Curious. Dealers eyed new turbocharger (top) and engine (bottom). (Photo by Tudor Hampton for ENR)

Clean diesel engines are making considerable gains in fuel economy, but maintenance issues are still up in the air, equipment dealers say.

Mack Trucks’ latest round of low-emission engines, available next year, are at least 2 to 3% more fuel-efficient than previous power trains. For construction work, where older, heavy-duty engines have a thirst for fuel, users may even see double-digit percent gains, the manufacturer claims.


The new “MackPower” series is the Allentown, Pa.-based vendor’s most-extensive engine rollout in 40 years. It is designed to help Mack meet federal emission cuts required in January 2007. Six new engines will lead the charge, all with 11-liter displacement. Horsepower ranges from 325 to 405 and torque from 1,260 to 1,560 ft-lb. The “MP7” will power the company’s updated Granite series of work trucks and a new, sleek-looking highway truck, called the Pinnacle.

Mack plans to launch a 13-liter “MP8” engine line in 2007, with 16-liter “MP10” units to follow. All will use cooled-exhaust-gas recirculation, variable-geometry turbocharging and electronically controlled injectors.

The introduction marks a significant change in Mack’s power train. It uses engineering from its Gothenburg, Sweden-based parent company, Volvo Group, while adding its own traditional robustness. Volvo unveiled its own line of 2007 engines on Oct. 17, noting that it spent $150 million to upgrade its North American engine plant in Hagerstown, Md. Both firms have dumped cash into research and development for regulations in the U.S., Europe and Japan. “A lot of R&D must be done to stay competitive,” says Jorma Halonen, Volvo’s deputy CEO and Mack’s chairman.

(Photo courtesy of Mack Trucks Inc.)

Starting in January 2007, the engines will change yet again, with the addition of diesel particulate filters, which trap soot in the tailpipe. By 2010, when another emission cut takes effect, engine manufacturers plan to use more tailpipe devices to reduce emissions of nitrogen oxides. But they are not ready to discuss specifics. One problem in the U.S. is a limited supply of NOx-neutralizing chemicals, such as injectable urea.

Made by Cummins’ Fleetguard unit, Mack’s soon-to-come particulate filters will eliminate mufflers. But they are three times as heavy as traditional mufflers and are bulkier, which may limit space behind the cab. Particulate filters also require periodic cleaning with expensive equipment. Dealers may opt to send dirty particulate canisters to a remanufacturer, rather than investing in the equipment themselves, said some at a sales meeting Oct. 23 in Las Vegas.

Owners say they need years to catch up with the changes. Field testing helps, but manufacturers “need to get better at building a track record before [the engines] go into normal production,” said Pete Witt, sales manager at Virginia Truck Center Inc., Roanoke, Va.

Mack is giving fleet owners extra time to adjust. Next year, they can choose between the premium-priced MP series and older, less-efficient engines. When the 2007 emissions regulation goes into effect, the old units will be discontinued.

That also gives Mack and Volvo time to retool. “We feel more comfortable with phase-ins and phase-outs, than Friday-to-Monday,” said Mack President and CEO Paul Vikner. Gains in fuel economy in next-year’s MP engines may help soften the bottleneck of an industry phenomenon known as a “pre-buy,” when construction fleet owners stock up on older-style engines in the months leading up to an emission mandate.

Dealers still expect a sales rush. They are forecasting steady sales into late 2006, with a major slowdown in 2007.