Cummins Inc. has announced a 2017 L9 and a 2017 B6.7 hybrid engine for the transit market. Under the SmartEfficiency initiative, these engines focus on improved uptime, lower Total Cost of Operation (TCO) and better fuel efficiency.
L9 ready for transit bus applications
Available in 2017, the L9 for transit applications will continue to use the modular aftertreatment architecture. "The transit duty cycle provides unique challenges in creating consistent exhaust temperatures required for passive Diesel Particulate Filter (DPF) regeneration. Therefore, Cummins will continue to leverage the current product experience and Particulate Matter (PM) storage capacity of the Modular Aftertreatment System. This decision is consistent with the SmartEfficiency initiative and Cummins commitment to improving uptime and reliability," said Laura Chasse, Cummins general manager of North American Bus.
Another SmartEfficiency driven improvement is the isolated coolant loop for transit buses using an L9 powertrain, which improves reliability and reduces downtime. A water-to-water heat exchanger will be mounted on the L9, and will provide heat to the passenger compartments, as needed, while providing a self-contained coolant flow to the engine compartment area. This new approach reduces potential coolant leakage or air infiltration for better Exhaust Gas Recirculation (EGR) cooler reliability and durability.
B6.7 offers up to 5 percent higher fuel efficiency
Starting in January, 2017, the B6.7 hybrid engine system will use the Single Module aftertreatment system. The Single Module aftertreatment in B6.7 hybrid transit applications provides up to a 70 percent reduction in space claim, reduces weight by up to 30 percent, and provides better heat management and retention for improved fuel economy. The B6.7 hybrid system operates at consistent engine speeds and temperatures, providing a perfect match for the application of the Single Module aftertreatment system.
In transit applications, the B6.7 hybrid system provides up to 5 percent fuel economy improvements compared to the 2013 ISB6.7 hybrid. This is a result of an enhanced VGT Turbocharger, reduced friction, and better thermal management. The B6.7 hybrid is currently available with a 280 hp, 660 lb- ft torque rating.
Building off of the ISB's proven lineage, the 2017 B6.7 has made several system enhancements, providing reliability and uptime improvements. The variable geometry turbocharger (VGT) is leveraging the proven heavy-duty bearing system for better VGT reliability. Additionally, the B6.7 incorporates a Stage 1 NanoNet fuel filter for better water separation.
