The Busemann Advanced Concepts Lab at the University of Colorado Boulder has been researching improvements to small turbojet engines designed for unmanned aerial vehicles for the past three years. The BIOMITE senior design team has continued this tradition by designing adaptations for a commercial-off-the-shelf US Microjet AT-450 turbojet engine to run on a biofuel and increase its thrust-to-weight ratio. Sensitivity analysis was conducted to determine the areas in which to make thrust-to-weight improvements. The new engine is designed to incorporate a new combustor can, turbine stage, and variable area nozzle. Shapiro analysis was used to determine the combustor geometry needed to burn the biofuel at a higher temperature and deliver higher energy flow to the turbine stage. Frequency analysis of the new rotor was conducted to ensure safe operation after integrating the new commercial-off-the-shelf turbine. Since the engine operates at a higher temperature than originally designed for, the existing engine control unit was replaced with LabVIEW software. The engine was successfully run on synthetic-paraffinic-kerosene and demonstrated the predicted performance.