What is a Dyno? Short for Dynamometer, a dyno is any device used for measuring force and power. Dynos can work in very different ways, but TTRNO’s Dynojet Dynamometer determines horsepower (HP) by calculating a motorcycle’s rate of acceleration as the motorcycle’s rear wheel spins a 500 lb roller. After the HP of the motorcycle has been determined, the dyno’s computer can measure the RPM of the engine and use the equation, HP = (torque x engine RPM)/5252, to determine the torque.