This Ultra-Low Carbon Powertrain project report describes the design, development, and testing of a prototype powertrain concept fueled by E85 ethanol and targeted to decrease CO2 emissions on a full-fuel-cycle basis by over 50 percent. This project developed a downsized 2.8L engine for use in class 4-6 medium-duty vehicles with power and torque capabilities appropriate for this market. A stop/start system was integrated with an automatic transmission to reduce idle fuel consumption. This project demonstrated that an E85 engine with a close coupled 3-way catalyst is feasible for delivering 2010 criteria emissions levels allowing for a cost competitive platform. System analysis, test cell testing, chassis dynamometer testing, and full vehicle demonstration were used to predict and quantify the results. A peak engine brake thermal efficiency of over 42 percent was achieved which enabled equivalent fuel economy to a gasoline powertrain and equivalent fuel cost to a diesel powertrain. This project concluded that over 50 percent CO2 reduction was achievable on cellulosic biofuels relative to currently available gasoline and diesel vehicles. Recommendations for future work were made to increase the level of field demonstration or examine next steps for improved powertrain efficiency using this E85 powertrain concept as a starting platform.
