Torsional vibrations are inherent in the operation of reciprocating machines, which is one of the leading causes of mechanical failures. This work analyzes the torsional vibration attenuation of a crankshaft of a single-cylinder reciprocating compressor when identical resonators are attached. The shaft is modeled by a continuous nonlinear system, considering the inertia variation of the crank-slider mechanism with rotation and under a concentrated harmonic excitation. Two main configurations are presented, without and with resonators. At first, the nonlinear and linearized systems are compared for two different crank length values. Results show that the systems present similar behaviors for a low value of the crank length. On the other hand, when the crank lengths are raised, the resonance frequencies are slightly shifted backward and the response exhibits nonlinear effects. The second case presents the system response when the resonators are attached. The performance of the resonators is evaluated for two crank length values as in the previous analysis. In both cases, the resonators can reduce the vibration amplitudes in the neighborhood of the target frequency, even when the nonlinearity is increased in the system response.