12 Of The Cummins Pickup Truck Engines With The Highest Horsepower

Cummins has been building pickup truck engines since 1989, which is when it first offered its legendary 359 cubic-inch inline-six engine known as the 6BT, often considered one of the best American diesel engines. Since being founded in 1919 by Clessie Cummins, the company has expanded greatly; now building the engines in one of three main plants in the U.S.: namely, the Jamestown factory in New York, the Rocky Mountain facility in North Carolina, and at the Columbus plant in Indiana. From those early days in 1989, to the latest 6.7-liter monster on sale today, Cummins' diesel engines for pickup trucks have come a really long way. Where the initial 6BT had 160 horsepower, the most modern offerings exceed 400; and also makes more than 1,000 lb-ft of torque from rather low RPMs. 

Currently, Cummins engines are available across RAM's heavy-duty lineup, including the 2500 and 3500 pickup trucks for consumer use, as well as the 3500, 4500, and 5500 Chassis cab trucks designed for commercial applications. Additionally, readers may be interested to know that certain Ford and Nissan pickup trucks are also equipped with Cummins engines, even though the brand may be synonymous with RAM trucks. And while there are several rumors floating around the internet that Cummins may be coming out with a 7.2-liter engine for the 2026 RAM, these claims are yet to be substantiated. With all that said, here are 12 Cummins engines that power pickup trucks.

The Cummins 6BT, produced for a decade between 1989 and 1998, was considered the best Cummins diesel engine ever made — but Cummins wanted to improve upon it. That's when it made its first major upgrade, by introducing its newest engine, built on the same bones as the 5.9 that it replaced. The new unit had 24 valves instead of 12, bringing the total up to four valves per cylinder. Other tuning by the engineers brought the rated power output for the automatic variant up to 215 hp and 420 lb-ft of torque, and 235 hp and 460 lb-ft of torque for the manual version. 

This was a marked improvement upon the 5.9 12-valve, as the manual version of the old engine made 215 hp and 420 lb-ft of torque — figures that were now being produced by the automatic variant of the new engine. It was available to order from the same year, being equipped in the RAM 1500, 2500, and 3500. Note that while 235 hp may be three-cylinder eco-pot figures today, back in the day, the 1998.5 Cummins 5.9 was beating out the Ford F-150 by 25 hp, and the Chevy Silverado by 35 hp, with more than double the torque of the Chevy. Furthermore, the 24V version of the 5.9 ISB would run for almost a decade, being replaced in 2007 by the 6.7-liter. However, it would be massively upgraded, as our next two list items will display.

Given that the 1998.5 24V 5.9-liter that we just talked about was already a massive upgrade over the first generation 6BT, it was surprising, to say the least, that Cummins followed up with another big update just four years later. Offered on top of the existing standard output 5.9L ISB that had been in production for 4 years at the time, this was the first high output engine that Cummins introduced. The new high output engine produced 245 hp, and coming in at 505 lb-ft, was the first Cummins pickup engine to exceed 500 lb-ft of gross torque. 

Unlike other Cummins pickup engines, the high-output version was only available to spec with the NV5600 manual transmission, meaning slightly less efficiency — but with torque like that, no one minded. Also, the high-output engine was unfortunately not available for sale in the state of California because of the state's extremely strict emission regulations, meaning California buyers had to settle for the standard output engine and its 235 hp alongside 460 lb-ft of torque. And while 245 hp may sound like it doesn't belong on a list that has "highest horsepower" in the title; it had 25% more power than the equivalent F-150 of the time, which posted 202 hp.

Not satisfied with its progress thus far, Cummins' engineers once again upgraded its engine for the 2003 production year. We should clarify that the second generation 24V 5.9-liter ran from 1994 to 2002, and that the 24V 5.9 engines produced from 2003 to 2007 were so much of an upgrade that it's considered the third generation of the legendary inline-six 5.9-liter powerplant. For starters, the engines had now become completely reliant on electronic systems and sensors to operate, and also began to ship with an all-new fuel injection system from Bosch — common rail, and electronically-controlled, of course. 

This new engine was one of the first iterations to cross the golden barrier of 300 hp at the time. The 555 lb-ft that it posted was simply icing on the cake, which gave the trucks equipped with the high output engine a maximum towing rating of 15,950 pounds for the 3500. Note that only the high output version would make 305 hp, as the standard output would produce 235 hp and 460 lb-ft.

