Gray Expectations

The rush to design October 2002 engines created concerns that the strategies used to comply with emissions requirements were likely to reduce efficiency and increase engine stresses. Sales of pre-October engines spiked in mid-2002. Orders of the new engines lagged for months after introduction.

Results two years later, though mixed, suggest the new engines do the job. Fuel economy and reliability have been generally good, especially as manufacturers tweaked their product lines and customers adjusted to new maintenance and operating requirements.

The new engines perform better than their predecessors. Drivers operating engines with variable geometry turbos universally praise the instant throttle response. The variable nozzle is used to spin the turbo up more quickly. And, says Bob Maddox, president of Nick and Dee’s Trucking of Hereford, Texas, the torque on his Cummins 475-hp ISX “hangs in there better between about 1,200 to 1,400.”

Though it doesn’t have a variable geometry turbo, Volvo’s EGR engine has a much wider power curve and “pulls like a freight train,” says Jim Fancher, Volvo Trucks of North America marketing manager. Caterpillar’s ACERT, too, offers substantial increases in bottom end performance.

Drivers also say that EGR makes a considerable difference in cold weather warm-up. Only a brief idling period is required to heat the cab.

Partly because of truck design modifications, the engines can hold their own in converting fuel to delivered loads. Customers rarely report more than a 4 percent to 5 percent degradation in fuel economy, and some have experienced better fuel economy. Improvements in performance that allow faster gearing help, too.

CATERPILLAR. “We targeted our ACERT engines to give the same fuel efficiency as pre-ACERT engines,” says Greg Gauger, director of on-highway engine products. Caterpillar’s new engines rely upon the proprietary ACERT technology to reduce emissions; competitors use exhaust gas recirculation. He says at least two carriers have reported improved fuel economy with ACERT engines – Dana Suttles Transportation of Demopolis, Ala., which has Freightliners pulling tankers, and South Georgia Brick Co., which saw fuel economy jump from under 6 mpg to 6.84 mpg with its C-13s.

However, “You need to spec and drive them correctly to get the best possible fuel economy,” Gauger adds. “When we get complaints, we have found the customers are not following the driving recommendations.”

Bob Keene, Caterpillar’s customer value manager, explained why it’s okay to gear ACERT engines differently and achieve better fuel economy. “ACERT engines have a larger displacement and series turbos, so there’s more airflow,” he says. The C15, for example, has gone from 14.6 liters to 15.2 liters. “You can run them at lower rpm. Drop one axle ratio from what you were running before, as long as you don’t get into trouble with gradeability.” You should also increase your torque rating to 1,750 pounds-feet or more, Keene says.

“A C15 should be running at 1,400 to 1,450 rpm at a little more than 70 mph. You should be turning 1,325 rpm at 65 mph. It’s an expansion of the gear fast, run slow concept, and the engines will still perform well at that rpm,” says Keene. This is partly because peak torque now exists down to 1,100 rpm.

Canfield, Ohio, owner-operator Earl Evans understands this change in the Cat engines. He just ordered a Kenworth with a C15, specifying 3.08 rears with low-profile tires.

Jim Booth, running eight trucks leased to Midwest Specialized Transportation, gets fairly good fuel economy – 6.57 mpg over 80,000 miles, most of the time below 60 mph. His Kenworth has a C15 ACERT engine rated at 550 hp. The truck is geared as Caterpillar suggests, with 3.25 rears, meaning the engine turns only 1,325 rpm at 65 mph.

CUMMINS. A fuel economy loss of 3 percent to 5 percent was predicted when Cummins released its EGR-equipped ISX series. “That expectation for the ISX had proved remarkably accurate,” says Kevan Browne of Cummins.

Customers have reported a wide range of results – in excess of 5 percent loss, and in some cases improved fuel economy, says Browne. For example, John Hall of Big Lake Transport, Charleston, Mo., said his ’02 ISX engines were “within about 0.4 mpg” of his pre-’02 fleet at 80,000 miles, according to Cummins literature.

