ACERTainty for 2007

Cat’s 2007 C15 engine will go into production no later than Jan. 1, 2007.

After a lecture and tour at Caterpillar’s plant near Peoria, Ill., it was time to quit talking and start driving. The test at hand represented Cat’s future in the heavy-duty diesel market – a 550-horsepower C15 engineered to meet the 2007 emissions standards.

I was introduced to a 2000 Kenworth T2000 packing a C15 making 1850 lb.-ft. of torque at about 1,200 rpm, a nine-speed Eaton-Fuller transmission, 3.25 rears and 22.5 LP tires. Hooked to a loaded 53-foot dry van, the rig had a gross weight of 76,800 pounds.

Immediately noticeable, mounted just aft of the passenger door, was the 125-pound diesel particulate filter. It enables the new engines to cut particulate to the U.S. Environmental Protection Agency mandate of 0.01 grams per braking horsepower. The exhaust stacks were not new, but after I rubbed a finger inside one, it came out clean – a sign that the DPF is indeed doing its job.

The DPF, which will also be on competitive 2007 engines using exhaust gas recirculation, isn’t the only change for Cat since it introduced ACERT technology with its 2002 engines. The engines also feature an enhanced combustion process called clean gas induction and a closed crankcase ventilation system.

Our first climb was a mile-long, 3 percent to 4 percent grade on Peoria’s I-474 bypass. I set the cruise at 60 mph at 1,270 rpm. I didn’t touch the throttle or gears. The C15 held at 60 mph for the climb. It neither lugged nor strained.

I had heard that Caterpillar’s ACERT engines perform well only at higher rpms for cruising and before shifting, but this apparently isn’t true.

The C15 runs best between 1,200 and 1,300, says Caterpillar’s customer value manager, Robert Keene. “I don’t like to run them above 1,500,” he says.

After ascending the grade, we U-turned and headed back down. I engaged the engine brake and coasted in ninth gear. The C15 slowed the rig below our 60 mph cruising speed. The new DPF seems to do a better job than the old muffler of quieting the engine. Even with the engine brake on, the exhaust was virtually inaudible.

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Heading west on I-74, we encountered two more grades, the second a solid 4 percent. The C15 climbed both without strain.

Before one upgrade I slowed to 55 mph and re-engaged the cruise control for the climb. The C15 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 light traffic. I reduced cruising speed to 55 mph at about 1,225 rpm. The highway dipped and rose steeply through several ravines. Maintaining speed, I braked gently going down and dropped to eighth gear when climbing. I started in second from each traffic stop, evaluating the C15’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.

“We’re getting all positive reports from fleets and OEMs,” Keene says. To keep those tests, as well as this one, true to form, Cat provides the ultra-low-sulfur diesel that the government has mandated for use in all engines beginning next year.

Fuel mileage is expected to be the same, Keene says, though there is not enough customer test data to be more specific. As for pricing, it’s difficult to say how much of Caterpillar’s increased costs will be passed along through truck makers to customers, say Keene and Caterpillar spokesman Jason Phelps.

Even spec’d with flatlander gears and a nine-speed transmission and pulling heavy loads up long inclines, the new engine performs as well as earlier model Cats. There’s no loss of power, weakness or strain.

Spec’d to its maximum 625 horsepower and 2,050 lb.-ft. of torque and matched with the right transmission, rear end and tires, the ’07 C15 should provide enough pulling power to handle the heaviest applications over the long term.

Maintenance questions for 2007 engines focus on the diesel particulate filter, which is about the size and weight of the muffler it replaces.

At road loads, Caterpillar’s new filter oxidizes diesel particulate through a high-heat chemical reaction so that only carbon dioxide and water exit the exhaust. The same reaction reduces engine oil particulate to ash, which gathers in the filter.

“That has to be cleaned out,” says Caterpillar’s Robert Keene. The EPA requires a minimum of 150,000 miles between cleanings. Caterpillar’s target is 300,000 miles.

“It’s about two hours of shop labor, with the DPF either on or off the vehicle,” Keene says.

Moreover, while harder-working engines produce exhaust hot enough to oxidize the particulate matter, exhaust from cooler-running engines must be heated by Cat’s regenerating system, using a small amount of diesel fuel. Keene says a few ounces, “at most maybe every other week,” will do the job. Cat spokesman Jason Phelps says, “Its combustion is totally contained in its cast-iron chamber, and its outer skin temperature never exceeds typical exhaust manifold temperatures.”

The ’07 engines also will suffer less stress than current engines, Caterpillar says, which should help allay maintenance concerns in the long run.


ENGINE: 2007 Caterpillar ACERT C15
TORQUE: 1,850 lb.-ft.
TRANSMISSION: Eaton-Fuller nine-speed
TIRES: 22.5 LP
TRUCK: 2000 Kenworth T2000
GVW: 76,800 pounds
RPM @ MPH AS SPEC’D: 1,270 at 60; 1,325 at 65