The big three pickup truck manufacturers have offered trucks with diesel engines for more than 30 years. But the history of the diesel engine goes back to the 1890s, brought to life by Rudolf Diesel, a French inventor. He was looking for an alternative to the steam engine. It seems like he found it.
Over the decades, diesels have been valued for their high torque high-efficiency output. Diesels are known as workhorses, pulling heavy loads without complaint. People have put them in everything from railroad locomotives to zeppelins to submarines.
Pulling power is still the main reason that people buy diesels. Still, savvy engine builders have pushed into the performance arena, turning up the horsepower to rival gas-engine race cars.
Today, most heavy-duty pickup trucks have a diesel engine option for drivers who need more horsepower and torque than a gas power plant can provide. The technology has evolved over the years, delivering unmatched performance and fuel economy. Diesels are the motive power of choice on farms, construction sites, and oil patches, as well as drag strips, boat ramps and campgrounds.
While diesel engine builders have come and gone over the years, the top three currently available in pickups are Cummins, Ford’s Powerstroke, and GM’s Duramax. Of course, these engines come with a truck wrapped around them. The engine type usually aligns with the make of truck it came in, at least as an OEM configuration.
Long the domain of the heavy-duty or light commercial level of pickups, diesels are starting to show up in smaller trucks. The Chevy Colorado and GMC Canyon offer a 2.8L four-cylinder that returns up to 30 mpg. Ford recognized the demand for a diesel in the F-150 and bolted in a Power Stroke that should get up to 30 mpg on the highway.
We’ll look at the three big-time engine builders in the market today, but keep in mind some comparisons have as much to do with the truck it’s attached as the engine.
C.L. Cummins began making diesel engines in Columbus, Indiana, in 1919. Within six years, the company offered the first 100,000-mile warranty. Since then, Cummins has cemented its reputation as a builder of reliable diesels. You’ll find Cummins diesels in a wide range of heavy-duty and vocational vehicles, including buses and garbage trucks.
A Cummins diesel first appeared in a Ram pickup in 1989. It was a 5.9L six-cylinder 12-valve turbodiesel engine that generated 160 horsepower and 400 lb.-ft. Other trucks were available with diesels, but turbocharging took diesel performance to the next level.
The venerable first-generation Dodge Ram D-250 and D-350 models from 1989-1993 featured the 160-hp, 400 lb-ft 5.9-liter 12-valve Cummins. You’ll still them toiling away, racking up six-figure mileage. Cummins is still the diesel offering for Ram Trucks, which before 2010 were known as Dodge Ram trucks. You’ll also find a Cummins under the hood of the Nissan Titan XD.
The current 6.7L Cummins in Ram trucks is known for its steady flow of power and lower noise output. The light weight of the robust graphite iron engine block cuts down fuel consumption without affecting power. It’s also B20 biodiesel compatible.
On the performance front, it runs with a 16.21:1 compression ratio, fed by a Bosch high-pressure common-rail fuel system, comes paired with a Holset HE351VE variable geometry turbocharger.
Cummins was the first to crack the 1,000 lb.-ft. torque barrier for general-use trucks with the 2020 Ram 3500 Heavy Duty. That’s one of the reasons Cummins-equipped Ram trucks are a favorite choice for those looking for a capable tow vehicle.
Chevrolet started its diesel odyssey with a 5.7L Oldsmobile engine, putting out 120 hp and 220 lb.-ft. Then GM partnered with Detroit Diesel in 1982 to build a 6.2L V8 that put out 130 hp and 240-lb.ft. After about 20 years, GM formed a new venture with Isuzu to create the Duramax class.
Over the years, the GM updated the Duramax to improve performance and meet emissions standards. With each model, The Duramax improved in durability, power, fuel efficiency and lower noise. However, Duramax has never quite matched the best that Cummins and Power Stroke have had to offer. The 6.2L and 6.5L GM engines built from 1982-2000 were valued for their fuel economy in light towing usage and didn’t match up to the Cummins or Power Stroke. Adding a turbo and tweaking the injection pump on the early naturally aspirated version could bring it up to snuff, and later turbo models were more competitive. A host of issues typically limited lifetime to about 400,000 miles, according to Driving Line.
The current Duramax Diesel engine was designed with unique features to provide more power without compromising fuel economy or longevity. These elements include an electronically controlled variable-geometry turbocharger, a Venturi Jet drain oil separator, and cold-start technology.
