Cummins X-series engine

The Cummins X-series engine, known as the ISX, is an Inline-6 diesel powerplant designed for heavy-duty trucks, motorcoaches, and off-road applications such as industrial machinery and marine use. Introduced in 2001 to replace the N14 due to EPA emissions regulations, it also has an off-highway variant called the QSX. The ISX offers various horsepower configurations, including a 650 hp model for recreational vehicles. Notable emission control technologies include cooled exhaust gas recirculation (EGR) introduced in 2002 and a diesel particulate filter (DPF) added in 2008. The latest version, the ISX15 CM2250, employs selective catalytic reduction with diesel exhaust fluid (DEF) to drastically reduce nitrogen oxide emissions. Additionally, the engine features a dual-fuel option that burns natural gas, achieving a 90% reduction in emissions compared to EPA standards. While earlier models used an anti-backlash gear system for reduced noise, newer versions like the ISX15 saw improvements in efficiency despite some friction loss. The Cummins Signature series, introduced in 1998, evolved through multiple generations in Australia and internationally, incorporating advanced emission control technologies over time.