Hi Larry,

The RPM sensor senses any ferrous (iron based) material. You do not need to use a magnet. For Brake dynos, a simple bolt or two will do, and I don't recommend anything more fancy. Stay with max 2 pulses per revolution. The electronics is just counting pulses and dividing by the number of pluses entered in "Options" to calculate the RPM. The bolts need to come within 2mm proximity of the sensor. 

For Inertia dynos you need a very accurate trigger wheel, but no need for brake dynos.

Cheers,
Jostein

I have been working with Brian Lowery on setting up a land sea water brake and a your dyno. Please let us know the recomended wheel to energize the gear tooth hall effect pick-up for the RPM input, would it be a missing tooth sprocket or a aluminum wheel with a metal insert ,or a magnet insert ?

Larry