When you think of diesel-powered pickup trucks, you can’t help but think of Cummins. The legendary engine manufacturer has been at the heart of RAM's heavy-duty trucks for decades, shaping the performance, reputation, and capabilities of these legendary workhorses.
In this article, we’re taking a look at how Cummins engines have evolved over the years, powering RAM trucks from the early days to today’s high-tech beasts.
The partnership between Cummins and RAM (then known as Dodge) began in 1989, with the introduction of the first Cummins turbocharged diesel engine in the Dodge RAM 2500 and 3500 models. This was a groundbreaking moment for the light-duty and heavy-duty truck market.
Prior to this, diesel engines were primarily used in commercial trucks, and the idea of putting a turbocharged diesel into a consumer pickup truck was revolutionary.
The engine that debuted in the first-generation RAM trucks was the 12-valve 5.9L Cummins. This engine produced 160 horsepower and a robust 400 lb-ft of torque, a massive leap forward from the gasoline engines that were common in trucks at the time.
The 5.9L Cummins quickly became a favorite among truck enthusiasts and commercial operators, offering superior towing capabilities, reliability, and fuel economy compared to the competition.
In 1994, the second-generation RAM trucks arrived, and so did the continuation of the mighty 12-valve engine, which had quickly become known for its reliability, simple design, and ease of maintenance.
The second-generation 12-valve RAMs were available with both manual and automatic transmissions, and the engine output was increased to around 160-215 horsepower (depending on the model year), with torque figures approaching 440 lb-ft.
By the late '90s, the newly introduced 24-valve Cummins engine had become a favorite for anyone needing serious towing capability—particularly in the 3500-series models, which were built for heavy-duty commercial work.
The third generation of RAM trucks marked a significant shift in both engine technology and emissions standards. In 2003, the 5.9L Cummins engine underwent major updates, which included the addition of a common-rail fuel injection system. This change resulted in improved fuel efficiency, greater horsepower, and lower emissions—though the latter was a challenge in the diesel world at the time.
The most notable upgrade during this period was the switch from the 5.9L engine to the larger, more powerful 6.7L Cummins I6—beginning halfway through the 2007 model year.
Power output increased significantly, with the third-generation trucks boasting up to 350 horsepower and 650 lb-ft of torque in certain configurations. The truck’s towing capacity increased as well, making the RAM 3500 one of the most capable heavy-duty pickups on the market.
One of the hallmark features of this era was the inclusion of a six-speed manual transmission or an automatic with an available exhaust brake—a crucial feature for controlling trailer weight and ensuring smooth towing.
This was also the era that saw the introduction of Diesel Particulate Filters (DPF), a response to the stricter emissions standards introduced by the EPA. While these changes added complexity to the engine, they also reflected RAM's commitment to staying ahead of regulatory requirements while maintaining their performance edge.
The fourth-generation RAM trucks, launched in 2010, brought another leap forward in both technology and performance. The new engine was designed to handle even higher power outputs while meeting increasingly stringent emissions regulations.
The 6.7L Cummins turbo-diesel engine was offered with two (2) six-speed automatic transmission options, as well as the G56 6-speed manual. By 2018, the engine produced up to 385 horsepower and an impressive 930 lb-ft of torque (when properly optioned).
In this generation, RAM also made significant improvements to ride quality, thanks to a redesigned suspension system, while also upgrading the interior, making the trucks more comfortable for daily driving. The combination of heavy-duty performance and better everyday usability made the fourth-gen RAM with the 6.7L Cummins a top choice for both fleet operators and casual truck owners who demanded the best of both worlds.
Sadly, for diesel owners who prefer to row their own gears, 2018 was the last model year that RAM offered the 6-speed manual G56 transmission.
The fifth-generation RAM trucks, introduced in 2019, marked a new chapter for both Cummins and the RAM brand. This was an era defined by the quest for even more power, efficiency, and technology. The Cummins 6.7L engine continues to be the heart of the heavy-duty RAM lineup, but the latest iteration has undergone major improvements.
One of the standout features of the newest Cummins-powered RAMs is the available 1,075 lb-ft of torque—a number that was unheard of in the diesel truck market just a decade ago. This makes the RAM a seriously capable platform.
In addition to the increased power, RAM has embraced cutting-edge technology, integrating features like adaptive cruise control, lane-keeping assist, and a 12-inch touchscreen infotainment system. These advancements help make long hauls more comfortable while maintaining the truck's legendary capability.
As of 2025, the RAM 3500 with the 6.7L Cummins continues to be the benchmark for heavy-duty pickups, with future innovations in emissions technology, powertrains, and towing capabilities likely on the horizon.
There's talk of hybridization and even fully electric powertrains for the RAM lineup, but the diesel engine—especially the Cummins—remains a critical component for drivers who need uncompromising power.
The next generation of RAM trucks will likely push the limits of towing, efficiency, and digital integration even further, with Cummins continuing to refine their iconic diesel engine for even greater performance.
From the early days of the 5.9L turbo-diesel to the current 6.7L powerhouse, the partnership between Cummins and RAM has been one of mutual success and innovation. Over the decades, Cummins engines have powered RAM trucks through major technological shifts, environmental challenges, and performance benchmarks.
Whether you're a weekend warrior, a commercial operator, or just someone who appreciates a truck that gets the job done, Cummins-powered RAM trucks have earned their reputation as some of the hardest-working machines on the road.
When it’s time to upgrade your Cummins-powered RAM, FASS Motorsports has everything you need. From lift kits to lights and so much more, we’re proud to be a one-stop-shop for RAM owners.
Located in Washington, Missouri, we provide a comprehensive experience—from hassle-free consultations to installations and custom-ordered parts. To get in touch with us, shoot us a message on any social media platform, call us at (636) 429-7020, or email us at info@fassmotorsports.com.