The Otto cycle consists of isentropic compression, heat addition at constant volume, isentropic expansion, and rejection of heat at constant volume. In the case of a four-stroke Otto cycle, technically there are two additional processes: one for the exhaust of waste heat and combustion products at constant pressure (isobaric), and one for the intake of cool oxygen-rich air also at constant pressure; however, these are often omitted in a simplified analysis. Even though those two processes are critical to the functioning of a real engine, wherein the details of heat transfer and combustion chemistry are relevant, for the simplified analysis of the thermodynamic cycle, it is more convenient to assume that all of the waste-heat is removed during a single volume change.
the otto cycle consists of isentropic compression heat addition at constant volume isentropic expansion and rejection of heat at constant volume in the case of a four-stroke otto cycle technically there are two additional processes one for the exhaust of waste heat and combustion products at constant pressure (isobaric) and one for the intake of cool oxygen-rich air also at constant pressure; however these are often omitted in a simplified analysis even though those two processes are critical to the functioning of a real engine wherein the details of heat transfer and combustion chemistry are relevant for the simplified analysis of the thermodynamic cycle it is more convenient to assume that all of the waste-heat is removed during a single volume change