[Cupcar]

It is interesting that the Variocam ECU has to keep track of both the left and right side cams to make sure they are precisely in sync with each other as well as in sync with the engine cycle.

To do this there are 2 Hall sensors on the street engine, one for each intake cam, and the street cams each have Hall sensor discs on them that have 4 tits, each different in shape, giving 4 unique pulses per cam revolution, thus both engine cycle and cam position can be very precisely monitored and controlled.

On the other hand, my racing Cup cams, built for use without Variocam, only have a Hall disc with one tit on it.

This is because, since the camshafts are fixed, the race engine only needs a sync signal for engine cycle from the Hall sensor and thus also only uses a Hall sensor on one camshaft getting a single pulse signal per camshaft revolution.