The late-second generation of the Cummins 5.9 ISB is also considered by fans to be among the best years for Cummins diesel engines, and it's easy to see why. Where the mid-stage had gotten an upgrade that pushed it past the 300 hp mark, the 2006 to 2007 unit also got a 20 hp boost, bringing it up to a total power output of 325 hp, which was absolutely stellar for the time. This was alongside a 55 lb-ft boost that brought the peak torque up to a whopping 610 lb-ft; which gave the RAM models on which it was offered a class-leading towing capacity. 

It's worth mentioning that all of this torque was available from just 1600 RPM, giving the RAM pickups of the day amazing performance in the low ranges. Because of this beauty of an engine, the RAM pickups of 2006 and 2007 had class-leading towing capacities. Specifically, the RAM 2500 on which the 5.9-liter Cummins was an option had a towing capacity of 13,700 pounds, and the RAM 3500 on which it was standard was rated for a mind-boggling 15,800 pounds — figures that seemed straight out of a sci-fi movie. Remember that the Ford F-150 in the year had a towing rating of "just" 9,100 pounds — and that's for the top-of-the-line King Ranch version. Additionally, it is also one of the most reliable Cummins pickup engines — which is saying something.

The first modern engine on our list is this one — the 2025 Cummins 6.7 turbo Diesel for chassis cab operations. Yes, it isn't strictly a pickup, but for people who want to customize its chassis cab frame with a bed, it's a very plausible option. It comes with 360 hp and 800 lb-ft — a massive 20% step down from the 2025 Turbo Diesel for pickups that we'll cover later on. However, the chassis cab variant of the 6.7-liter Cummins does make up for this shortfall by having a much better economy, and much higher longevity rating than the pickup version. 

In fact, most chassis cab engines will follow this format: When compared to the pickup-truck versions of the same engine, the chassis cab variants will almost always have lower power and torque, but better efficiency and higher longevity. In addition, the engine is also California Air Resources Board (CARB) and EPA-compliant, and, like the rest of the lineup, features forced induction via a turbocharger. Currently, the 6.7 TD is available on the three main chassis cab RAM models, namely, the 3500, 4500, and 5500. Also, the engine is an exclusive offering for the North American market.

The 68RFE is a six-speed automatic transmission that is often paired to the 6.7-liter Cummins pickup truck engine. In 2013, alongside introducing the Aisin high-output variant of the 6.7, Cummins also gave the 68RFE version a boost. Where the existing automatic variant of the 6.7-liter used to make 350 hp and 800 lb-ft of torque up until 2012, in 2013, it got an additional 20 hp, pushing the total power output to 370 hp. Torque figures didn't get any increase, because Cummins had upgraded the torque output the year prior to 800 hp. 

These figures would remain constant until 2018, which is when Cummins would announce a major change — but more on that in the next section. Additionally, 2013 is also the year when DEF, or diesel exhaust fluid, began to be used as part of a new SCR, or selective catalytic reduction system that was as of the production year standard across the board of Cummins engines.

The next major upgrade for the 6.7-liter Cummins pickup engine wouldn't come until 2019, but that didn't stop the company from giving its outgoing 2018 model a bit of a spec bump. While horsepower remained the same from 2013 to 2018, rated at 385 hp, during this five-year interval, Cummins bumped up the torque twice. The first was a 15 lb-ft increase in 2015, which raised the torque output for the Aisin to 865 lb-ft. The second came in the year that immediately followed, and was a 35 lb-ft bump that brought the 2016 high-output engine to a whopping 900 lb-ft of torque. 

Throughout its production run, the Cummins high-output 6.7-liter engine was an exclusive option on the RAM 3500 model, being offered only alongside the Aisin transmission option, which is where it gets its name from. This powerful engine led to the RAM 3500 having an almost unbelievable towing capacity of 31,210 pounds, making it one of the best trucks ever made in terms of maximum towing capacity that was sold in America. In addition to that phenomenal towing rating, the RAM 3500 on which this engine was offered also had an impressive payload capacity of 7,390 pounds. Furthermore, the smaller RAM 2500 with the standard 6.7-liter Cummins was no slouch either, coming in with a towing rating of 17,980 pounds.

In 2013, Cummins was offering a grand total of three different engine styles. First up, there was the base G56 variant, which was a manual-only transmission that had remained largely unchanged since it was introduced, making the same 350 hp as it did in 2008, but with 10 lb-ft more, at 660 lb-ft versus 2008's 650 hp. The second variant was the one paired to the 68RFE transmission, which, for this production year, made 370 hp and 800 lb-ft of torque. And then, Cummins also introduced the inaugural version of the Aisin engine, available exclusively on RAM 3500 pickup trucks. 