Tom Gilkey of Safeway Division, Portland, Ore., reported to Cummins that his fuel economy was comparable with the fleet’s pre-’02 engines, which was what he had expected. One large truckload carrier reported 4 percent degradation in its fuel economy, says Browne, who declined to name the customer.

Maddox says not idling enabled him to gain “one half to one mile per gallon” over his previous 600-hp Cummins Signature. When Maddox got his Kenworth W900 with a 475-hp ISX, he equipped it with a battery-powered air conditioning system by Bergstrom that eliminates overnight idling. Instead of the normal low 6-mpg range, he got 6.8 mpg in a recent run from Indianapolis with his truck, grossing more than 79,000 pounds.

DETROIT DIESEL. Customers have experienced a fuel economy loss of 3 percent to 5 percent, says Chuck Blake, manager of customer fuel consumption analysis for Detroit Diesel. “I’ve seen a few fleets with a little less, one or two with more, but the number is consistently in that ballpark,” he says. Blake says that both the Series 60 and the Mercedes-Benz engines should be geared for a cruise around 1,500 rpm for anything 80,000 pounds and less. For overweight loads, cruising around 1,625 rpm is recommended. The optimal downshift is at 1,300 rpm or less; try to pull a hill without shifting till you get down to 1,200 rpm, Blake suggests.

MACK. Dave McKenna, powertrain marketing manager at Mack, says that the company’s ASET technology has proven very competitive, especially in fuel economy – “anywhere from no decline to a 3 percent degradation,” he says. Like most of its EGR competitors, the ASET highway engine uses a variable geometry turbo and EGR jacket water cooler.

VOLVO. Customers were told to expect an average of zero to 2 percent fuel economy loss, says Fancher. “Most users indicate performance within that range,” he says. “One carrier with more than 400 units saw a change of half of 1 percent.”

The pulse system used to recirculate the exhaust helps minimize the effect of back pressure, which is used with variable geometry turbos to recirculate exhaust.

Fancher says improvements in the grill and under-hood areas, with a sealed engine compartment, have improved airflow and minimized the fan on-time. Mounting the fan shroud on the engine also helps the fan operate more efficiently.

Ed Saxman, director of powertrain systems, says that while the rating of the most powerful engine, the 465, is the same, its sweet spot has edged down from 1,400-1,600 rpm to1,400-1,550 rpm, and its power curve is much flatter. “Owners who ran 3.73 rear axles can now run 3.58 axles because peak horsepower is available over a wider range,” he says.

With EGR, there is not only considerably more heat passing through the engine, but there may be an increase in acids and soot. Acid gets recycled with the old exhaust. Soot may increase because, with recycled exhaust in the combustion chamber, the burning fuel may reach the cylinder liner. For this reason, the new CI-4 oil designation was developed to help protect engines and optimize maintenance schedules.

Some engine makers, however, have created other designations to accommodate their particular technology. The oil container’s label will include not only CI-4 or CH-4, but every other designation the oil passes.

CATERPILLAR. Cat’s Gauger reports that the stresses on oil with ACERT are so low that CI-4 isn’t necessary; the former standard, CH-4, will do. However, any oil should contain Cat’s ECF-1 designation, which indicates a simple limit on the amount of sulfated ash in the oil to counteract acids.

Gauger says the standard change interval for engines getting 5.5 mpg to 6.5 mpg remains 30,000 miles. Pan capacity on the C15 remains the same, but on the C13 it was increased by one gallon to maintain the change interval.

Coolant maintenance remains the same. Caterpillar recommends extended life coolant.

CUMMINS. The standard change interval was shortened from 40,000 to 25,000 with the 2002 engines. The recommendation is CI-4 oil with the CES 20078 designation. CI-4 Plus is not required. The interval can be increased to 35,000 miles if the customer uses Cummins Valvoline Premium Blue. Maddox says he changes at 25,000, but will begin using Premium Blue to take advantage of the extended interval.

Coolant service intervals remain the same. The long-life coolants are now compatible with Cummins engines.

