During the construction of the GRV-1 Turbotug, modifications were made to the GR-5 Turboshaft Engine. These modifications transformed the GR-5 into the self starting GR-5A turboshaft engine. Being completely constructed from “off the shelf” items, the 8 horsepower engine is like no other turbine. The home-built engine features an electric start, electronic control system, and an internal alternator to generate power to run the engines systems. A propane fuel source, external battery and starter switch is virtually all that is needed to run the GR-5A.