Typical RPM scales

Typically an RPM signal from an ignition coil will need to be scaled to get an RPM in the form:

RPM = f x 60 x 2/cylinders

This is because input modules gives pulses per second which we need to convert into revolutions per minute.

e.g. 1 pulse per second = 60 pulses per minute x 2 (2 revolutions of crankshaft per combustion of spark plug) = 120 divided by the number of cylinders (4) = revs per minute (30).

So, for a four cylinder engine it would be 120 divided by 4 = 30.

Try the values in the table as starting points.