If you want to start a debate among diesel enthusiasts, just bring up the topic of 6.7 Cummins and PowerStroke diesel engines and watch the sparks fly. It’s a rivalry as old as time itself. The 6.7-liter Cummins Turbo Diesel and Ford Power Stroke engines are both giants in the diesel world, known for their impressive torque output, towing capabilities, and loyal fan followings. One is the Indiana-born inline-six that is a staple in Ram trucks, while the other is the beloved V8 found in Ford’s Super Duty pickups. On the surface, they do have some similarities, but not much other than their displacement.
The Cummins 6.7-liter turbodiesel was introduced in 2007 as a replacement for the 5.9-liter turbodiesel, the most popular offering in Ram pickups. You can even find it under the hood of the 2027 Ram Power Wagon, a diesel-powered off-road vehicle. The 6.7 has the same solid cast-iron block as the 5.9, but with improved performance and longer service intervals. The engine was updated in 2013, increasing torque output while improving fuel efficiency by 10 percent. For 2019, the fifth-generation Ram HD features a new engine block made of lighter compacted graphite iron and an updated fuel management system, pushing peak torque to more than 1,000 pound-feet.
Meanwhile, Ford’s 6.7-liter Power Stroke engine was launched in 2011 as a replacement for the 6.4-liter Navistar engine. This is Ford’s self-developed V8 engine, code-named “Scorpion”, which uses its own compacted graphite iron cylinder block and Bosch high-pressure fuel injection system. Today, the engine pumps out nearly 1,200 pound-feet of torque.
Read more: There’s a good reason why semi-trucks don’t use V8 engines
engine design
A Ram 3500 work truck outside a dealership – Jetcityimage/Getty Images
The fundamental difference between a Cummins turbodiesel and a Ford Power Stroke is the number of cylinders and how they are arranged. The Cummins is an inline six-cylinder turbodiesel engine, which means six pistons are aligned on a long crankshaft. Inline six-cylinder engines are among the best balanced engines because their piston position essentially eliminates primary and secondary vibrations. Since it uses fewer pistons than the 6.7 Ford V8, it has larger pistons and has a relatively larger bore and stroke. It also offers better low-end grunt, making it ideal for towing applications. The engine layout also lends itself to low stress, meaning that, with proper maintenance, a Cummins power plant can easily span a million miles.
The Ford PowerStroke is a V8 turbodiesel with four cylinders per bank and a short crankshaft. It’s also much more complex than Cummins. The engine uses a counterflow header design, which is different from traditional V8 engines. The latter’s exhaust headers are located on the outside of the engine block, while the Ford’s exhaust tips from the engine’s valley directly into the turbocharger. This reduces turbo lag and makes the engine more responsive. While both engines feature compacted graphite iron cylinder blocks, the Cummins uses traditional cast iron cylinder heads, while the Power Stroke uses lighter aluminum heads.
performance risk
Cummins Turbo Diesel logo on vehicle – Around the World Photo/Shutterstock
In diesel vehicles, the most important statistic is torque. Both 6.7 engines offer incredible amounts of torque, but in different ways, with the Ford 6.7 Power Stroke topping the performance charts. In the high-output version found on top-spec Ford Super Duty trucks, the V8 turbodiesel develops 500 horsepower and 1,200 pound-feet of torque. The 6.7 Cummins turbodiesel isn’t too far behind in performance, though, delivering nearly 430 horsepower and 1,075 pound-feet of torque. It should be noted that despite its simple construction, even its early iteration produced a respectable 370 horsepower and 850 pound-feet of torque.
