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What is the 3rd Gen Cummins?

The term “3rd Generation Cummins” refers to Dodge Cummins trucks with model years between 2003 and 2009. This generation of Dodge Cummins diesel trucks is one of the most desirable of all diesels because you can still get the 5.9L 24v Cummins engine but it’s paired with newer technology and bigger cabins. The most impressive 3rd Generation Cummins specs include the introduction of common rail technology, and the new Mega Cab configuration. The 6.7L Cummins engine is also made available later in this generation that is still used in today’s 4th gen and 5th gen Ram Diesel trucks. A full list of 3rd Gen Cummins Specs and detailed information about what makes this Dodge Cummins generation different than the others is found below.

3rd Generation 5.9L Cummins Performance Specs

When the 3rd Gen Cummins was released in 2003, the trucks made a huge leap in performance over Dodge Cummins trucks in 2002, even their high output models couldn’t compare. 2003 3rd generation Cummins trucks produce 305 horsepower and 555 lb-ft of torque. Thats a difference of 60 horsepower and 50 lb-ft of torque compared to the 2nd Gen high output model in 2002. Bigger horsepower and torque numbers aren’t the only 3rd Gen performance characteristics that improved. 3rd Gen Dodge Cummins trucks are also much quieter and much cleaner than they ever had been before.

High Pressure Common Rail Technology

The 3rd Generation Cummins marked a significant milestone for Ram trucks and Cummins. High pressure common rail fuel injection is introduced, making the trucks more efficient than previous generations. This high pressure common rail injection system is controlled electronically. An electronic lift pump sends fuel to the reliable CP3 injection pump. The CP3 fuel injection pump then pressurizes the fuel before it is sent to the fuel rail. The fuel rail then distributes fuel as it is called upon by the injectors. This system is much cleaner and more efficient than previous mechanical fuel injection strategies. It helped Cummins keep their trucks EGR-free for a couple more years, until they introduced the cleaner 6.7L Cummins engine in 2007.5.

5.9L 24V Fuel Upgrades

The new common rail system required other fuel upgrades to be added as well. The CP3 fuel injection pump was added to pressurize fuel before sending it off. CP3 injection pumps are well-known for being reliable and lasting a long time. New injectors were added that are controlled by the ECM. While these injectors weren’t as durable as previous mechanical versions, they still typically hold up for a couple hundred thousand miles. There are actually slight differences between the 3rd gen’s 5.9l Cummins injectors. Injectors on trucks built before 2004 have eight hole nozzles and spray at a 143 degree angle. 2004.5-2007 are modified to reduce emissions and only have 5-hole nozzles and they spray at a 124 degree angle.

3rd Gen Cummins Turbochargers in 5.9L Engines

Two different turbochargers were used on 5.9L variations of the 3rd Gen Cummins. In 2003, the Holset HE341CW turbocharger is introduced. This turbocharger has a mechanically controlled internal wastegate and it features a fixed geometry design. In 2004.5, a new turbocharger is introduced by Cummins. It helped the Dodge Cummins pickup line lower emissions, but it came with a noticeable performance boost too. This turbocharger is called the Holset HE351CW. It’s a fixed geometry turbocharger too, but unlike the HE341 its waste gate is controlled electronically.

3rd Generation 5.9L Cummins Specifications

3rd Generation 6.7L Cummins Specs

Cummins started from scratch and manufactured a new Cummins engine for 2007.5+ model year Ram pickup trucks. The change to a new motor was the result of increasing pressures to manufacture diesel trucks with lower emissions. Up to this point, Ram had done without an exhaust gas recirculation system on their diesel trucks. Starting in 2007.5 however, Dodge Cummins trucks would not only have an EGR, but also a diesel particulate filter system. These systems helped reduce overall emissions output tremendously, and they’re still used on newer versions of these trucks today. Unfortunately, emissions also cause more frequent problems due to clogging diesel particulate filters or EGR devices. Over time, these emissions devices have begun to be more reliable.

Performance Specs

The 6.7L Cummins offered better performance numbers and towing numbers than the previous 5.9L Cummins engine. To accomplish this, a new turbocharger was introduced and the fuel injection system was slightly modified. The engine itself is also very different than the previous 5.9l engine.

The Holset HE351VE Variable Geometry Turbo

The Cummins engine was the last to adopt variable geometry turbocharger technology. Ford’s 6.0L Powerstroke and GM’s LLY Duramax both already have been reaping the rewards of a vgt set-up. This turbocharger reduces emissions and improves drivability greatly. It also brings exhaust braking to the trucks. This exhaust brake or turbo brake feature improves stopping distance and can help dramatically increase brake life when used towing. The variable geometry turbocharger wasn’t without its issues however. Overtime it’s prone to sticking. By aggressive driving and regular use of the exhaust brake however, problems can be significantly reduced.

Fuel System Changes

The whole fuel system was changed to make room for more power. Thankfully, the CP3 injection pump is used again, but it allows for slightly higher injection pressure, up to 26,000 psi. The injectors were also redesigned. To accommodate increased fueling, all of the fuel rail, injection lines, and rail feed lines were enlarged up to 50%.

Engine Changes

The increased bore and stroke of the 6.7L Cummins engine resulted in a new for an improved block design. Cylinder pressures are drastically higher than the 5.9L Cummins engine. Cummins redesigned the cast-iron engine block, incorporating siamese cylinder bores. Very little changes were made to the cylinder head. Because of the increased cylinder pressures, it is much more common to have head gasket failures on a 6.7 than a 5.9l Cummins engine. Even so, head gasket failures are not a common occurrence on Cummins engines until driving hundreds of thousands of miles.

3rd Generation 6.7L Cummins Emissions

All 6.7L Cummins engines are outfitted with an EGR system and a DPF system. Auto manufacturers were being pressured to make trucks more environmentally friendly, and they succeeded. The exhaust gas recirculation systems and diesel particulate filter systems drastically removed the amount of emissions. The EGR focuses on removing NOx by reintroducing exhaust gases into the engine before being emitted out of the tailpipe. Diesel particulate filters act as a large filter that prevents soot from exiting the tailpipe. Black smoke isn’t seen from 6.7l Cummins tailpipes thanks to the DPF. When the diesel particulate filter accumulates a certain amount of soot, a regeneration occurs where the soot is burned from the filter. While emissions decreased, the devices are commonly linked to failures and lower fuel economy. It wasn’t until the introduced of SCR that an emissions device is introduced that can actually improve performance.

3rd Gen Cummins Horsepower/Torque Guide

3rd Gen Cummins Towing Capacity

3rd Generation Cummins towing specs vary according to truck configuration. If you want exact tow capacity, check out our Cummins tow Capacity guide. I’ll list the max tow capacity for both the 5.9L and 6.7L engines below. Make sure you check your owner’s manual before any towing to verify what your truck’s specific towing limitations are.

Max Towing for 5.9L Cummins Engines (Based on 2007 Model Year)

Max Towing for 3rd Gen 6.7L Cummins Engines

Other 3rd Generation Cummins Resources

Check out some of our other 3rd Generation Cummins resources by clicking on one of the links below.

• 9 Best 3rd Gen 5.9L Cummins Performance Upgrades
• 9 Best 3rd Gen 6.7L Cummins Performance Upgrades
• 11 Most Common 3rd Generation Cummins Problems