At the 2015 Alternative Clean Transportation (ACT) Expo in Dallas, Cummins Westport Inc. has debuted the ISB6.7 G, a 6.7-liter dedicated natural gas engine targeted for school bus, shuttle bus, medium-duty truck and vocational applications. The new ISB6.7 G is currently in field trials, with full production expected to commence in mid-2016.
The factory-built ISB6.7 G natural gas engine is based on the medium-duty Cummins ISB6.7 diesel engine platform. The ISB6.7 G will operate exclusively on natural gas (compressed or liquefied) utilizing Cummins Westport's proprietary spark-ignited, stoichiometric combustion with cooled exhaust gas recirculation (SEGR) technology, first introduced with the 8.9-liter ISL G.
According to Cummins Westport, the ISB6.7 G features three-way catalyst aftertreatment, which is packaged as a muffler and is maintenance-free. No diesel particulate filter or selective catalytic reduction aftertreatment will be required, the company adds.
Preliminary specifications include a range of ratings to 260 hp and 660 lb-ft torque and automatic transmission capability to meet customer and original equipment manufacturer requirements.
‘The ISB6.7 G will offer customers low-emissions with diesel-like performance, reliability, and durability and a choice of either compressed natural gas or liquefied natural gas as a fuel,” comments Rob Neitzke, president of Cummins Westport.
The ISB6.7 G is expected to be certified at launch to meet the U.S. Environmental Protection Agency and California Air Resources Board emission standards of 0.20 g/bhp-hr NOx and 0.01 g/bhp-hr PM and 2016 U.S. greenhouse gas and fuel economy regulations. The ISB6.7 G will be manufactured in Cummins' medium-duty engine plant in Rocky Mount, N.C.
Partial funding in support of the new engine's development has been received from the California Energy Commission through its Public Interest Energy Research Program in conjunction with the Gas Technology Institute.