The 6.7L Cummins engine makes...
The 6.7L Cummins engine makes its debut in the '07 Dodge Ram 3500 Chassis Cab. To meet the government's strict new emissions regulations, the engine uses a larger displacement, a bigger EGR system, a passive catalytic converter, and a soot-trapping diesel particulate filter that communicates with the engine computer.
'07 Dodge Ram 3500 Chassis Cab
What's a Chassis Cab?
Right now, there's only one vehicle available to the general public that's equipped with the new 6.7L Cummins turbodiesel engine: the '07 Dodge Ram 3500 Chassis Cab, which does not come with a standard pickup bed. Instead, it comes with a unique frame behind the cab that includes flat rails designed to accept everything from a U-Haul-style box to a stake bed, like the one we tested.
In the near future, this 6.7L Cummins engine will be under the hood of every new Ram 2500/3500 diesel you'll find on dealer lots. We had to know what it's like to live in a world constrained by '07 EPA emissions rules, so we put the Chassis Cab to work with the relatively light-duty task of moving furniture. We added more than 1,000 miles to the odometer and took the truck from Los Angeles to San Francisco and back with pit stops in Bakersfield and Sacramento. This trip involves various terrains including the steep inclines and declines of the famous Grapevine route through the Tejon Pass (elevation 4,144 feet) in the Tehachapi Mountains, flatland cruising on Interstate 5 through Central California, and gridlock traffic in both San Francisco and L.A.; a good mix to give us a feel for the new emissions equipment-laden engine and the six-speed transmission that's made in Japan.
 Although Anton and Emma had...  Although Anton and Emma had a blast playing around in the Knapheide stake bed, the average consumer will have no use for this industrial add-on that requires "driving by mirrors." The Ram Chassis Cab is prepared to accept everything from a moving van-style box to a flatbed like this one. Do you need a Chassis Cab pickup? If you have to ask, then the answer is probably "no." |  The 6.7L Cummins is basically...  The 6.7L Cummins is basically a bored-and-stroked 24-valve 5.9L Cummins with a variable geometry turbo and new emissions equipment. The large silver rectangular device on the passenger side of the engine is the new giant exhaust gas recirculation cooler. Its output is routed through the line insulated with black mesh and into the intake manifold on the driver side of the engine. |  This tag indicates the Ram...  This tag indicates the Ram Chassis Cab left the DaimlerChrysler factory in a condition not ready for public roads. Trucks like this one are only sold to approved "upfitter" companies that attach whichever type of bed is ordered. |
6.7L Cummins Turbodiesel
To help meet the strict new '07 EPA emissions requirements without losing power, Dodge and Cummins needed to reduce emissions of nitrogen oxides and soot. The diesel particulate filter and the use of low-ash oil take care of the soot, but reducing nitrogen oxides requires cooler combustion temperatures. One way to help achieve this is to increase the displacement of the engine, hence the bump from 5.9L to 6.7L-which means the engine does not have to work as hard to produce about the same amount of power as the previous model. The new engine feels just as strong as the 5.9L it replaced, which is impressive since it's saddled with new emissions equipment while only having a displacement that's increased by less than what you get in a 1-liter bottle of Coke. We made a trip to Los Angeles Performance Division for some time on their dyno and came away with peak ratings of 260 hp and 509 lb-ft of torque at the rear wheels (see chart on page 126 for the power curves). We think the new turbo (described later in the article) plays a big role in keeping the engine perky, but the new transmission also deserves some credit.