Photo courtesy of Cummins Westport.

Photo courtesy of Cummins Westport.

Cummins Westport will begin producing the ISB6.7 G, a 6.7-liter dedicated natural gas engine for medium-duty trucks, shuttle buses, and vocational vehicles by the middle of 2016.

The ISB6.7 G is based on the Cummins ISB6.7 diesel engine platform and will operate exclusively on natural gas – either compressed natural gas or liquefied natural gas. The engine is currently in field trials and will have a range of ratings of up to 260 hp and 660 lb.-ft. of torque and automatic transmission capability that can be specified to customer and OEM requirements.

The engine uses Cummins Westport’s proprietary spark-ignited, stoichiometric combustion with cooled exhaust gas recirculation technology. The SEGR technology was first used on the 8.9-liter ISL G engine.

The ISB6.7 G features three-way catalyst aftertreatment that's packaged as a muffler and requires no maintenance, according to Cummins Westport. No diesel particulate filter or selective catalytic reduction aftertreatment will be required.

The engine is expected to be certified at launch to meet the U.S. Environmental Protection Agency and California Air Resources Board emission standards 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.