ca 5 216 u00b0 ca the four stroke operation graphically illustrated in fig3 a is not explained herein since this mode of operation is readily known to one skilled in the art the six stroke operation graphically illustrated in fig3 b requires 216 u00b0 ca between firing of the individual cylinders 2 as noted above therefore starting with the first cylinder at 0 u00b0 ca the next ignition must take place at 216 u00b0 ca this can be accomplished by igniting the third cylinder illustrated in fig3 b with a dot on the sinusoidal line it can be determined that ignition takes place at 576 u00b0 ca 4 u00d7 144 u00b0 ca however by igniting 360 u00b0 ca earlier which is also a top dead center event the 216 u00b0 ca criteria is achieved the next ignition must take place after 432 u00b0 which can be achieved by igniting the fifth cylinder it can be calculated that 432 u00b0 ca 3 u00d7 144 u00b0 ca is the angle when ignition takes place the remaining steps consist of the same algorithm i e every second firing event or non synchronous firing event the necessary criteria are achieved for a cylinder located 360 u00b0 forward or backward as illustrated in fig3 b can be moved these 360 u00b0 and every other second firing event a synchronous firing event i e the required criteria are achieved for a cylinder at.