monitor
Message text written by "William S. Stewart"
>Although I was told it was totally compatible with the Rotax 914 when I
bought it, I found out differently later. It is not compatible with the
Rotax oil pressure, oil temperature and CHT sensors. Oil pressure can be
used if you substitute their sensor for the Rotax one. However oil
temperature is a lot different, they want you to make a sensor out of
parts, and drill a hole in the engine to put the sensor in. They recommend
a ring thermocouple for CHT (the kind you put under a spark plug), which
seems to work okay, but Rotax does not reccomend it. I ended up with
separate mitchell guages for oil temp, oil pressure and CHT, using the
Rotax sensors. CHT is also monitored by the RMI using thermocouple, which
provides alarming for hi temps. This also provides monitoring of the most
critical engine parameters in case of failure of the RMI.<
For oil temperature I drilled out the insides of the Rotax sender from the
top and mounted the new sender inside. If the drilling is done carefully
the spring inside the original sender can be saved to protect the wires of
the new sender as they exit the body of the original. As the inner body of
the original is preserved there should be no risk of leaks or damage.
For CHT it is possible to buy a probe sender from Omega Engineering (as
recommended by RMI) with an adapter for 1/8" NPT thread. The only
difficulty I found was obtaining an adapter from 1/8" NPT to the Rotax
metric size. In the end I got a local engineering shop to make me one up.
Using the original sensing position ensures that the measured temperature
equates to the figures quoted by Rotax. This will be different to the
temperature at the plug as one measures water temperature and the other
head temperature.
>RPM works fine with the 914 using the RPM leads from the turbo
controller,
but I don't know how you would do this with the 912. I suspect that using
the method described in the RMI manual would not work.<
When I contacted RMI about this they passed on to me the following
solutions found by other users:-
- - -"ROTAX 912 Engine:
Vic Syracuse says he had hooked up 3 912s and only changed R3 to 100k. All
worked great. Another cust said this works! Meryl Williams used 1k and set
at position 4!
Dan Billingsly (334) 793-1343 used diode (ECG552, although I think
anything is ok) in connecting to tach output with band towards
monitor. Then he changed R3 to 10k and paralleled CR1 with a 27k.
He used a scope and said this gave best, cleanest and most stable
waveform. Use his as a last resort before using Hall effect sensor."- - -
- - -
I hope to run my engine for the first time in the next few months. I will
report back with my findings.
Regards
Nigel Charles
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