Despite the decision of all other North American engine suppliers to adopt selective catalytic reduction, Navistar Truck and Engine Group says it still plans to offer “in-cylinder” diesel engine emissions solutions for the North American truck market in 2010. Navistar’s 2007-compliant big bore MaxxForce engines are now in limited production at its Huntsville, Ala., plant.
In a meeting last week with CCJ and other Randall-Reilly Publishing trucking editors, Timothy Shick, director of marketing for Navistar’s Engine Group, said the company will use its banked Environmental Protection Agency emissions credits to buy the time necessary to calibrate its engines to achieve the agency’s demands for oxides of nitrogen (NOx) reductions. Navistar received credits for earlier-than-required compliance and lower-than-required emissions performance dating back to the first exhaust gas recirculation (EGR) engines marketed by the company in 2004.
“We’ve stockpiled these credits, and it’s a ‘use them or lose them’ proposition,” Shick says. “All Navistar MaxxForce engines will be emissions-compliant for 2010, just as they are today. If they weren’t, we couldn’t sell them. Some Navistar engines are currently emitting emissions below required 2007 levels, and the EPA encourages and rewards this performance.”
In effect, Shick says Navistar’s early good performance in the emissions arena has bought the Warrenville, Ill.-based company time to tinker with and optimize the emissions performance of its in-cylinder solution without relying on urea-based selective catalytic reduction (SCR) to neutralize NOx in the exhaust stream, as other North American engine suppliers will be doing.
In Navistar’s solution, a high-pressure common-rail fuel injection system delivers diesel in a finer mist and with improved sequencing to allow for a more efficient fuel burn, Shick says. The MaxxForce’s high-strength compact graphite iron engine block is designed to handle the higher pressures. Other elements of the package include a proprietary combustion bowl design and advanced air management using exhaust gas recirculation. Some of the attributes of the MaxxForce include lower weight relative to competitors and the ability to achieve full torque at a lower rpm, allowing drivers to maintain top gear longer.
“Ultimately, Navistar doesn’t believe SCR technology is mandatory for meeting 2010 emissions regulations,” Shick says. “Our engineers are currently working hard on finding in-cylinder NOx and particulate emissions solutions that will give our customers productive, fuel-efficient and clean diesel engines without the added weight or complexity SCR systems add to trucks.”