Company Touts EGR Results in ‘Fluid Efficiency’ Test
By Jonathan S. Reiskin, Associate News Editor
This story appears in the July 26 print edition of Transport Topics. Click here to subscribe today.
Fleet managers should consider total “fluid efficiency” when comparing trucks using exhaust gas recirculation engines with those using selective catalytic reduction, truck and engine maker Navistar Inc. said last week.
Navistar, whose Class 8 trucks are the only ones in the United States using EGR, said in an online press conference July 19 that fluid efficiency includes the diesel exhaust fluid required by SCR engines along with diesel fuel.
Navistar paid consulting firm Transportation Research Center to compare its ProStar+ tractor powered by a Navistar MaxxForce 13-liter engine with vehicles made by competitors Freightliner Trucks and Kenworth Truck Co. in terms of combined diesel fuel and diesel exhaust fluid usage. Navistar said it beat both rivals.
While Navistar Senior Vice President James Hebe heralded the results, Freightliner’s parent company, Daimler Trucks North America, said the test was invalid.
“Our competitors talk about only one fluid, diesel fuel, and treat DEF as if it didn’t exist,” Hebe said, commenting on claims by SCR proponents that SCR gets better fuel mileage than EGR. The two technologies are alternatives for meeting 2010 federal emissions standards for diesel truck engines.
The tests were run in June and July in northern Indiana. The trucks went around a 444-mile loop three times, a total of 1,332 miles.
The tested Kenworth T660 with a 15-liter Cummins ISX engine used 204 gallons of diesel and DEF — 2.5% more fluid than the 199 gallons of diesel fuel burned by the Navistar truck. EGR engines do not use DEF, a urea-water mixture SCR engines need to remove nitrogen oxides. The study did not break out the amount of fuel versus DEF, but most SCR manufacturers have said the fuel-DEF ratio is usually 50-1.
Kenworth spokesman Jeff Parietti declined to comment.
Against a Freightliner Cascadia with Detroit Diesel Corp.’s DD15 engine, the result was closer: The ProStar burned 194.4 gallons of fuel, and the Freightliner used 196.2 gallons of diesel and DEF, a 0.9% edge for Navistar.
Elmar Boeckenhoff, DTNA engineering and technology senior vice president, objected at length.
“It is neither appropriate nor credible to compare the 12.4-liter MaxxForce ‘mystery’ engine with proven technology available in the market,” Boeckenhoff said. DTNA has shipped more than 3,000 Cascadias with 2010-compliant DD15s to customers this year, he said, while a Navistar spokesman said it will sell its first truck with a MaxxForce 13-liter engine in a matter of weeks.
Boeckenhoff also said the short test length downplays the DD15’s low need for active regeneration cycles for diesel particulate filters.
“DTNA’s BlueTec Detroit Diesel engines regenerate after thousands of miles, not hundreds of miles. The longer the test, the more realistic the results and the closer they are to what a customer would experience in real-world operations,” Boeckenhoff said.
Investment analyst Timothy Denoyer told clients of Wolfe, Trahan & Co. on July 21 that the comparability of the tests was “questionable.”
“Fifteen-liter engines are inherently, modestly, less fuel-efficient due to larger displacement. We question the fairness of the comparison,” Denoyer said.
Hebe told reporters the test used DD15s because they are widely available and because Freightliner has said they are the company’s most fuel-efficient model. In contrast, Navistar has been pushing its 13-liter model as its best and said its 15-liter MaxxForce won’t be in wide production until early next year.
