Medium diesels ready for low-emissions

Nov. 1, 2003
Gary Mandell, vehicle specifications specialist and purchasing manager for Decarolis Truck Rental, Rochester, NY, views the impending introduction of low-emission diesel engines for Class 3-7 trucks this way: it's a mix of good and bad news for fleet operators. The substantial cost differential between the new engines and previous models is the main concern, he says. That will increase the base cost

Gary Mandell, vehicle specifications specialist and purchasing manager for Decarolis Truck Rental, Rochester, NY, views the impending introduction of low-emission diesel engines for Class 3-7 trucks this way: it's a mix of good and bad news for fleet operators.

“The substantial cost differential between the new engines and previous models is the main concern,” he says. “That will increase the base cost of a truck, which is worrisome because things are so tight for fleets in today's economy.” The reduced fuel economy predicted for most of these engines doesn't help either, Mandell notes. He adds that fleets could stop spec'ing options, such as air conditioning, to compensate for the higher cost of low emission engines.

However, Mandell feels strongly that the good news could balance out many of the negatives associated with 2004 low-emission diesel truck engines. “There are definitely two positive parts to this story. These engines will have more power and will be more responsive,” he explains. “Having more power could actually help with fuel economy in the long run, because more power means drivers have to use the throttle less often to get up to speed.”


Most engine manufacturers are using some form of pollution control technology to meet the 2004 standards. International Truck & Engine Corp., Hino Diesel Trucks, and General Motors Isuzu Commercial Truck, for example, are all using exhaust gas recirculation (EGR) systems to reduce diesel engine emissions. While Mitsubishi Fuso's parent company has developed an EGR engine for the Japanese market, it has not decided whether to import that technology for use on the trucks it sells in the U.S. Caterpillar is using a different technology altogether, called advanced combustion emissions reduction technology (ACERT), to achieve the stricter emissions levels.

Cummins Engine Co., on the other hand, has decided not to use its EGR systems on its '04 medium-duty engine line. To achieve EPA certification for its '04 ISC and ISL diesels, Cummins used credits awarded by the agency when it reduced emissions output on other engine lines even further than was required by EPA.

Carol Lavengood, director of market communications for Cummins, points out, however, that Cummins considers EGR a foundation technology for all its engines in meeting even stricter '07 requirements. This means that at some point in the future EGR will be integrated into the company's medium-duty engine line.

Also, since most '04 engines are larger than current models due to new pollution-control technology, some OEMs have had to reconfigure their chassis to make room for the new engines. For example, Sterling's HX chassis for A-Line and L-Line vehicles was designed to accommodate the needs of EGR-equipped engines, as well those using ACERT (Caterpillar's technology).

“With EGR, there's more heat being produced by the engine, so we had to increase the capacity of the cooling systems,” says Landon Grogan, project manager for HX. “With ACERT, the cooling needs don't change, but you need a heavier muffler to handle the aftertreatment system. That means some fleets will have to move to a dual exhaust stack set-up instead of the single exhaust they used before.”

Though Sterling made a host of other upgrades to its HX chassis (see Nuts & Bolts, this issue) it was the change to '04 engines that served as the driving force behind the redesign of it chassis in the first place. “We undertook this project because of the various upgrades required by '04 engines,” Grogan notes.

Fleets will find that the potential advantages and disadvantages of '04 engines will depend largely on the brand of engine they buy and the truck application it's intended for.

The most obvious negative is the higher price tag, which EPA says could range anywhere from several hundred dollars to over $1,000, depending on factors like engine size and power rating.

Most of the manufacturers FLEET OWNER spoke to would not comment on engine price increases. But it's an issue that is giving some fleets considerable pause when it comes to future truck purchases. “The price increase concerns us most,” says George Survant, director of fleet services for electric utility Florida Power & Light Co. “As a result, we don't expect to buy too many right now.”

However, most '04 engines feature improvements that may outweigh the price increase in the long run — if the results engine makers have seen so far can be achieved in real-world operations.

According to Patrick Charbonneau, vp and chief technology officer for International's engine group, the higher performing engines do more than meet stricter emissions requirements; they also feature extended capabilities.

“We're offering greater horsepower range, improved fuel economy over the current product, an improved turbocharger for more responsive acceleration, and engine brakes integrated into the vehicle's electronic control system for improved stopping power,” he says.