Peak horsepower and torque figures only tell part of the story. Cummins engines, with their inline-six and turbo setup, deliver torque over a wider rpm range. This allows it to pull heavy loads effortlessly even on steep inclines, while the power stroke pulls heavy loads with brute force. Its peak output is delivered at slightly higher revs, making power delivery more powerful, especially in high-output engine configurations. However, when it comes to the real world, both engines have their place. With its extra torque output, the Power Stroke has a slight advantage in terms of maximum ratings, but that hasn’t stopped people from loving the Cummins replacement.
the end of the abyss
Ford Power Stroke V8 diesel engine under the hood of the vehicle – Hrach Hovhannisyan/Shutterstock
Reliability, longevity and durability form the bottom line for this type of engine. 6.7 Cummins engines have a reputation for bulletproof longevity. Much of this reputation is due to its simple but robust engine architecture, but other considerations have made it a favorite with long-haul fleets and heavy-duty commercial users. The inline six-cylinder configuration leaves a lot of headroom, making service and diagnostics easier. These engines also use the reliable Bosch CP3 high-pressure fuel pump on the 6.7, except for a brief period (2019-2020) when they switched to and recovered from the less reliable Bosch CP4.2.
Early 6.7 Power Stroke engines did have some teething problems with the high-pressure fuel pump and turbocharger. (According to owners, these were the worst years for the Ford 6.7 Power Stroke.) These engines have been using Bosch CP4.2 pumps, which are known for their aversion to poor quality fuel. The new generation (2015 onwards) Power Stroke engines resolve most of the issues and improve durability and reliability. However, in terms of serviceability, the Ford’s V8 engine layout does limit easy access to certain areas. However, compared to Cummins, Ford’s vast dealer network means you can find help even in the most remote areas.
While real-world feedback pushes Cummins ahead in durability, modern power strokes are also quite reliable. The Diesel Engine Forum says both engines will exceed the 300,000-mile mark if properly maintained. Under normal use, most users won’t even get to the point of stressing these engines. All they require is emissions-related maintenance such as regular DPF regeneration and EGR cooler cleaning.
driving experience
Ford F-550 Power Stroke engine under the hood – JoshBryan/Shutterstock
Cummins users are generally impressed with the ample torque available even at low rpm, allowing it to pull heavy loads with minimal fuss. However, its pulling speed is reduced due to the lack of gears in the six-speed transmission. Power Stroke engines feel even more eager to get off the line due to their high power output and the way they’re paired with the 10-speed automatic transmission, which also greatly complements their towing capabilities.
In terms of fuel economy, Cummins engines get relatively low miles per gallon when pulling heavy loads. This isn’t as bad as it sounds, as some Cummins engines can even run on biodiesel. But the 6.7 Power Stroke delivers better fuel economy when fully loaded and driving under highway conditions.
As for the driving experience, the Cummins’ engine layout gives it the roar of an old-school diesel, while the Ford’s V8 configuration delivers a rumbling growl. Remove the emissions control system and you’ll notice that the Cummins sounds like an old tractor, while the Power Stroke sounds like a jet engine. Overall, both engines are towing champions, but the Cummins rig feels like a proper work truck, while the PowerStroke feels like a performance vehicle.
better choice
Dodge 3500 with Cummins engine on display – Hrach Hovhannisyan/Shutterstock
There is no absolute champion here. The 6.7-liter Cummins turbodiesel has earned a reputation for long-distance durability and linear, effortless torque delivery under heavy loads. Featuring a simpler engine architecture and rugged internals, it has a proven track record for reliability and serviceability. Cummins is the powertrain of choice for purists—a commercial engine found in pickup trucks. It’s slow, loud, heavy, and might even outlive you.
By comparison, the 6.7-inch Ford Power Stroke feels like a highly capable beast when you factor in speed, smoothness, and integrated technology. Compared to the raw, rugged nature of the Cummins engine, the Ford V8 engine is quieter and more advanced. The diesel V8 engine combined with the 10-speed gearbox makes for an incredibly fast ride, and when it comes to towing, it’s also a relaxing experience.
The Cummins feels like the old testament of diesel engines, while the Ford Power Stroke feels like the future. If you’re looking for a proven workhorse, the Cummins-powered Ram is your best choice. If you want a fast pickup truck that can also tow a house if needed, the Ford Super Duty should be right up your alley—even if it has another compelling engine option, the gasoline-powered 7.3-liter Godzilla V8.
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