Abstract— In this paper, we first describe the dynamic properties of rubber parts of rubber damper pulley that are necessary for the modeling and numerical simulation of torsional vibration. Secondly, we describe an experiment in which two crankshaft pulleys with a torsional rubber damper pulley are fitted to a 6-cylinder, high-speed diesel engine. Torsional waveforms of the rubber damper inertia ring and the pulley are measured by means of phase-shift torsiograph equipment. The measured waveforms are harmonically analyzed and the dynamic properties of the torsional stiffness and the torsional damping are investigated from an experimental viewpoint. As a results of comparisons with experimental data, certain dynamic properties of damper pulleys with a torsional rubber damper have been clarified. The model used for the numerical simulation of the torsional vibration is a multi-degree-of-freedom equivalent torsional vibration system. The tension acting on the damper pulley and the rotational resistance of the alternator, the cooling water pump, the valve train system, etc., as well as the frictional resistance of other accessories, were considered. Moreover, as a numerical simulation method of the torsional vibration, a transition matrix method is adopted. The validity of this method has been confirmed from comparison and examination of measured values of torsional vibration and simulation values results.