The L9N is the natural choice in alternative-fuel engine technology. With industry leading performance, it combines all the advantages of clean burning, low cost natural gas with “no compromises” in power and torque. The L9N  is an upgraded evolution of the proven ISL G, moving to the latest Euro 6 Phase D emissions with minimal changes retaining the impressive low-end toque, transient response and quiet operation for bus and truck applications.

The L9N engine block is shared with the Cummins L9 diesel – a full skirted block for increased rigidity and strength. The design provides superior piston ring and bearing life, improved coolant flow and targeted piston cooling, for greater reliability and superior durability. The engine’s life to rebuild and rebuildability are similar to those of diesel engines. The 8.9 litre L9N uses advanced stoichiometric combustion with cooled Exhaust Gas Recirculation (EGR) to meet ultra-low emissions requirements. The cooled-EGR system takes a measured quantity of exhaust gas and passes it through a cooler to reduce temperatures before mixing it with fuel and the incoming air charge to the cylinder. This lowers combustion temperatures and knock tendency, reducing engine out emissions and noise. With a pedigree of millions of engines to date, Cummins cooled EGR technology is proven in a wide range of installations.

Stoichiometric combustion is the ideal combustion process where all fuel and oxygen is completely consumed. This means that no unburned fuel or oxygen exits through the exhaust. Combined with cooled EGR it improves power density and fuel economy to create a high performance natural gas engine. It also enables the use of simpler, lower cost exhaust aftertreatment systems. Compared with previous Cummins lean-burn natural gas engines, L9N torque at idle is improved over 30 percent, and fuel economy is improved by up to 5 percent.