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Dodge diesel trucks and the engines under the hood are among the most popular passenger and work vehicles available. The Cummins diesel engines have a reputation for reliability, and even some of the earliest generations are still on the road. The inventor of the Cummins engine was Clessie Cummins, a farm boy from Indiana. The original Cummins was just a single-cylinder plant and was designed in 1919.
But, Cummins didn’t stop there; he invented another design five years later called the Model F. In 1928, a four-cylinder Cummins diesel called the Model U furthered his ambitions for diesel-powered passenger vehicles. That aspiration was realized in 1929 when a diesel engine was put into a Packard.
The company that Cummins created continued to innovate, eventually purchasing Holset to make in-house turbochargers. The first mass-produced Cummins turbocharged diesel was released in 1980.
5.9L Cummins First Generation Diesel Engine (1989–1993)
The 5.9-liter 12-valve Cummins diesel engine was the first generation to be put in Dodge pickups. The earliest model made 160 horsepower. Many enthusiasts still consider this to be the best Cummins engine due to its simplicity. It was easy to work on and was known for its durability. The D250 and D350 trucks were similarly simple and bare bones, with a lightweight chassis and good fuel economy for the time.
There are still plenty of these old Dodge diesels on the road and working hard. Even though this is a popular generation of Dodge trucks, the best Cummins engine, according to many enthusiasts, would come later.
5.9L Cummins Second Generation Diesel Engine (1994–2002)
The second generation of the Cummins engine was still in the 5.9-liter format, but it added a Bosch P7100 mechanical injection pump. The trucks with this refreshed engine also had an upgraded body design. The second generation was known for its economical and simplistic design, much like the first. Despite the fact that two engines were part of this generation, it’s still considered a single generation in the history of Cummins engines in Dodge trucks.
In the second half of this generation, there were some adjustments, including a switch to the 24-valve Cummins engine. This new version of the engine included an electric-rotary Bosch injection pump. The 12-valve engine improved power over the first generation to 175 horsepower, while the 24-valve engine got up to 235 horsepower.
5.9L/6.7L Cummins Third Generation Diesel Engine (2003–2009)
In the third generation of Cummins engines, the 5.9-liter featured a major update with common-rail fuel injection to improve power and efficiency. It was also quieter compared to previous versions of the 5.9-liter. This engine started out with 305 horsepower and increased to 325 horsepower by 2007.
In the second half of the third generation, the Cummins engine was upgraded to a 6.7-liter design. Right away, this improved the horsepower to 350. Like the 5.9-liter, the 6.7-liter used a high-pressure common-rail system, but it added a Holset variable geometry turbocharger to provide more low-end power. The 6.7-liter was also the first Cummins to feature emissions systems like Exhaust Gas Recirculation and a Diesel Particulate Filter.
6.7L Cummins Fourth Generation Diesel Engine (2010–2018)
The fourth generation of Cummins engines was developed primarily to meet increasingly strict emissions standards. However, it also saw a big jump in horsepower and torque compared to the previous generation. The fourth generation focused on advanced turbocharging, a better fuel delivery system, and the debut of a Selective Catalytic Reduction system with Diesel Exhaust Fluid (DEF) to facilitate cleaner emissions.
The main reason for this generation was to improve emissions, but performance was also improved across the board. With significant aftermarket support and plenty of power, these engines were popular targets for enthusiasts looking to make modifications. Depending on the truck this engine was in, the transmission choice varied between a G56 manual, a 68RFE automatic, and an Aisin automatic.
6.7L Cummins Fifth Generation Diesel (2019–2024) to Next Generation (2025)
The 6.7-liter was upgraded for the current fifth generation of Cummins engines. It now has a standard and high-output version. The former makes 370 horsepower, while the latter makes 400 horsepower. Once again, a full suite of modern emissions equipment is included, such as EGR, SCR, and DPF systems.
The fifth-generation Cummins engine was put in heavy-duty Ram models between the years of 2019 and 2024. It was initially expected to go beyond 2025, but the next generation of Cummins engines is already appearing in the latest models of Ram trucks. This new version of the 6.7-liter engine design has a more robust cylinder block and a new turbocharger. It adds useful features like fast-start and cold-start glow plugs, plus more horsepower. Remote software updates are another technology upgrade.
Which Cummins Generation is Considered the Best?
For the most part, there’s no widespread consensus on which Cummins generation is the best. However, some engines meet certain needs better than others. For example, the best Cummins generation for modern power and technology is either the Fifth Gen engine or the latest one.
For the best balance of power and reliability, the Fourth Gen Cummins engine is considered very reliable, while still being versatile enough for modifications without complex workarounds. For those who enjoy simpler builds or want to do an engine swap, the Second and Third Gen Cummins engines work well for this. The 5.9-liter, 12-valve engine was especially known for its mechanical simplicity and durability.
No matter which Cummins generation engine you have in your rig, ProSource Diesel is your one-stop shop for a wide selection of aftermarket upgrades, replacements, kits, and much more. Visit us today for everything diesel.
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The post Guide to the Five Generations of Cummins Engines appeared first on Prosource Diesel.
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