August 13, 2008 Vol. 4, No. 17

WOW! BIG NEWS out of Indiana hit the street today as Cummins announced that it’s going to use selective catalytic reduction (SCR) technology in its 2010 heavy-duty ‘X’ engines after all. That reverses its announcement of not quite a year ago, when the Indiana engine-maker said it could meet the next EPA emissions standard with an enhanced version of cooled exhaust gas recirculation (EGR) for its 15-liter engines, needing no NOx aftertreatment and thus no SCR.

“Cummins will combine recent advancements in catalyst technology with its unique engine systems,” Cummins said. “This will provide customers with significant fuel economy improvements, in addition to meeting the near-zero emissions levels required by the Environmental Protection Agency’s (EPA) 2010 regulations.”

The SCR aftertreatment system will be built in-house by Cummins Emission Solutions.

“As previously announced, Cummins heavy-duty ISX engine family will incorporate the XPI fuel system, proven cooled exhaust gas recirculation, the Cummins VGT turbocharger, Cummins particulate filter and advanced electronic controls… We have the capability to make the engine systems and aftertreatment technologies work together seamlessly,” said Steve Charlton, vice president, heavy-duty engineering.

Presumably, the EGR system in use here will be less aggressive than the one originally planned.

“This move demonstrates Cummins ability to adapt to a changing environment by leveraging technology advancements from our mid-range engine development and Cummins Emission Solutions,” said Ed Pence, vice president and general
manager, Heavy-Duty Engine Business. “Our 2010 engine development is progressing on plan, and customers can depend on Cummins to deliver these new products on time.”

Details on the Cummins decision to switch to SCR were not available as I was writing this, but an informed source close to the action says it has everything to do with the proven ability of SCR engines to increase fuel economy compared to EGR motors. With fuel prices skyrocketing, the logic here seems solid, as the use of EGR alone would, at best, maintain the status quo regarding fuel economy. SCR, and less aggressive in-cylinder tools, will likely accomplish a fuel economy improvement of at least 2 or 3%.