Ultra-Low Emission Natural Gas 12-Liter Engine for On-Road Heavy-Duty Vehicles

Heavy-duty on-road diesel vehicles are currently among the top ten sources of NOx (oxides of nitrogen) emissions in the South Coast Air Basin. The development of ultra-low emission natural gas engines would significantly reduce emissions from this category of vehicles and assist the region in meeting federal ambient air quality standards in the coming years.
The project team designed, developed, demonstrated, and achieved California Air Resources Board and United States Environmental Protection Agency certification of an ultra-low emission 11.9-liter natural gas engine, named the “ISX12N”. The ISX12N represents an upgrade to the current ISX12 G production engine, with an improved three-way catalyst, a closed crankcase ventilation system, and optimized engine controls that improve upon the base design and meet state engine certification goals. The project team also developed heavy-duty on-board diagnostics to meet California Air Resources Board requirements.
The project proved the technical and commercial viability of the ISX12N engine, and the engine was able to meet the certification requirements for the California Air Resources Board’s most stringent Optional Low NOx standard as well as the United States Environmental Protection Agency’s current criteria pollutant and greenhouse gas emissions standards.
The project successfully demonstrated the ISX12N engine in on-road heavy-duty vehicle applications including regional haul truck and refuse truck applications. Fifteen field test units supplemented the rigorous engine testing by accumulating mileage in real-world operation and addressing unforeseen issues prior to the engine entering commercial production, thereby improving product reliability. The engine moved to commercial production in February 2018.