1st Gen 5.7 L 12V Cummins Specs, History and Tow Capacity

The driveability of the engine is a big part of the setup. If you can’t squeeze the gas down, you can’t go anywhere - Michael Waltrip 

Anyone who has ever sat behind the wheel of a pick-up truck knows that there’s nothing quite as sweet or intoxicating as the sound of a diesel engine firing up.

Hearing that roar and feeling the way the motor throbs through the steering wheel practically beginning you to stamp down hard on the gas pedal and take off like a bat out of hell is something that you don’t forget in a hurry. 

The truth is, most of us never forget it and as soon as we’ve had our first taste of that power, we want more. It’s easy to get hooked on the diesel life and almost impossible to leave it behind once it gets in your veins. 

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The diesel world has its own rules and regulations, a strict code that it follows, and its own history and mythology. And its history was forever altered by the motor that changed everything, and continues to this day to be worshipped by, and talked about in hushed reverential tones by diesel enthusiasts everywhere.

That motor is, of course, the first generation five-point nine-liter twelve-valve Cummins.  It might be more than three decades since it was first unleashed, but in all that time, there hasn’t been a single challenger that can lay claim to the crown that Cummins rightfully won when they designed, developed, and manufactured that motor. 

Cummins And Dodge - The History Of The First Generation Five Point Nine Liter Twelve Valve Beast.

Despite being a dominant force in the muscle car world of the sixties and early seventies, by the end of the nineteen-eighties  Dodge was all but a spent force. The cars that Americans drove and what they wanted from an automobile had changed drastically during the previous two decades and Dodge was being beaten on all fronts by General Motors and Ford.

And the one area of the market where they were feeling the pain of being thrashed time and time again more than any other was in truck manufacture. It didn’t matter what Dodge tried to do, year in and year out their main competitor’s diesel trucks managed to outperform them in almost every field.

They had better fuel economy, generated more torque and towing power, and were generally more reliable. That all changed when Dodge teamed up with Cummins in nineteen eighty-nine and started using their motors in their trucks. 

That infamous first-generation Cummins motor that Dodge used was the five-point nine, twelve-valve diesel motor and it was unlike anything that any truck owner had ever seen or driven before.

It was so successful that Dodge would use it to power their trucks for the next four years and from nineteen eighty-nine to nineteen ninety-three, the first generation Cummins was the motor of choice in every single two-fifty and three fifty D/W that Dodge made. 

It was the beginning of a beautiful partnership that is still in place thirty years later, as Cummins motors are still being used to power RAM trucks. And as more than a few industry insiders and big wigs have sagely pointed out in the last three decades if it wasn’t for Cummins, RAM wouldn’t exist. Dodge trucks owe everything to that first generation motor.

What Was It About The Motor That Made It So Great?

Honestly, it was everything. Sometimes a company just gets everything right, and that’s what happened with the first generation five pint nine Cummins motor. Primarily designed for the agricultural and commercial markets, it was made to be reliable and to everything that farmers and long-distance and delivery drivers needed a motor to do.

In fact, it was so reliable, a lot of the first generation D/W trucks that it was fitted in are still running and changing hands to this day. They may be getting increasingly rare, but they’re still out there, they’re still running, and for a certain sector of the truck driving world, they’re the diesel equivalent of gold dust. 

Simplicity And Reliability Go Hand In Hand

One of the main reasons why the motor was so reliable was due to its design. Because it was made for the agricultural and commercial markets, it had to be easy to work on and maintain, so Cummins chose to use an inline configuration rather than a more powerful “V” design, which left more room in the engine bays and compartments that it was fitted in, which in turn gave the amateur and professional mechanics responsible for its upkeep more room to work on it. 

And because Cummins opted for the inline design, the motor had fewer moving parts than its more powerful V-shaped cousin, which again made it more reliable, as the fewer parts that a motor has, the less there is that can go wrong with it. 

The other crucial factor that helped to forge Cummins’s incredible reputation for reliability, was history. During the time the motor was in production, emission regulations were nowhere near as stringent as they are today, so they didn’t have to conform to the regulations that modern engines do and weren’t controlled by the same kind of computer management systems that modern motors rely on to govern their emissions. 

And even though those engine management systems are created with the best of intentions and to save the future from being destroyed by diesel particulates, they’re increasingly complex. The problem with using complex systems is that the more complex they are, the more there is that can and does go wrong with them. 

