STEALTH DYNO™ VEHICLE PERFORMANCE DATA LOGGER Stealth Dyno was a small battery-powered data logging unit that monitored and recorded speed, RPM, and other types of vehicle performance information. A companion computer graphics program was also provided to evaluate performance gains. Alternative forms of the device were used to monitor various functions on large stationary equipment in manufacturing facilities and on inertia-based engine dynamometers to provide horsepower and torque profiles.