Abstract: Substantially instantaneous, sub-cyclic speed of an internal combustion engine provided by clock counts between successive sensing of integral numbers of teeth on the flywheel of the engine provide plural speed indications within each cylinder stroke engine sub-cycle, which are utilized relative to each other, without conversion to speed dimensions, to determine dynamic, sub-cyclic operating parameters of the engine, such as relative power contribution of the individual cylinders of the engine.

Abstract: Indications of speed of an internal combustion engine are derived from an engine member connected to and rotating directly with the crankshaft, such as the teeth on the fly-wheel, so as to provide indications for speed measurements on a sub-cycle basis (that is, many times during each revolution). Sensing of an integral number of subsequent indicia, such as teeth, starts and stops an interval counter, such as a clock, having a frequency much greater than the frequency of indicia sensed, feeding a counter; for each integral number of indicia, the counter provides a manifestation of the time lapse between the indicia, and therefore the time to rotate through the small angular increment of the indicia spacing. The ratio of the integral number, which may be one or many, to the total number, times the ratio of the counter accumulation to the clock frequency, provides a measure of speed in speed dimensions of revolution per unit of time.