The first generation Cummins was different. It was just a heavy-duty diesel motor that was designed and engineered to do what it did as simply and effectively as possible. Remember when your granddaddy used to say that things were more straightforward and better in the old days? He was right, they really were. 

The First Generation Diesel Firsts

One of the main reasons that the first generation Cummins motor achieved the level of notoriety that it did, was because it was the first commercially available diesel motor to utilize and incorporate direct fuel injection and forced air induction, or as its more commonly known, a turbocharger, in its design.

Direct fuel injection makes a motor more efficient by forcing fuel directly into the combustion chamber of the engine, which increases combustion efficiency, which in turn makes the reaction that the motor uses more efficient, which results in more power being produced by the motor and that extra power translates to more miles from a tank of diesel. 

If you want a truck to appeal to the average working stiff, the best way to do it is by targeting the one thing that matters most to blue-collar America, making each dollar stretch further, and thanks to direct fuel injection, more miles per tank ensured that each diesel dollar spent got Dodge drivers a little further down the road.

The second of the firsts that Cummins used in the design of their motor was the addition of a turbocharger. It was the first time that one had been fitted to the motor that a commercially available diesel truck used and it had a staggering effect on the amount of power that the D/W two-fifty and three fifty generated and exponentially increased both their towing and hauling capacity.

And Cummins did it by using something that, in engineering terms at least, was, and is a relatively simple idea. Turbochargers channel the waste gases that motors produce back into the motor, which greatly enhances the amount of compressed air being forced into the combustion chamber, and coupled with the direct fuel injection system, it made the Cummins one of the most powerful motors that had ever been fitted to a pick-up truck. 

But they didn’t stop there and in nineteen ninety-one Cummins upgraded their first-generation motor by adding an intercooler. Another mechanically straightforward idea, intercoolers are used in conjunction with turbochargers to lower the temperature of the hot air that turbos create before it’s forced into the combustion chamber of the motor.

Colder air is denser than hot air is, and that extra density makes the combustion reaction even more efficient than it already is, and that extra efficiency that the intercooler created meant that the D/W’s fuel economy and power levels increased, further cementing the Cummins already formidable reputation. 

The Cummins Way - Towing Power, Torque And Specs

If we’re going to talk about the first generation five-point nine-liter twelve-valve Cummins motors, we have to talk about the things that made it really special.

Because of the increased power that the addition of the turbocharger and direct fuel injection created, the first generation five point nine Cummins motor generated four hundred pounds per foot of torque at around one thousand seven hundred rpm (revolutions per minute), which not only increased the acceleration of the D/W truck it was fitted in, it also vastly increased their towing power. 

The standard D/W trucks that Dodge made at the time came with three transmission options, a three-speed automatic, a four-speed automatic with overdrive, and the big kahuna, the five-speed manual with overdrive, or Getrag 360 as it’s known among the diesel faithful. The Getrag 360, was the transmission that helped to establish the phenomenal towing reputation of the Cummins.

It was, and still is an incredible piece of engineering, and paired with the mind-blowing torque that the Cummins produced, meant that the Dodge trucks that were fitted with it could tow eleven thousand nine hundred pounds of weight and haul around ten thousand pounds worth of whatever you wanted to throw in the back in their beds. 

While it may not seem like a lot in the dizzying world of speed and power that’s made at the rear wheel today, especially given the size of the motor, the Cummins was capable of producing one hundred and sixty horsepower at two and half thousand revolutions per minute.

Even thirty years ago, the Cummins was never going to break any land speed records, but it was never designed to. It was engineered to be powerful and efficient and to outclass and leave Dodge’s competitors choking in its fumes. And that’s exactly what it did. 

The First Generation 5.9 Liter Twelve Valve Cummins Legacy  

When Cummins partnered with Dodge at the tail end of the eighties to furnish their trucks with a new diesel motor, they forever altered the course of the industry.

The first generation five-point nine-liter motor was a game-changer and as well as revolutionizing the way diesel motors were, and are, used in trucks and cars, it helped to forge a partnership that’s lasted the course and more than thirty years later is still going strong. 

RAM may have spread their wings and left the Dodge nest to find their own path and in doing so become one of America’s premier truck brands, but they’re still powered by Cummins motors. And they’re still as reliable and powerful as they were when the legendary first-generation motor found it’s rightful place under the hood of a Dodge.