Cummins Westport L9N
The Cummins Westport L9N is an 8.9-litre, six-cylinder inline natural gas engine for shuttle and school bus, urban transit, vocational and medium and heavy-duty truck and tractor applications. The engine is compatible with compressed natural gas (CNG), liquified natural gas (LNG), and renewable natural gas (RNG). Cummins announced the L9N at the end of 2016, and it replaced the Cummins Westport ISL G in Europe the following year. In North America, the ISL G and its 'Near Zero' counterpart have been replaced by the L9N in 2018.
The L9N uses a three-way catalyst which works by introducing a catalyst to convert the nitrogen oxides to nitrogen gas and oxygen gas, carbon monoxide to carbon dioxide, and hydrocarbons to carbon dioxide and water. The engine also features cooled exhuast gas recirculation (EGR), and spark-ignited stoichiometric combustion. The 2018 L9N is certified for EPA and CARB optional low NOx emissions standards of 0.02 g/bhp-hr, 90% lower than the previous standards.