Ford launched its first diesel offering in 1982 in a partnership with International Harvester, which later became Navistar International. In 1994, Ford and Navistar International debuted the first Power Stroke diesel engine. The 7.3L Power Stroke engine featured direct injection that put out 215 hp and 425 lb.-ft. of torque. Ford and Navistar parted ways in 2009, and in 2011 Ford debuted the 6.7L Power Stroke Scorpion.
The 6.7L has become a favorite of drag racers, with the high-pressure common rail system and an appetite for handling copious amounts of boost.
Here’s a comparison of the best options for given duty applications. There isn’t a wrong choice in most cases, but one may perform better for you. To some extent, it’s like Red Sox vs. the Yankees, The Beatles vs. the Rolling Stones, or Camaro vs. Mustang. You like what you like, and not always for rational reasons.
Cummins was the first to crack the 1000-lb. ft. limit with the Ram 3500 Heavy Duty, with the 400 hp High Output I-6, with a six-speed transmission. The combination could hand up to 35,100 pounds of towing capacity.
Currently, Ford’s 6.7 Power Stroke V8 makes the F-350 Super Duty the big daddy of the heavy-duty pickups. The 450 hp, 1050 lb.-ft. of torque are channeled through a 10-speed automatic transmission. The combination can tow up to 37,000 pounds in trucks apportioned for commercial operation.
Although diesels are designed to run thousands of miles, just about every engine type has suffered from a bout of poor reliability. Common failure points have been common: leaky heads, fuel injectors, turbochargers, and exhaust gas recirculation systems.
Motor Trend magazine calls the last generation of the Power Stroke 7.3L V8 in 1999-2003 F250s and F350s as one of the most reliable engines in recent years. It’s not uncommon to see engines with 500,000 miles when properly cared for, thanks to the hardened internal components and the hydraulically actuated, electronically controlled unit injector (HEUI) fuel system that stops the engine from running if the oil is low. The 7.3L can run 200,000 miles before it’s time to overhaul the injectors. The six-bolts-per-cylinder head design and the low stock cylinder pressure contributed to its long life.
The Duramax 6.6L is a key ingredient in one of the best heavy-duty offerings in the Chevrolet/GMC 2500HD and 3500HD. The Duramax, coupled to the 10-speed automatic transmission, puts out 445 hp and 910 lb.-ft., hefty enough to tow up to 35,500 pounds in the regular cab dually configuration.
If you’re looking for an engine that will withstand your plans for insane amounts of power, consider the 6.4L Power Stroke from 2008-2010 F-250s and F350s. Motor Trend says the compound turbocharged 350 hp can be massaged to fulfill any pulling dreams you have. If there are any doubts, know that it scored very well in a series of Diesel Power Challenge events.
If you’d like to go old school, check out the 2006-2007 Chevrolet/GMC 2500HD and 3500HD. They’re the last of the pre-emission engines from GM. The 6.6L Duramax V-8 is easy to modify due to the lower level of complexity. It has real hot-rod potential and is still a great everyday workhorse.
We’ve compared Duramax, Power Stroke and Cummins engines, but all the data doesn’t answer the real question. Which one is best? Like many things in life, it all depends. Will a few pound-feet of torque matter in your everyday life or make a hundredth of a second difference in the Ultimate Callout Challenge?
What do the numbers tell you? The current Power Stroke has more horsepower but less torque than the Cummins. But the Power Stroke may be able to pull faster in real-life driving. For high-performance applications, the Duramax options lag behind. But in daily use, you may not notice.
Cummins has the edge in long-term diesel design and building experience. But the newcomers from Ford and GM have pushed Cummins away from complacency.
If you’re embarking on a high-performance build, a weak head stud or fastener can be catastrophic for the performance and the life of your vehicle. All three engines will benefit from upgrading the cylinder head fasteners. Stock engines come with Yield to Torque (YTT) or standard head bolts. The OEM fasteners may not handle the load if you’re boosting horsepower and compression ratio. Step up to head studs from TrackTech Fasteners®, which are engineered and constructed for strip and circuit performance for Ford Power Stroke, Chevy Duramax and Ram Cummins applications. The stud design makes removing and replacing the cylinder head and re-using the same fasteners easier. TrackTech head studs are proven in testing labs and at the track, standing up to greater extremes than any other brand in their class.
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