By G.R. Whale
Dodge first stuffed a Cummins medium-duty engine into a light-duty truck, the D/W series Ram, 15 years ago. As the years went by, power went up, so much so that the current Ram Cummins has more than twice the rated horsepower of the original D/W. The new Cummins delivers 325 horsepower at 2900 rpm and a nice round 600 pound-feet of torque at 1600, without any fine print: It's not a high-output option, doesn't have a transmission restriction or de-rating, and is 50-state legal.
Although the engine upgrades were driven by calendar-year 2004 emission standards, there's more to it than being a different engine. While you may wonder how it made the automatic transmission handle the power, the 48RE introduced last year was designed with this input in mind (and the NV5600 six-speed was good for it as well), so the gearboxes didn't require any changes. Software programming was changed on the automatic, which can now lock the converter under certain circumstances in fourth, third, or second, and is fully compatible with the Mopar exhaust brake. The automatic's only deficiency is the lack of a fifth gear, which can be found in competing trucks.
Cummins 600
The Cummins ISB motor used in other markets has made these power levels before, but not, as the Cummins rep put it, "at these grams-per-mile," referring to emissions. The basic block and self-priming common-rail fuel system have been retained.
Hardware changes include a spur-gear front geartrain for reduced NVH, a new exhaust manifold (with two-stage gasketing), a larger compressor within the same HX35 housing, an electronically controlled wastegate (to get the benefits of variable geometry without the complexity), and a controller with about 50-percent-more code in it. An EGR system isn't necessary, which saved roughly 50 part numbers and a lot of plumbing.