Kenworth Truck Co. is broadening the availability of the 8.9-liter Cummins Westport ISL G “near zero NOx” natural gas engine among its truck models.

Rated at 320 hp and 1,000 lb-ft of torque, the exhaust emissions of the Cummins Westport ISL G NZ are 90% lower than the current Environmental Protection Agency (EPA) and California Air Resources Board (CARB) NOx limit of 0.2 g/bhp-hr (grams per brake horsepower hour) and also meet the 2017 EPA greenhouse gas (GHG) emission requirements, according to the OEM.

Kenworth is making this engine available on its T680 on-highway tractor plus and T880 and T880S vocational models, noted Kurt Swihart, the OEM's marketing director, in a statement.

“The Kenworth T680 and T880 specified with the ISL G NZ engine are ideal for regional haul, vocational and refuse fleets focused on decreasing their environmental impact and reducing operating costs,” he said.

Cummins Westport said is ISL G NZ uses an advanced engine calibration, a unique three-way catalyst after-treatment system, and a closed crankcase ventilation system to help achieve this reduction in oxides of nitrogen (NOx) emissions.

The company added that its engine operates on 100% natural gas, which can be carried on the vehicle in either compressed natural gas (CNG) or liquefied natural gas (LNG) form and is also compatible with renewable natural gas (RNG).