1)    Intake stroke occurs; a mixture of both air and gasoline are drawn into the engine (5 – 1)
                           
                   2)    Compression stroke occurs; pressure and temperature increases through an adiabatic process (1 – 2)

                   3)    Combustion occurs via the spark plug igniting the fuel; volume remains constant in this stage (2 – 3)

                   4)    Power stroke occurs; adiabatic expansion process (3 – 4)
 
                   5)    Valve opens to exhaust waste gas (4 – 5)

                   6)    Exhaust stroke; piston moves back to push any remaining waste gas out of the engine. (1 – 5)
                                                   Otto Cycle diagram that shows the different process and the change in Pressure and Volume during those processes.