Discussion and questions related to the course How to Degree a Cam
Why it appear the "power" as first cycle isn't supposed to be the Intale cycle the first? Or just showing the cycles depending of the crank rotation?
You're correct, the cycle starts with the intake. I expect the reason some use the power stroke to start the cycle is because we are concerned with the ignition timing which is related to the same TDC the power stroke 'starts' on.
It really doesn't matter where we start drawing the 4 cycles of the process. We've drawn it starting with the power stroke as it makes it easier to visualise the valve opening and closing events which then occur in the centre of this drawing. It's a continuous cycle though so just keeps repeating.