The objective of this project was to successfully develop and certify an LPG-dedicated medium-duty original equipment manufacturer (OEM) engine that could be put into production. The engine was launched into production in 1994, and more than 800 B5.9G engines are now in service in the United States and abroad. This engine is now offered by more than 30 Bus and truck OEMs. | Cummins Engine Company B5.9 Propane Engine Development Certification And Demonstration Project by National National Renewable Energy Laboratory (Nr