COLUMBUS, Ind. — Cummins has expanded its on-highway natural gas engine lineup with the Cummins Westport ISX12 G and an amended joint-venture agreement with Westport Innovations.

The ISX12 G is built on the Cummins ISX12 and uses the same base engine and key components. It features Cummins Westport’s spark-ignited combustion technology with stoichiometric-cooled exhaust gas recirculation (SEGR), first introduced on the 8.9-liter ISL G.

The engine will run on either compressed or liquefied natural gas and is expected to be immediately certified to meet the US Environmental Protection Agency (EPA) and California Air Resources Board (ARB) emissions standards of 0.20 grams per brake horsepower-hour Oxides of Nitrogen (NOx) and 0.01 grams per brake horsepower-hour Particulate Matter (PM). The engine is expected to meet Euro VI and pending US greenhouse gas and fuel efficiency regulations.

The ISX12 G is maintenance-free and will feature three-way catalyst after-treatment packaged as a muffler, according to officials. Ratings up to 400 hp (298 kW) and 1450 lb-ft (1966 N.m) of torque and an optional engine brake.

“The ISX12 G will be well-positioned to lead in heavy-duty vocational and regional-haul markets,” said Ed Pence, Cummins vice-president and general manager of heavy-duty engine business.

The ISX12 G is entering the final stages of field-testing and will be manufactured at Cummins Jamestown Engine Plant in Jamestown, N.Y. in 2013.

Partial funding in support of the ISX12 G engine development has been received from the US Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) and the California Energy Commission in conjunction with the Gas Technology Institute.

Additional terms and conditions of the joint-venture agreement were not disclosed.