It has been a full year since the March '05 announcement of the Dodge 3500 Chassis Cab with the 6.7 liter Cummins engine. The 3500 Chassis Cabs rolled off the assembly line last fall and we introduced this column in the magazine to cover developments with the 6.7 HCPR engine.

At the Chicago Auto Show in February Dodge announced their new 4500 and 5500 Chassis Cab that use the same 6.7 HPCR engine. Hand-in-hand was the '07.5 model year introduction of the 6.7 HPCR engine in the 2500 and 3500 pickup trucks.

Somewhat lost in the flurry of announcements, introductions and hardware hitting the streets was the following press release from Cummins.

"In January Cummins Inc. unveiled the strongest, cleanest, quietest best-in-class 2007 6.7-liter Turbo Diesel engine, used exclusively in Dodge Ram 2500 and 3500 Heavy Duty pickup trucks. The engine has increased displacement providing increased horsepower and torque while achieving the world's lowest 2010 Environmental Protection Agency (EPA) NOx standard a full three years ahead of the requirements.

"Cummins is the first diesel engine manufacturer to have a product certified to the 2010 EPA heavy-duty engine standards for oxides of nitrogen (NOx) and particulate matter (PM) emissions, making it the cleanest heavy-duty diesel engine available in North America. The 2010 EPA standards for NOx (0.2g) and PM (0.01g) represent a more than 90 percent reduction in each pollutant, compared to the 2004 standards.

"'The application of the right technology on the Dodge Ram is an extension of the joint clean diesel development work Cummins and DaimlerChrysler have performed together for nearly two decades,' said Cummins President and Chief Operating Officer Joe Loughrey. 'The new best-in-class Cummins Turbo Diesel and the Dodge Ram will provide the strongest, cleanest, quietest solution for heavy-duty pickup truck customers.'

"'This new technology is a significant validation of the industry's ability to meet the EPA's 2010 clean diesel standards. These innovations help power our economy and drive our environmental successes,' said Bill Wehrum, EPA's Acting Assistant Administrator for Air and Radiation."

Cummins, in conjunction with DaimlerChrysler and the EPA, made this announcement prior to the Washington DC Auto Show in January.

When I first read the press release my reaction was, "Ho, hum, another beat-the-chest exercise by the PR folks." Is your reaction the same?

Look at the release again. It is important to note that with the 6.7 HPCR engine Cummins is the first diesel engine manufacturer to meet the 2010 EPA standards. This is big news!

Let's say it again, the 6.7 HPCR engine meets the 2010 EPA standards.

So, unlike the yo-yo changes that we have had to endure every 3 to 4 years, the '07 HPCR will be good until the next set of emissions legislation in 2013.

Will Ford be able to offer an engine package like this?

Will GM be able to offer an engine package like this?

Additionally, consider that the 2010 6.7 HPCR engine offers a solid engine platform that allows Dodge to engineer the next generation Ram, thus keeping the Dodge/Cummins relationship stable.

2010 Technology

This is big news. So much so that the February '07 issue of Diesel Progress (a trade-only publication, not to be confused with the plethora of newsstand "glossy" publications) devoted five pages to the 6.7 HPCR and its technology. The following are excerpts from the Diesel Progress article by Mike Brezonick as he talks with several of the Cummins Inc. personnel behind the 6.7 HPCR project.

"When Dodge and Cummins announced the 2007 engine months ago, both companies highlighted some of the notable and apparent changes. Yet both companies kept very quiet on what is in some ways the most noteworthy aspect of all, choosing to save that for a more appropriate stage.

"That stage turned out to be the Washington Automobile Show in January. Cummins took the wraps off emissions technology that is being used on the 2007 model year Ram 2500 and 3500 Heavy Duty pickup trucks. The system, which Dodge and Cummins said will meet EPA's emissions regulations for the next six years, is unprecedented in its sophistication and includes what is considered to be the first commercially produced NOx adsorber system to be used on a production vehicle in any market segment in North America.

The Challenge and Relationships

"'As we looked ahead to '07, Dodge's challenge to us was to stay up with the competition in the horsepower and torque wars,' said Jeff Caldwell, Cummins executive director – DaimlerChrysler Business. 'Our challenge was how do we do that and meet emissions?

"'Beyond cooled EGR and variable geometry turbos we knew we were going to add aftertreatment and if we took the same path that everyone else was taking, it would drive some pretty significant changes to the cooling system. You've seen that in the 2007/2008 model year trucks from Dodge's competition—they're wider and taller. They've changed the trucks.

