Getting Started Guide: Dodge Ram Cummins

Getting Started Guide: Dodge/Ram Cummins

For decades, Cummins diesel engines have been synonymous with power, durability, and performance, making them the engine of choice for heavy-duty Dodge Ram trucks. The Cummins engine was first introduced in the late 1980s to meet the growing demand for a powerful, reliable diesel engine that could handle towing, hauling, and commercial use. Over the years, the engine has evolved to meet stricter emissions standards while increasing power output and efficiency, becoming a favorite among diesel enthusiasts and workhorse owners alike.

Cummins engines are known for their inline-six design, which offers a more straightforward, robust structure compared to V8 diesels. This configuration makes Cummins engines not only durable but also easier to maintain and modify for power. Each generation of the 5.9L and 6.7L Cummins engines has its own unique characteristics, advantages, and challenges, and understanding these differences is key to maximizing performance, towing capacity, fuel efficiency, and long-term reliability.

From the early 12-valve 5.9L models that built Cummins’ reputation for durability to the modern 6.7L High Output models that deliver 1,000 lb-ft of torque, every generation has something unique to offer. However, choosing the right Cummins engine for your needs can be daunting with so many variations in power, emissions control systems, and compatibility with transmissions.

Additionally, the transmission paired with each Cummins engine plays a critical role in its performance, especially for truck owners looking to add horsepower and modify torque through aftermarket parts. The automatic and manual transmissions paired with these engines—ranging from the NV4500 to the modern Aisin AS69RC—can either enhance or limit your ability to push the engine’s capabilities.

This guide will help you navigate the strengths and weaknesses of each Cummins generation, from the 2nd Gen 5.9L to the 5th Gen 6.7L, along with key considerations for upgrading your transmission and boosting engine performance.

2nd Gen Cummins (1998.5-2002)

The 2nd Gen Cummins Engine introduced the 24-valve version of the 5.9L Cummins, replacing the 12-valve model from earlier generations. This update brought in the VP44 rotary injection pump, which added electronic control to the engine’s fueling system. While this added performance, it also introduced reliability concerns, particularly with the VP44 pump.

  • Transmission Pairing:
    • Paired with the NV4500 5-speed manual transmission for earlier models and the 47RE 4-speed automatic for automatic models. The NV4500 remains a popular choice for durability, while the 47RE is known to struggle under increased power loads without the Proper Upgrades.
  • Pros:
    • Increased Power: The 24-valve 5.9L offered more power than its predecessor, making it better suited for towing and heavy-duty applications.
    • Modifiability: The 5.9L Cummins remains a highly modifiable engine, with many aftermarket Performance Options available.
  • Cons:
    • VP44 Pump Failure: The VP44 injection pump is prone to failure, often leading to expensive repairs. It’s one of the most common weak points in this generation.
    • Transmission Issues: The 47RE automatic transmission is notorious for failure when subjected to increased power without reinforcement.
  • Boosting Power:

3rd Gen Cummins (2003-2009)

The 3rd Gen Cummins saw the introduction of the High-Pressure Common Rail (HPCR) fuel injection system, significantly improving fuel efficiency, performance, and emissions control. Early models still utilized the 5.9L Cummins, but in 2007, the larger 6.7L Cummins was introduced, bringing even more torque to the table, along with modern emissions control features like EGR and Diesel Particulate Filters (DPF).

  • Transmission Pairing:
    • The NV5600 6-speed manual transmission was mated to the 5.9L, and the 48RE automatic transmission replaced the earlier 47RE. The 68RFE automatic transmission debuted with the 6.7L Cummins, offering better gear ratios for towing but with some reliability concerns under high loads.
  • Pros:
    • HPCR System: The 5.9L with HPCR delivered improved fuel economy and smoother power delivery.
    • Increased Torque: The 6.7L Cummins brought even more power to Ram trucks, making it ideal for Heavy-Duty Towing and hauling.
  • Cons:
    • Emissions Equipment: The 6.7L Cummins introduced complex emissions control systems like EGR and DPF, which have been known to cause reliability issues if not properly maintained.
    • Transmission Durability: The 48RE automatic and 68RFE automatic can struggle with power upgrades without reinforcement.
  • Boosting Power:
    • For the 5.9L, performance mods like Tuning, Larger Injectors, and Turbo Upgrades are popular, while the 6.7L can be upgraded with EGR deletes and Turbo Enhancements. Be sure to reinforce the transmission to handle the extra torque if you’re pushing for serious power.

 

4th Gen Cummins (2010-2018)

The 4th Gen Cummins marked a significant upgrade with the 6.7L Cummins becoming the standard engine across all Ram HD trucks. This generation featured more power and torque, along with improved emissions systems like Selective Catalytic Reduction (SCR) and the use of Diesel Exhaust Fluid (DEF) to meet tighter emissions standards.

  • Transmission Pairing:
    • The 68RFE automatic transmission was standard on most models, while the Aisin AS69RC automatic transmission was available for 3500 models and offered better durability under extreme Towing conditions.
  • Pros:
    • Increased Power: The 6.7L Cummins in this generation produces up to 385 horsepower and 900 lb-ft of torque in High Output models.
    • Emissions Compliance: Advanced SCR and DEF systems made the 6.7L Cummins much cleaner without sacrificing performance.
  • Cons:
    • Maintenance: The increased complexity of the emissions systems, including the DPF, SCR, and DEF, can result in higher maintenance costs.
    • 68RFE Transmission: While stronger than previous automatic transmissions, the 68RFE still struggles under extreme conditions or when subjected to significant power increases.
  • Boosting Power:

5th Gen Cummins (2019-present)

The 5th Gen Cummins represents the pinnacle of modern diesel technology. The 6.7L Cummins engine in this generation delivers unprecedented power and efficiency, with High Output (HO) models offering up to 1,000 lb-ft of torque, making these trucks some of the most capable on the market for Towing and heavy-duty applications.

  • Transmission Pairing:
    • The 68RFE remains in standard models, while the Aisin AS69RC is paired with the High Output versions. Both can be Upgraded to offer the strength needed to handle the immense torque of the HO 6.7L Cummins.
  • Pros:
    • Best-in-Class Towing: High Output models offer 1,000 lb-ft of torque, allowing for best-in-class towing capacities of up to 37,090 lbs.
    • Advanced Emissions Systems: The SCR and DEF systems in this generation are highly effective at reducing emissions without sacrificing power.
  • Cons:
    • Complexity: The high-tech emissions systems, while effective, add complexity and can lead to higher maintenance costs over time.
  • Boosting Power:
    • The High Output 6.7L Cummins can handle extreme Power Upgrades, but if you plan to push past stock levels, the Aisin transmission will need Reinforcing. Popular mods include Turbo upgrades, Tuning, and Exhaust Modifications, but consider warranty implications when making modifications.

Each generation of Cummins engines offers unique strengths, from the simplicity of the early 5.9L models to the power and technology of the modern 6.7L engines. Understanding the transmission pairings, emissions systems, and performance potential of each generation will help you make the best choices for your build. At Alligator Performance, we have the parts and expertise to help you get the most out of your Cummins-powered Ram.