This cat's out of the bag

| January 03, 2006

The same reaction that oxidizes diesel fuel PM reduces engine oil PM to ash, which gathers in the DPF. “That has to be cleaned out,” Keene says. The EPA requires 150,000 miles between cleanings. Cat’s target is 300,000 miles. “It’s about two hours of shop labor, with the DPF either on or off the vehicle, once every two or three years,” Keene says.

The DPF weighs about 125 pounds and replaces the muffler. It will be used with different exhaust configurations, so Cat can’t say how it will affect a truck’s weight.

The sulfur issue is addressed primarily with low-sulfur fuel. “We had to get low-sulfur diesel fuel for this test drive,” Phelps says.

The weather was clear, dry and breezy. Keene had found some grades nearby steep enough to test the ’07 C-15′s power. The first grade was a mile-long, 3-to-4 percent grade on Peoria’s I-474 by-pass. Nodding to Illinois’ big truck speed limit, I set the cruise control at 60 mph at 1,270 rpm. I didn’t touch the throttle or gears. The C-15 held at 60 mph for the climb: neither lugged nor strained, but went stoically about its business. It’s my guess that if the hill had been 1,000 miles long, the C-15 would have maintained 60 mph at 1,270 rpm under the 77,000-pound load.

The scuttlebutt was that Cat’s ACERT engines perform well only at higher rpm for cruising and before shifting. To clarify this, I asked Keene if there was a certain engine speed at which the C-15 ran best. “Between 1,200 and 1,300,” he replied, adding, “I don’t like to run them above 1,500.”

After ascending the grade on I-274, we U-turned and headed back down. I engaged the engine brake and coasted in ninth gear. The C-15 once again performed well, slowing the rig below our 60 mph cruising speed, and I disengaged the brake before we obstructed traffic. The DPF seems to do a better job of quieting the C-15 than the old muffler, as even with engine brake on the exhaust was either inaudible or nearly so.

We drove back to I-74 and headed west. Between I-274 and exit 54 just east of Galesburg were two more grades much like the first: about a mile long, although the second was clearly steeper, a four percent grade. The C-15 climbed both hills without hesitation or strain while Keene, occupying the passenger seat, explained how Cat is already putting into place its service network for its ’07 engines. Before one upgrade I slowed to 55 mph and re-engaged the cruise control for the climb. The C-15 brought the 381/2-ton rig back up to 60 mph and 1,270 rpm up the hill.

For the drive back I chose U.S. 150 with its steeper hills, sharper curves and small towns: no place for cruise control, and I’d get an idea of the C-15′s performance in a non-interstate environment.

Observing the narrower, bumpier, two-lane road and cross traffic, I reduced cruising speed to 55 mph at about 1,225 rpm. The highway dipped steeply down and up through several ravines. Maintaining speed, I braked gently going down and dropped to eighth gear climbing, as I’d expect to with any engine. I started in second gear from each traffic stop, evaluating the C-15′s performance up through the gears, mindful to shift below 1,500 rpm. The engine smoothly brought the truck to speed each time, perhaps more quickly and easily than most engines: 550 horsepower and 1,850 pounds-feet of torque handling 77,000 pounds exactly as any driver would expect.

Phelps says a common complaint from fleets and OEMs after 2002 was that there was insufficient time to evaluate the engines before law required them to be used. “We responded to that by getting as many ’07 engines out to our customers over the summer, so they have 18 months with the engines before Jan. 1, 2007,” Phelps says. “They needed supplies of low-sulfur fuel,” Phelps says. “We helped them with that, too, although it was hard to get.”

Phelps says Cat benefits from this attention to detail. “It gives us more accurate return data,” he says. “We want to hear about our products from our customers.

So far, all return data has been good. “We’re getting all positive reports from fleets and OEMs,” Keene says.

Comments are closed. strives to maintain an open forum for reader opinions. Click here to read our comment policy.