“Our '04 engines were designed with EGR technology in mind. This is not an engine we had to add EGR to; it's a cornerstone of the design,” adds Tim Shick, director of marketing for International's engine group.

New technology on the '04 versions of International's VT 365 V-8, DT 466, and DT 530 engines will not only put them in compliance with new low-emission requirements, but should also boost many of their operating characteristics, he says.

First, instead of having two valves per cylinder, International's mid-range diesels will have four. Second, the engines feature a common rail high-pressure fuel system that does not have the external lines that can lead to pressure leaks, which hurt performance.

Third, a new digital G-2 spool valve replaces the analog solenoid valve previously used, increasing control of fuel consumption. Finally, an electronic variable response turbocharger (EVRT) helps boost both low- and high-end engine performance while also minimizing fuel consumption, says Shick.

International says its '04 VT 365 gets 5% to 10% better fuel economy, while the DT line should see a 5% improvement.

Derek Kaufman, spokesman for Hino, says the company's new conventional medium-duty truck will feature engines equipped with variable geometry turbochargers, a common rail fuel injection system, and water-cooled EGR. He says fuel economy losses will be minimal and that customers should experience equal performance or better because of the new turbocharger and fuel injection system.

“The market is understandably a little on edge because both raw engine prices and operating costs will increase,” Kaufman explains. “But there are also a lot of benefits to the new engine systems.”

Dan Cutler, director of low-cab-forward product development at GM Isuzu, adds that the long-range benefits of '04 engines may outweigh price concerns. “All most fleets have heard is that they'll lose fuel economy and performance with these engines,” he says. “In actuality, we've improved engine performance by increasing horsepower and toque; that's why fuel economy may suffer a little.”

Cutler says GM Isuzu's new 6-cyl. '04 engine features a variable geometry turbocharger, hi-pressure common rail fuel injection system, and water-cooled EGR. The engine also has 16 valves, compared to 8 on previous models, thus boosting power and performance. “In our case, we're getting a lot more than just emission reduction with the '04 engines,” he says. “The up-charge shouldn't be a hindrance since you're getting more power and thus more capability from the engine, without sacrificing durability or reliability.”


Fleets buying trucks with '04 engines that don't use EGR to meet the new emission standards will see quite a few changes. Caterpillar, for example, is using ACERT technology to reduce emissions for its C-7 and C-9 engines, which will replace the 3126 models used by most medium-duty Caterpillar customers.

ACERT features an air management system that recovers exhaust energy in order to lower in-cylinder combustion temperatures, thus reducing emission levels, according to Caterpillar. In addition, ACERT uses an aftertreatment in the exhaust system to reduce particulate matter.

Although Cummins is not using EGR technology on its medium-duty diesels for now, the company has made performance-enhancing improvements to these engines.

According to David O'Brien, the company's market product leader, the upgrades and changes for the ISC and ISL include a new fuel system and increased engine block and cylinder head strength, as well as a variable geometry turbocharger for the ISL.

The ISC and ISL engines use a High Pressure Common Rail (HPCR) fuel system, which provides multi-injection capability, reduced noise and emissions, and improved cold starting. The design maintains high injection pressures regardless of engine rpm, he notes.

Mitsubishi Fuso Truck & Bus Corp. has launched a Super Great series model vehicle equipped with an EGR engine in its home market, Japan, but hasn't decided whether to apply that technology to the cabover trucks its sells in the U.S., says spokesman Joe Devlin.

He points outs, however, that in terms of engine characteristics, when the 2002 big bore engines came out “it ended up being a non-event for the big fleets; they really didn't see too much change in engine characteristics. We expect something similar on the medium-duty side.”

Decarolis' Mandell thinks that whatever technology or method is used to meet the '04 rules, much of the medium-duty industry should handle the change just fine.

“Some people are understandably concerned about the upfront cost increases,” he says, “but coupled with the reported performance improvements we'll be getting, in the end I think we'll come out ahead.

“We're getting more power and better performance with the same durability and reliability as before,” Mandell adds. “That should help us better match the fuel efficiency curve of the vehicles we lease and rent, so over the long term that benefit should exceed the cost of the new engines.”

About the Author

Sean Kilcarr | Editor in Chief

Sean previously reported and commented on trends affecting the many different strata of the trucking industry. Also be sure to visit Sean's blog Trucks at Work where he offers analysis on a variety of different topics inside the trucking industry.

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