram HD pickup models, produces 430 horsepower and 1,075 lb-ft of torque.

When the 6.7 Cummins was introduced in 2007 as the 5.9 Cummins’ replacement, its output was rated at 350 horsepower and 650 lb-ft of torque. Cummins improved the design over the years, incrementally increasing the 6.7’s horsepower with each passing generation while making bigger gains in torque output.

Ford introduced its 6.7 Power Stroke V8 diesel engine in 2011. That first-generation 6.7, ending with the 2014 model year, ranks among the worst years for the 6.7 Power Stroke engine. Second- and third-generation 6.7 Power Strokes, 2015 to 2019 and 2020 to present, respectively, are generally considered more reliable.

The standard output 6.7L Ford Power Stroke turbo diesel is an $11,495 option for most Super Duty pickups and standard issue for the F-450 and some commercial-grade Super Duty trucks. The latest iteration, available in 2026 Super Duty pickups, produces 475 horsepower and 1,050 lb-ft of torque.

That’s a sizable improvement over the first-generation 2011 6.7 Power Stroke’s 400 horsepower and 800 lb-ft of torque. Ultimately, the standard-output 2026 6.7 Power Stroke makes only five more horsepower than the 6.6 Duramax, but its additional 75 lb-ft of torque is a notable metric to consider.

Ford’s High Output (HO) 6.7 Power Stroke V8 has been the most powerful diesel engine available for consumer-grade heavy-duty pickup trucks since 2023. There are a few differences between the standard and high-output 6.7 Power Strokes, but the power output of the HO 6.7 is substantially higher.

Specifically, the HO 6.7 Power Stroke makes 500 horsepower and 1,200 lb-ft of torque. That gives the HO engine a 25-horsepower and 150 lb-ft of torque advantage over its standard-output stablemate. Compared to the 6.6 Duramax, the HO Power Stroke adds 30 horsepower and 225 lb-ft of torque.

While selecting the optional standard output 6.7 Power Stroke adds $11,495 to the price of 2026 Super Duty pickups, the HO Power Stroke diesel option adds $13,495. Both versions of the 6.7 Power Stroke are available on all Super Duty pickup models; however, the HO 6.7 is required equipment for package options such as the Platinum Plus, Tremor Off-Road, F-250 High Capacity Axle Upgrade, and F-450 High Capacity Gooseneck Tow Package.

In our search for diesel engines with more power than the 6.6-liter Duramax diesel engine used by General Motors, we consulted published specifications and reputable reviews of potentially capable engines. While we found some very powerful units used in large commercial trucks and semi-trucks, we didn’t include them, as comparing commercial big-rigs to consumer pickups is an unfair matchup.

Although the 6.6 Duramax sits at the bottom of the power rankings for diesel-powered pickup trucks, GM loyalists will surely point out that there’s more to owning a diesel pickup than raw power. We won’t dive into the details of the Duramax’s favorable attributes here, leaving that discussion for another time, but we’ll quickly point out that it is the lowest-cost diesel engine option among the four we’ve presented.