Products for exactly this sort of monitoring exist and are marketed as digital engine monitors. I have one fitted to my Enstrom which monitors and records the following parameters.
Engine rpm, individual cylinder head temps and exhaust gas temps, fuel flow, manifold pressure, OAT, oil temp. All sorts of sensors can be bolted on to theses devices. Overspeeds and overtemps are recorded. It cost me £1500 plus fitting.
It has an STC for most aircraft types.
See:
http://www.buy-ei.com/EI_Mux-8A_Data_Recorder.htm