"'We feel terrifically about our relationship with DaimlerChrysler,' said Joe Loughrey, Cummins' president and chief operating officer. 'And the decision to use this particular recipe to meet the 2010 standards in 2007 was a collective decision between Cummins and DaimlerChrysler after having reviewed more than one alternative as to what our approach might be.

"'I have to emphasize that this was not Cummins walking in to say, hey, here's the deal. It was us working very closely with DaimlerChrysler and our partners and determining this was the best by far course of action to make the best truck for customers and the cleanest truck you can find anywhere in America.'

The Technologies

"Clearly, the most head-turning part of the vehicle is the addition of the NOx adsorber to the aftertreatment system. For the better part of a decade, NOx adsorbers have been cited as a promising technology for controlling NOx emissions from diesel engines—indeed, they were specifically cited as key technology by EPA in its rulemaking.

"A NOx adsorber resembles a conventional catalyst, incorporating a catalytic substrate through which diesel exhaust is directed. Then the NOx molecules are collected and held—"adsorbed"—onto the surface of the substrate, removing them from the exhaust stream. When the surface area of the substrate is full, the adsorber is regenerated with heat used to chemically change the NOx into more benign gases, mostly nitrogen and oxygen.

"However, for all their potential in principle and in the lab, NOx adsorbers remained closer to a promise than a real product. More on the NOx adsorber in a minute.

"Cummins incorporated a range of technologies into the engine. A variable geometry turbocharger from Cummins Turbo Technologies contributes to improved engine breathing. And, because of the robustness of the sliding vane design, it also can be used to provide engine braking, a beneficial feature, particularly in towing applications.

"Other changes to the engine include an intake throttle between the engine and charge-air cooler and a bypass valve in the EGR circuit that allows the gas flow to bypass the EGR cooler entirely in some operating conditions. This allows for more precise control of EGR rates, faster engine and vehicle warm-up and can also assist in raising exhaust temperatures for aftertreatment regeneration.

"The engine also has a closed crankcase ventilation system developed by Cummins filtration. The system incorporates a coalescing filter that captures oil mist and returns it to the crankcase. The filter requires service after approximately 60,000 miles.

The Aftertreatment System

"The Aftertreatment system is a three-section unit that is packaged mostly under the vehicle floor. It begins with a close-coupled catalyst—essentially a conventional diesel oxidation catalyst incorporating a metallic substrate—mounted to a short downpipe just off the back of the turbocharger. Shortly behind and below the close-coupled catalyst is the NOx adsorber unit, which is followed by a particulate filter. Both the NOx adsorber and PM filter use ceramic substrates.

"All three aftertreatment sections have their own active regeneration schedules, and the engine ECM controls the regeneration cycles. Even more significant, despite the use of fuel for regeneration, the overall fuel economy for the vehicle is virtually unchanged from the 2006 trucks, Cummins said.

"The NOx adsorber is regenerated every few minutes at approximately 600° to 800°F and the process takes about three to five seconds. The NOx adsorber will also, over time, absorb sulfur from the fuel, which can reduce its effectiveness over time. So depending on how much fuel is burned—typically every two tankfuls, a separate regeneration cycle is initiated to remove the sulfur. The PM filter is regenerated when mass flow sensors in the exhaust system detect a specified amount of loading on the substrate, typically about every four operating hours. Unlike the PM filter systems used on heavy-duty applications, there is no ash cleaning required, and the PM filter—like the NOx adsorber and close-coupled catalyst—is rated for the life of the vehicle.

"In another departure from the heavy-duty side, all of the hydrocarbon dosing (diesel fuel) needed to raise the temperature for the various aftertreatment regenerations is handled by the fuel injection system rather than a separate injection system.

"'It took some time and a lot of work to integrate the control system,' said Jim Fier, technical project leader. 'Some of the fuel we use to light the catalyst is partially burned, and any time you burn fuel, you produce power. If we didn't you would feel that extra fuel as power. With both the air handling and the fueling, we had to adjust those various pulses in order to keep the power balance and the torque balance as we go in and do the regenerations.'

"Cummins engineered the entire aftertreatment system down to specifying the washcoat on the catalyst bricks, and the system was assembled by Tenneco, which does aftertreatment system packaging for many segments of DaimlerChrysler."

At the onset I noted that the news about 2010 emissions and the 6.7 HPCR engine was noteworthy. The Diesel Progress article excerpts give us a better understanding of the technology behind the engine. Go forth and be proud of the Dodge/Cummins truck that you own.