|In this study, the standard Otto cycle is reconsidered, leading to the replacement of its reversible adiabatic processes by polytropic processes. Two models were proposed, the sub-k polytropic model and the super-k polytropic model, in order to account for the losses encountered in the real Otto engine. The performance characteristics of the Otto engine were presented via plots of power vs. efficiency curves. The results, based on the two models, predict a slightly higher than 30% reduction in the net power output. The results also show that the efficiency of the real Otto engine lies at approximately 70% of the efficiency obtained from the standard Otto cycle. The current studyâs value is generally educational, and may also serve as guidance for engineers performing detailed simulations or conducting expensive experiments in the field. [Huleihil M, Mazor G (2012) Irreversible Performance Characteristics of Air Standard Otto Cycles with Polytropic Processes].