Vintage Dodge Ram diesel powered pickup trucks are grouped into Generation 1 and Generation 2 trucks with references to 12 valve and 24 valve versions of their Cummins B series engine. However, the powertrain evolution doesn’t directly align to body styles. In order to answer the question poised in the title of this article, we will need to unpack both story lines.
Body Styles and Platforms
Dodge introduced its first generation Ram platform in 1981 and continued to evolve and produce it until 1993. The truck had a timeless style featuring square headlamps, bracket mounted mirrors, a boxy cab, and dog dish wheel caps. Though the majority of these trucks shipped with gasoline power plants, in 1989 an optional 5.9 liter Cummins inline six diesel engine was introduced. This would become known as the infamous 12 valve Cummins B-Series.
In 1994 Dodge introduced its second generation Ram which featured a complete structural and aesthetic redesign. The commercial results boasted significant increases in sales and broad consumer applause. The aesthetics of this truck would carry over and influence the style of the truck into the 21st century. Still, the path to get there was not a simple one.
In 1986 Chrysler engaged an internal design studio to come up with the generation 2 design. The project was code named “Louisville Slugger”. Unfortunately their output more resembled a mini-van than a truck. It also lacked the physical capacity to house larger engines including the Cummins diesel platform. The design was deemed a failure and scrapped.
Chrysler pivoted on the “Louisville Slugger” failure by handing the project to its newly acquired AMC design studio. AMC delivered project “Phoenix” with a design worthy of a truck but it lacked originality when compared to similar designs by Ford and GM. In 1988, this design was also scrapped. For its 3rd attempt, the design teams shifted to design concepts inspired by WWII vehicles as well as big rig designs currently in the market. The third time was the charm and the result was what we refer to as the “Gen 2 Dodge Ram”.
Now that Dodge got the styling right, it is important to note that the second generation trucks continued to feature the 12 valve B-Series Cummins through 1998. Midyear through the 1998 year model, at the mercy of stricter emissions and efficiency regulations, the final 12 valves rolled off the assembly line. Their successor was basically the same engine featuring a different cylinder head and a new injection pump system. Though doubling the valves for a total of 24 was efficient, the fuel pump evolution proved to be problematic and was not well received by diehard diesel consumers.
Both generation 1 and generation 2 Ram platforms featured a variety of bed lengths, SWD/DWD configurations, and two door/four dour cab options.
Now that we have a basic understanding of the Gen 1 and Gen 2 body style evolution, let’s talk more in depth about diesel power plants.
5.9L Cummins B-Series Power Plant
The Cummins B-Series engine was produced from 1984 to 2007 in both inline four and six cylinder configurations. Since 1989 Dodge Ram trucks have featured two major generations of the 5.9 liter, inline six configuration–the BT and the ISB.
5.9 Liter 6BT
From 1989 to mid 1998, Dodge Ram’s diesel platform was a 12 valve, mechanically injected, 5.9L turbo diesel engine. At their peak, these engines produced 215 horsepower and 440 foot pounds of torque. Known for reliability, ease to work on, and mechanical injection pumps, this engine will go down in history as a favorite amongst owners.
What is important to note is that mechanical fuel pump on the 12 valve platforms differed from the first generation and second generation body style trucks. First generation 12 valves had what is known as a VE pump. The VE is a good pump; yet, had limited tuning options. The second generation 12 valves featured the Bosch P7100 which is considered the best mechanical fuel pump for reliability and performance tuning. P7100’s offer full a variety of opportunities to modify and tune just about every component in it.
12 valve powered Dodge Rams are still on the road today. Due to ease of modification and stout components, 12 valve engines are also popular in racing and sled pulls where they are dialed up to 800 horsepower and greater.
ISB 5.9 Liter
In mid 1998, Dodge incorporated a 24 valve version of the Cummins 5.9L platform. The primary driver for the change was meeting stricter emissions standards. In addition to doubling the number of valves in the cylinder head, the main difference in this new platform was that the switch from a completely mechanical injection pump (P7100) to a computer controlled mechanical injection pump called the Bosch VP44. Now, in addition to mechanically altering the injection pump for performance tuning, owners have computer related tuning options as well.
For the most part, the rest of the engine remained the same
Problems and Shortcomings
Since the 80’s Dodge Ram pickup trucks have been known for reliability; yet, like any automobile have had their problem list. For the most part, the Ram’s problems are easily solvable. The shortlist includes hood paint, dashboard quality, a faulty dowel pin, clutch plate durability in manual transmissions, and overall quality in automatic transmissions. From a platform perspective, there is no clear consensus as to whether a generation 1 or generation 2 Ram truck is superior. Where the discussion gets interesting is evaluating those generation 2 trucks that shipped with a P-Pump equipped 12 valve Cummins BT or a 24 valve ISB Cummins power plant. It is at this point that most Cummins enthusiast would start in with a statement about the superiority of the mighty 12 valve platform. Still, from a real world usage perspective both have pros, cons, and a problem list.
Which Dodge Ram is the Best?
In order to answer this question, it is crucial to understand who’s asking the question. Let’s break this down into a few personas.
The Power Hungry
When tuning any diesel engine you have to balance the goal of generating power with the limits of handling the power. The diesel platforms in both Generation 1 and Generation 2 trucks are equipped with rugged components that can handle power. Thus, it really comes down to generating power and the key component in that mix is the fuel pump.
If you are looking for a 5.9L Dodge Cummins for racing, sled pulling, or simply tuning for maximum power, a P-Pump equipped Second Generation Dodge Ram with a 12 valve engine is the clear winner.
Construction and Agriculture
If you use your Dodge Ram as a part of your livelihood, your primary need is likely reliability. With that said, stock 12 valve and 24 valve platforms do lack a few horsepower required for pulling large equipment or heavy loads. The clear choice for power and reliability is the 24 valve, manual transmission, generation 2 Dodge Ram. Here’s why.
Energizing and bullet proofing a 24 valve Cummins Dodge Ram is as easy as 4 steps. First, replace the uplifter pump with a FASS or Bully Dog system to ensure your VP44 doesn’t fail due to fuel starvation. Second, add an Edge Box to allow you to quickly manipulate injector pump timing via a sturdy 3 way switch. Third, install a basic 4″ turbo back exhaust system to free up exhaust flow. Last, replace the paper air filter with a drop in K&N filter to free up air intake (a new air box is not required). With these simple steps, you will easily add up to 65 hp and 180 foot pounds of torque while ensuring reliability for day in, day out work. Any mechanic can perform this work and you aren’t dependent on a specialized diesel tuner who is experienced in the ins and outs of a P-Pump.
If you are a collector or simply a Dodge Ram aficionado, you have a real decision to make. Outside of true collector factors including originality and condition, rarity is a driver. The Generation 1 production numbers are exponentially lower than their Generation 2 counterparts. This makes a Generation 1 truck attractive. However, there is a smaller population of pre ’98 1/2 Generation 2 trucks that shipped with 12 valve engines. Those Generation 2 Dodge Rams have both the design that inspired the future as well as an engine that is favorite amongst diesel fans. The choice is yours.
Unless you are a collector that is specifically looking for a first generation Dodge Ram Cummins 5.9L turbo diesel, the second generation Rams offer both the coveted 12 valve P-Pump power plant as well as the 24 valve edition. The answer to the question seems clear.