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This paper describes an experimental study to determine the potential for fuel efficiency improvements offered by dedicated, high compression E85 engines with optimized powertrain calibration strategies. The study involved a prototype variable fuel engine that could operate using either gasoline or E85, and a high compression version of the same engine that was suitable only for E85. Fuel consumption and engine-out emissions were evaluated using steady-state engine dynamometer tests to represent urban and highway speed/load conditions. For each fuel and engine combination, the fuel efficiency and emissions trade-offs provided by varying Exhaust Gas Recirculation (EGR) levels were determined. For the high compression engine, operation at lower speed/higher load conditions (producing the same power as the standard speed/load settings) was also investigated.

This paper describes an experimental study comparing the peak ignition voltage requirements of natural gas and gasoline in a typical bi-fuel vehicle application. Chassis dynamometer tests were carried out in which the vehicle was subjected to different types of transient wide open throttle events to create “worst case” voltage requirements. In addition to measurements of ignition voltage, other factors known to influence voltage requirements (such as cylinder pressure, electrode temperature, and fuel/air ratio) were recorded during the transient tests in order to obtain a better understanding of the underlying reasons for observed differences in voltage requirements between the two fuels and between the different transient test procedures. The results presented in this paper quantify the increased peak voltage requirements (relative to gasoline) for reliable ignition of natural gas under various operating conditions.