DETROIT DIESEL. Blake says the “no-brainer” oil change interval remains at 15,000 miles, but many fleets go to 20,000 or 25,000. “When running that far, it’s smart to use oil analysis,” he says, as well as quality CI-4 Plus oil. Analysis can detect a tiny leak in an EGR cooler by indicating an increase in potassium. The problem can be corrected by replacing the cooler before there has been any engine damage.

Detroit had a few problems with its earlier plate-and-fin-type EGR cooler. It was replaced with a shell-and-tube design that Blake says has proven to be “bulletproof.”

MACK. The size of the oil pan was increased with the 2002 engines to optimize drain intervals. The engines require CI-4 oil with the EON designation. Change intervals were shortened from 40,000 miles to 25,000 for ASET engines with cooled EGR. Intervals are the same for the vocational engines with internal EGR, except on a special front-loader chassis.

Coolant service intervals are the same.

VOLVO. Oil pan capacity remains the same. Oil change intervals, running the required CI-4, also are the same (15,000 miles in normal service). However, Volvo field reps have worked with customers to approve extended intervals.

Coolant service intervals and the engine operating temperature are unchanged, but “it’s even more important to follow them to the letter,” says Fancher.

Reports about engine problems seem to focus on turbochargers and, occasionally, EGR coolers, but engine makers report that running changes during production have improved reliability.

Mack greatly improved its turbocharger compressor early in the introduction of its 2002 engines so it would withstand the higher rpm. Detroit Diesel recently redesigned its EGR cooler. Most coolers are now made entirely of stainless steel to counter corrosion.

To refine its ACERT technology, Gauger says, Caterpillar adopted a very intensive quality control program that incorporates the well-known 6 Sigma manufacturing standards. As a result, “We have essentially the same reliability as our previous products,” he says.

At Cummins, “The reliability of our ISM and ISX engines has exceeded expectations,” Browne says. John Hall of Big Lake Transport of Charleston, Mo., reports “almost nil” maintenance requirements for his ISX engines. The only trouble Maddox had was fault codes popping up when there wasn’t a problem, which the dealer fixed in 10 minutes, he says.

Volvo’s Fancher says the VED12 engine has seen relatively few changes since its introduction in 1993, giving time to make it reliable. The VED12 with EGR does use a “slightly larger oil cooler, and there is more airflow through the radiator” to carry away the extra heat. Under-hood temperatures have increased very little because of airflow improvements, which should help reliability.

Mack’s McKenna says, “We’ve seen about what we expected in terms of these kinds of issues, and we’ve worked closely and diligently with our dealers and customers to address them.”

That’s what happened with D.M. Bowman Inc., a large fleet in Hagerstown, Md. The company’s maintenance director, Sam Kennedy, says one of the carrier’s Macks with ASET highway engines using cooled EGR had a turbo failure. By that point, Mack had already addressed the problem in production by replacing the aluminum compressor wheel with a titanium design to withstand the higher operating rpm. Bowman’s problem was rectified by installing one of the new turbos.

For longevity and the highest operating efficiencies, McKenna provides good advice for owners of any EGR engine: “Heat rejection is up. Even though cooling system efficiency is greater, the two most important words in the post-’02 lexicon are ‘preventive maintenance.'”

Buying a new truck? Here are some tips on getting the most efficiency out of a drivetrain with EGR or ACERT technology:

  • Get plenty of help from the truck, engine and drivetrain manufacturers to optimize the powertrain. Gear differently by dropping an axle ratio unless you are in a hard-pulling application. Specify more torque than in the past so you can run at a low enough rpm.
  • Adopt idle-reduction accessories and run at a lower speed or buy a more aerodynamic truck. You can get at least the same fuel economy you get now, if not better.
  • Reduce the cost of more frequent oil changes by using the best oil and following the engine manufacturer’s recommended change intervals, if you’ve been changing at a very conservative mileage. You also can use oil analysis and explore extended intervals.
  • When driving, leave the gearshift alone unless you run out of power well before cresting a hill.

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