Imagine walking out of your front door every morning and firing up a Dodge Ram stuffed with a 6.7L Cummins turbodiesel hooked to a six-speed Aisin automatic transmission. This diesel fantasy will become reality for those lucky enough to choose the all-new '07 Dodge Ram 3500 Chassis Cab as their workhorse this fall. Our sources tell us that you should also expect Ram 4500 and Ram 5500 Chassis Cab models to be released in the near future as well.
Engine
While the 6.7L engine shares DNA with the current oil-burner found in Rams on the streets, it's a very different animal. Even with the bigger displacement, it's rated at 305 hp at 3,000 rpm and 610 lb-ft of torque at 1,600 rpm. Huh? It's bigger by 49 cubic inches but makes less horsepower and the torque has not increased? Welcome to the world of '07 emissions standards.
It's reasonable to assume the larger displacement combined with lower compression ratio and "detuned" power ratings will help keep exhaust gas temperature (EGT) low, especially since the Cummins will be saddled with a new exhaust gas recirculation (EGR) system. That's not all; the 6.7L will have a self-cleaning diesel particulate filter, which will need a relatively cool baseline EGT when it decides to burn extra fuel to help ignite the bits that have been trapped. An oxidation catalytic converter will also be part of the new emissions system.
The turbo on the 6.7L Cummins will feature a water-cooled center section and variable geometry, thanks to an electronically controlled sliding plate (as opposed to fragile adjustable vanes). This will provide more control of the boost fed to the engine, which should result in less turbo lag and more predictable performance. Another benefit of the new turbo setup will be an optional factory exhaust brake that Dodge says will work better than current aftermarket units.
Transmissions And Transfer Case
The optional Aisin-Seiki AS68RC six-speed automatic transmission with two Overdrives will make its debut behind the Cummins engine. This new slushbox has a 0.63:1 top gear that can be locked out and an electronically controlled multi-disc converter clutch. It comes with a standard power-take-off (PTO) mounted on the passenger side to harness your diesel power and drive a variety of commercial tools. Aisin Seiki isn't a newcomer to the transmission business. It has designed and built gearboxes for everything from Land Cruisers to Cadillacs and hybrids. It's rumored that this same transmission could be used in an upcoming Toyota 3/4-ton truck, as well.
The familiar manual six-speed Overdrive G56 transmission will still be standard equipment behind the diesel. It also comes with a PTO provision that can be tapped into on either side of your rig.
Four-wheel-drive trucks will come with the familiar transfer cases found in the current Heavy Duty Rams. The NV 271 is manually controlled with a lever, while the NV 273 is electronically activated. Both transfer cases are part-time units with a 2.72:1 Low-range ratio.
Axles And Frame
The new 3500 Chassis Cab will come in two lengths: 60 inches from cab to axle and 84 inches. Only the 60-incher will be available in a single-rear-wheel configuration and boasts the highest single rear wheel (SRW) Gross Vehicle Weight Rating in its class at 10,200 pounds. Dualies will be able to support a GVWR of 12,500 pounds. The manual transmission can be equipped with a 3.73 or 4.10 axle ratio, but the automatic-equipped trucks will only come with a 4.10.