by Paul Abelson, technical editor
It’s been nine months since the new engine emissions requirements, originally scheduled for Jan. 1, 2004, went into effect for manufacturers party to the agreement with the Environmental Protection Agency.
The engines were introduced with great fanfare and greater uncertainty in October 2002. Then, as now, users wanted to know how the engines would perform over years of ownership. What are the effects of the emissions controls on engine life, on reliability and on fuel economy? Operators want answers to those questions.
Why are 10/02 engines different than previous emissions-controlled engines?
There is one major difference in the engines and another in their development. The engines differ in that emissions requirements are more stringent. To meet them, most manufacturers have relied on some form of exhaust gas recirculation (EGR), along with refinements in their electronic fuel management systems. One, Caterpillar, uses exhaust after-treatment but not EGR.
The development is different because testing time is shorter. In years past, the EPA allowed sufficient time for both process development and field testing to prove reliability and eliminate uncertainty. But in 1998, after the EPA accused six engine makers of providing “defeat devices” that raised levels of nitrogen oxide (NOx) emissions — charges the manufacturers all denied — they agreed to pay penalties and introduce the next generation of engines 15 months sooner.
No one had pockets deep enough to fight the federal government. All but one were able to meet the new standards (Caterpillar’s “Bridge Engines” came close), but none had enough time to do the field testing that not only works the bugs out, but assures customers of the engines’ reliability.
How do the engines stack up so far? At the 2003 annual meeting of the Technology and Maintenance Council (TMC), a panel of fleet maintenance executives described their experiences with late developmental and early production engines.
Concerns involved engine service intervals and oil analysis, driver acceptance and fuel economy. It is too early to reach conclusions about long-term reliability and durability.
Joe Stianche, fleet manager of Sanderson Farms, ran his tests with 12 post-10/02 C-12 engines and an equal number of pre-10/02 control engines. The C-12 is a “bridge engine,” bridging the gap until the ACERT C-13 will be certified in October. The test and control engines were otherwise identical, matched by service assignments. Various operations within the company run from 125,000 miles to 170,000 miles per year.
Because of the larger diameter muffler needed for exhaust after-treatment, Stianche said, “The converters take a little more room and may cause trailer-cab clearance issues.” Oil drain intervals remain unchanged, but Stianche plans to analyze oil more frequently. Driver attitude ranged from “no difference” to “improved responsiveness.”
Fuel economy is down 0.48 mpg (7.5 percent) in over-the-road long-haul operations and 0.84 mpg (14.5 percent) in the feed-haul fleet. These may be tempered, Stianche told the group, because fuel economy is usually 0.40 mpg to 0.50 mpg worse in winter months. Factoring in climate, the feed haul tractors may be only 4 percent to 6 percent down, and long-haul mileage may be only 2 percent worse.
Dennis Soch is fleet operations manager for Keebler. His Volvo engines use cooled EGR. Soch uses bypass filters on all his engines, including the post-10/02 models, and he drains oil on both pre- and post-10/02 engines at 25,000 miles. No problems with the new engines have been reported.
Fuel economy for his two twin-screw test tractors was off by 1.5 percent on one and 0.7 percent on the other. The single drive axle tractors averaged only 0.5 percent poorer fuel mileage.
“Driver acceptance has been good,” Soch said, but “the jury is still out.”
Sam Kennedy reported on his experiences with Mack engines. He is chief maintenance officer of D.M. Bowman Inc. Mack also uses cooled EGR for its on-highway applications. As with all cooled EGR engines, Mack has engine-mounted heat exchangers to bring exhaust gas temperatures down. While Kennedy reported no engine problems, the higher under-hood temperatures boiled the windshield washer fluid in four test trucks. Also, four ECU modules and one air compressor had to be replaced.
Drivers liked the new 427 hp Macks, remarking that the engines were quieter and smoother, although one driver said the turbo was a little louder. Fuel economy averaged 4.7 percent less than with the control engines.
Jeff Phlipot, director of maintenance for Kirk Nationalease, placed Cummins test-and-control engines in two fleets that operate with similar ratings and similar applications. At the panel presentation, Philpot mentioned that he was still trying to determine the best parameter settings. By reprogramming one truck’s ECU settings, fuel economy was increased from 5.4 to 6.2 mpg.
Phlipot reported minimal low-mileage engine problems. Based on three failures, he projects a 2 percent injector failure rate in 425,000 miles. Drivers like the quicker throttle response and good pulling power of the new engines.
Dwayne Haug, vice president of maintenance for Werner Enterprises, operates a large fleet of Detroit Diesel engines. He ran TMC/SAE-controlled fuel economy tests in which the post-10/02 engines averaged from 5.5 percent to 6.0 percent poorer mileage. Similar tests run by Detroit Diesel showed 4.8 percent to 5.6 percent reduction in mpg.
Haug ran both pre-production test engines and regular production models, so he has more experience than most other operators, but still not enough to assess longevity and durability.
Detroit claims that because of its bus business, the company has more experience than any other manufacturer with cooled EGR. Urban buses have had to meet more stringent emissions regulations for the past several years.
Haug reports that drivers like the way the new engines spool-up more quickly, but many other questions remain.
Since the TMC panel was held in March, Caterpillar has started rolling out its certified ACERT engines. The company expects all models to be certified and available by the end of the year. The C-13 will replace the C-12 heavy-duty engines. The C-15 will have slightly larger displacement.
Since all makes of engines but one use cooled EGR for on-highway use, underhood temperatures have increased an average of 5 degrees F. Truck builders are paying close attention to underhood components, especially those near the EGR cooler. Early engines had the fan running (and lowering fuel economy) as much as three times more than with pre-10/02 engines, but software changes have brought fan-on time down to about the same as before.
Changes to truck architecture to accommodate higher temperature include larger radiators and higher capacity water pumps, among other modifications. Coupled with the EGR equipment on the engines or Caterpillar’s exhaust aftertreatment, the changes have raised truck prices between $3,000 and $6,000.
It may take until 2004, the originally scheduled test period, before operators gain enough confidence with the new engines to see sales volume increase significantly. In my opinion, it won’t be long before we’ll all be buying the post-10/02 engines, if for no other reason than fear of the far more restrictive 2007 emissions standards. LL
Paul Abelson can be reached at email@example.com.