dave-in-nj:
in a very general way, the UNO/ NANO / Pro Mini are the same processor with almost the same number of pins.your need to have an event at some speed is a beginner application and should be satisfying for you to achieve.
EDIT:
I was wrong, the rpm sensor that is already mounted has a magnetic pick up signal. This is the only thing the engine dyno manual says about it.
However, do i have to adapt such sensor signal or is it possible to directly connect it to the Arduino board?