The study of dynamic performance of new patented Torsional Vibration Damper for an engine crankshaft is presented. Design and structure of Torsional Vibration Damper is based on author's US Patent 7,438,165 having the control system with instantaneous frequencies tuner which allows implementing exact tuning strategy for all frequencies in running engine. The same scheme would apply for a design of perfectly tuned Flywheels which could successfully replace the conventional and dual mass flywheels. A description and structural details of proposed solution are shown. Mathematical model based on the system of second order differential equations and experimentation techniques have been used for establishing of the dynamic behavior of engine crankshaft system. Main attention is paid to mitigation of the torsional vibrations; some suggestions are made for elimination of the variations of instantaneous value of rotational speed and coefficient of fluctuation of rotational speed. Tests have been conducted in order to get objective metrics and compare the dynamic performance of new device to dynamic data of existing rubber and viscous torsional vibration dampers used in front engine accessory drive systems. Automobile diesel engine set was selected for experiments. Test results obtained from experiments and mathematical simulations illustrate the effectiveness of the proposed tuned Torsional Vibration Damper. The acceptable in automotive industry magnitude of torsional vibration peak - to - peak twist angles is 0.4 degrees. The tested prototypes allowed reduce this number to 0.15 degrees.