Efficient operation of a hybrid-electric propulsion system (HEPS) powering a small remotely-piloted aircraft (RPA) requires that a controller have accurate and detailed engine and electric motor performance data. Many small internal combustion engines (ICEs) currently used on various small RPA were designed for use by the recreational hobbyist radio-control (R/C) aircraft market. Often, the manufacturers of these engines do not make accurate and reliable detailed engine performance data available for their engines. A dynamometer testing stand was assembled to test various small ICEs. These engines were tested with automotive unleaded gasoline (the manufacturer\u27s recommended fuel) using the dynamometer setup. Torque, engine speed and fuel flow measurements were taken at varying load and throttle settings. Power and specific fuel consumption (SFC) data were calculated from these measurements. Engine performance maps were generated in which contours of SFC were mapped on a mean effective pressure (MEP) versus engine speed plot. These performance maps are to be utilized for performance testing of the controller and integrated HEPS in further research. Further follow-on research and development will be done to complete the goal of building a prototype hybrid-electric remotely piloted aircraft (HE-RPA) for flight testing. Minimum BSFC for the Honda GX35 engine was found to be 383.6 g/kW hr (0.6307 lbm/hp hr) at 4500 RPM and 60% throttle. The Honda GX35 was overall the better fit for incorporation into the HE-RPA