It was a true workhorse, able to produce a maximum of 385 hp alongside an eye-water 850 lb-ft of torque — bit by bit, it was inching closer to the mythical 1,000 lb-ft mark, which it would go on to hit a few years down the line. Also, for the rare instances where customers aren't sure whether its truck has the 68RFE or the Aisin AS69RC six-speed, look for the oil dipstick that can be found on the left-hand side of the engine bay. If the dipstick is on the right, the truck has the Aisin transmission.

The next engine on our list is the Remanufactured Cummins Turbo Diesel, and is a bit of a departure from what we've been covering so far. Power ranges from 325-385 hp and 610-930 lb-ft of torque depending on the model years. To put it simply, it's a way to give an old, broken, or deteriorated Cummins pickup truck engine a new lease on life. When a customer buys a remanufactured engine, they're getting genuine Cummins 5.9L and 6.7L turbo diesel engines that have been completely torn down, rebuilt to factory specs, and tested by Cummins ReCon. At the time of writing, remanufactured engines are only available for purchase through regional and local Mopar dealers.

However, while the price will likely carry a premium (~$21,000 for a 2013-2018 high-output), it lets customers avoid having to buy a whole new truck or dealing with sketchy rebuilt engines from random shops. Instead, these remanufactured engines are for owners whose Cummins diesel has failed or worn out, and gives them a factory-quality replacement engine. There are three main options, with the first being a complete engine that ships with everything needed to install it, so simply drop it in and go. Then, there's the long block, which rebuilds the engine block with internals, and reuses external parts from the existing engine. And lastly, there's the short block rebuild, that has the maximum existing part reuse, with only the block and basic components being rebuilt.

Next, we have the 2019 Cummins 6.7-liter high output engine. As we've mentioned above, 2019 brought in a major upgrade over the 2018 model year. Like the other HO engines produced in the 2010s, this one is also named "Aisin", is paired to an Aisin transmission from where it gets its name, and is offered on the RAM 3500 heavy duty trucks. Notably, this was the first Cummins pickup truck engine that was rated for 400 hp, and was also the first Cummins pickup engine that touched 1,000 hp. It's as if Cummins was specifically gunning to meet these two golden barriers — which, let's be honest, it probably were. 

RAM had also continued to improve its class-leading offering with the RAM 3500, which when paired to this engine, had a towing rating of 35,100 pounds and a payload capacity of 7,680 pounds — both very impressive numbers. Also, RAM decided to kill off the manual gear models this year, meaning that RAMs 2019 lineup was all-automatic. The last thing worth mentioning is that Cummins also added 50 lb-ft of torque to the standard 68RFE engine — remember, the G56 manual was dead by now, which brought power output for the entry-level 6.7-liter engine up to 370 hp and 850 lb-ft of torque.

As per the established trend, Cummins once more gave its newest engine a 5-or-so percent increase in power, adding 20 hp and 75 lb-ft of torque to the high output Aisin variant. This brought the total power output for the 2019 Aisin 6.7-liter up to 420 hp and an eye-watering 1,075 lb-ft of torque. The maximum horsepower was available from 2,800 RPM, and the torque from just 1,800 RPM, meaning that the RAM trucks would probably improve upon its towing capacity — again. And it did, with the 2024 RAM 3500 having a towing rating of 37,090 pounds and a payload of 6,560 pounds, both of which were figures that would have seemed impossible just a few years ago. 

This was officially the highest towing capacity ever offered on any RAM truck, ever; and the 3500 also had the biggest fuel tank in the class. Put all of this together and it's easy to see why RAM trucks are so beloved — and why its asking prices command such premiums. Additionally, Cummins finally listened to the community and swapped out the trouble-making Bosch CP4 fuel system with its much more durable CP3 unit, a move that happened in 2021 when the engine was updated.

And lastly, we have the most modern Cummins pickup truck engine so far: the 2025 6.7-liter Turbo Diesel for pickup truck applications. It currently boasts the same torque as the previous generation that it replaces, coming in at 1,075 lb-ft — still leading the class. However, horsepower has been increased slightly, as the engine is now rated for 430 hp. Cummins also announced that the company would be extending its already 35-year old partnership with RAM through 2030, so we will probably have a 40th anniversary special edition in 2029 — but don't quote us on that. 

The current engine is being offered on the RAM 2500 and 3500 models, as is tradition; and on the 3500, 4500, and 5500 chassis cab variants that we covered towards the beginning of this article. Gone also is the Allison transmission and the 68RFE, being replaced with a new TorqueFlite ZF eight-speed unit for 2025. That's it — there's not much more to be said. The 2025 6.7-liter unit is Cummins' most powerful one yet, has incremental advances in materials and design, and will probably get another power bump in 2027, after which a major change might come in 2029 to celebrate 40 years of association with RAM.