Test drive: ’07 Detroit Diesel Series 60

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PORTLAND, Ore. – When Detroit Diesel rolled out its first EGR engines in 2002, the company had racked up a paltry 2.8 million test miles – 2.3 million of which were on a dynamometer. Not a single engine was placed with a fleet for real-world testing, the company admits.

Fast-forward to February, 2006. Detroit Diesel and Freightliner have already completed more than 5.2 million test miles on the Series 60 engine – well ahead of schedule to complete 14.8 million miles of testing before the ’07 engines are rolled out in January. About 6.7 million of those miles are being racked up on customer vehicles in real-world operating environments.

“It’s a big difference in terms of being ready,” admits Tim Tindall, director of the Series 60 2007 program for Detroit Diesel Corporation. “We’re far, far better off and will have a far improved launch over previous emissions levels.”

Including the MBE 4000 and MBE 900, about 24 million test miles will be completed before rollout, Tindall said.

“Our test program for EPA ’07 is the most comprehensive in our history,” he added.

Detroit Diesel officials say the company began preparing for the 2007 EPA emissions standards as far back as 2003, and was prepared for the introduction of the ’07 engines a full year before launch.

As with most other manufacturers, Detroit Diesel is increasing its use of EGR to further reduce NOx while also employing a diesel particulate filter (DPF) to trap and burn off particulate matter. With the 2007 trucks and engines performing well in the field, Detroit Diesel and Freightliner recently had the confidence to invite a group of trade press editors for a test drive in Portland, Ore. Event organizers mapped out a run from Freightliner’s wind tunnel facility in Portland, up US-26 to an old logging camp turned restaurant, known as Camp 18.

The 63 mile run included some hills that were significant enough to give the ’07 Series 60 Detroit Diesel engine a bit of a workout. Freightliner engineer George Myers and I were making the trip in a Century Class 120 with a Meritor transmission and 455 hp under the hood.

The trucks involved on the test drive included an assortment of customer vehicles as well as dedicated test trucks that are on the roads around Portland for two 10-hour shifts each day. As we negotiated our way onto the highway, there was no noticeable difference between the ’07 engine we were driving and its present-day predecessors – and that’s a good thing. Engineers have strived to make the new generation of engines perform like the powerplants drivers are accustomed to operating.

The DPF, mounted inconspicuously underneath the chassis, is designed to trap soot and burn it off using extremly high temperatures. This process is known as regeneration, and there are two types: active and passive.

Passive regeneration occurs when the engine produces enough heat to allow the DPF to reach temperatures sufficient to burn off the soot – about 600 C is required. When these temperatures cannot be attained by the DPF (when hauling light loads or operating in extremely cold climates), it needs some help to regenerate. This help comes in the form of a shot of diesel fuel that causes temperatures to increase to the point where regeneration is possible.

Because an active regeneration can use up to a gallon of diesel, ideally the DPF will be able to regenerate passively most of the time. As we climbed a long uphill grade just outside Portland, Myers explained it would be an ideal time for a passive regeneration to take place.

However, Freightliner engineers had tricked the engine into thinking an active regeneration was required so we could experience one first-hand. With the engine programmed for an active regeneration, I paid close attention to anything that would suggest the regeneration process was taking place. However, I heard nothing, felt nothing and saw nothing. That’s just the way it should be, confirmed Myers.

“It’s been doing it the whole time we’ve been going up this hill,” he said. “You just don’t notice it.”

During an active regeneration, the DPF is continuously fueled. Regeneration can take between 20 and 30 minutes to complete and the process occurs about once every 850 miles or so.

As far as the ’07 tractors are concerned, you’d need a keen eye to notice any significant changes between the trucks we were test driving and current models. The cooling system has been increased with a larger radiator the most noticeable difference. The Century Class we were driving featured a 1,625-inch rad to provide increased cooling capabilities.

The end result is that less fan-on time is required, said Myers, adding it takes up to 40 hp to power the fan so reducing fan-on time also saves fuel.There have also been some minor modifications to the frame to accommodate the DPF – but beyond that, the ’07 tractors will look and drive much like today’s models.

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