The study of dynamical performance of new Flywheel for any type of engine is presented. Design and structure of proposed Flywheel is based on George Nerubenko US Patent 7,464,800 having the control system with instantaneous frequency tuner and variable damping device adjusted for all operational frequencies in running engine. The patented scheme would be applied for a design of Flywheels successfully replacing the conventional and dual mass flywheels. A description, structural details and mathematical model of considered Flywheel are presented. The model based on the system of differential equations describing the rotation and vibration of mechanical components combined to Coulomb dry friction equations reflecting the contacts in variable damping device has been used for the analysis of the dynamic behavior of engine crankshaft system having proposed Flywheel. The analysis is presented for semi-controlled version of Tuned Flywheel equipped with variable damping device. The presented solutions are allowing be concentrated on a reduction of the variations of instantaneous value of rotational speed (angular velocity) forcing the elimination of a coefficient of fluctuation of rotational speed. Tests have been conducted for a comparison of the dynamic performance of presented Flywheel to dynamic data of conventional and dual mass flywheels. Test results of prototype of Tuned semi controlled Flywheel equipped with variable damping device show the reduction of a coefficient of fluctuation of rotational speed to 0.004 which is lower than required bottom level.