In this paper, we proposed an estimation model for the Indicated Mean Effective Pressure (IMEP) which means the generated torque by the combustion with using only a single cylinder pressure sensor. The IMEP of each cylinder leads the rotational crankshaft acceleration. Based on the rotational dynamics, we can determine an empirical model structure between IMEP and crankshaft acceleration to estimate the IMEP of an individual cylinder. The proposed model calculates the IMEP of an individual cylinder by applying the IMEP obtained from a single pressure sensor and crankshaft acceleration. Consequently, the proposed estimation method can be used for combustion control with cost affordable equipment. In addition, it is beneficial for a real-time system because the calculation time of IMEP of other cylinders can be eliminated. The proposed model is validated through the engine experiment.