In 2007, Cummins introduced a new engine for the Ram pickup truck lineup, changing the game for diesel trucks. The need for lower emissions on diesel trucks had been increasing, and Ram had been without an exhaust gas recirculation (EGR) system on their diesel trucks up to that point. The new Cummins engine included both an EGR and a diesel particulate filter system, which helped to reduce emissions output significantly. These systems are still in use on newer versions of Ram trucks today.
The Cummins engine was the last to adopt variable geometry turbocharger technology, which reduces emissions and improves drivability, and brings exhaust braking to the trucks. Over time, the turbocharger is prone to sticking, but aggressive driving and regular use of the exhaust brake can significantly reduce these problems.
The 6.7L Cummins engine is now outfitted with both an EGR system and a DPF system. These devices drastically reduced the amount of emissions that were previously being produced, which was in line with the pressure that auto manufacturers were under to make trucks more environmentally friendly. The EGR focuses on removing NOx by reintroducing exhaust gases into the engine before being emitted out of the tailpipe, while the diesel particulate filter acts as a large filter that prevents soot from exiting the tailpipe. When the 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 introduction of SCR that an emissions device was introduced that could actually improve performance.
With more stringent federal particulate matter emission regulations looming, Cummins had been developing a new diesel engine for Chrysler’s Ram line, which debuted in 2007.5. This new engine boasted more displacement, more horsepower and more torque than the 5.9L Cummins, making use of a variable geometry turbocharger, a factory-integrated engine exhaust brake, and a higher-pressure Bosch common-rail injection system. The 6.7L inline-six engine produced 350 hp and 650 lb-ft of torque, keeping it competitive with the GM and Ford offerings at the time and becoming the cleanest-burning Cummins engine to ever power a Dodge Ram.
Replacing the 5.9L Cummins with the all-new 6.7L displacement version was a significant change in the ’07.5-’09 heavy-duty Rams. This change was due to stricter emission regulations taking effect, and marked the beginning of acronyms such as EGR, DPF, and NOx catalyst becoming everyday nomenclature associated with Dodge’s diesel powertrains. A brand-new automatic transmission was also introduced behind the 6.7L Cummins, allowing Ram HD’s to keep pace with the advanced auto transmission technology the competition was offering.