I have a sensor question & have never received a satisfactory
answer.

     For my build, I have the RWS EM2 as the primary system reporting
engine
     parameters.  Because I am a computer professional, I also have good
old
     fashion analog gages for several of the critical readouts as well
-- I
     don't know enough about the EM2 failure modes to completely trust
it
     when the chips are down & have seen too many nifty computer-based
     systems go belly-up.  Call me a pessimist.

     My question is: can I wire the electronic (EM2) and analog gages in
     parallel from any single sensor, (e.g., oil temp; oil pressure;
water
     temp; water pressure) or must I double-instrument the engine such
that
     each sensor serves a single monitor?  My belief is that I must
double
     instrument the engine (2 oil pressure sensors, etc) -- I believe
that
     wiring sensors in parallel would result in but gages reading
     incorrectly.  If I do double-instrument the engine, I will have the
     conundrum of determining what to do when the EM2 and analog gages
     disagree.  Not terribly worried about this, but more workload
     nonetheless.

     Mark Supinski

     I think this is question Tracy Crook needs to answer.
     However my guess is Tracy's inputs are high impedance voltage
inputs.
     There fore you should be able to connect analog gages in parallel.
     Depending of course on the input impedance of the analog gages you
     are using. I could be wrong.

     In the case of a resistance type sensor I think the current
originates
     in the analog gage. If Tracy's unit also supplies current there
could
     be a conflict. I could be wrong.

     Paul Lamar

I never really got a straight answer on this from Tracy -- thus my
throwing it open to the group.

As a defensive measure, I ran enough wire to double the number of
sensors.  This will let me install the tank & plumbing w/o worrying
about having to undo it all to add more engine sensor wiring.

Worst case, I plan on trying it & seeing what happens on a sensor by
sensor basis.  My big concern is that I somehow fry something by doing
this.

Mark Supinski


After thinking about it for a few hours I would install dual sensors.
Use the ones that come with the mechanical gages. That way you have a
completely
redundant system and can cross check. You might have to built some T
blocks
in some cases so you can mount two sensors in the same hole.

If it were me I would forget the electronic gages entirely unless
you had data acquisition and needed the sensors for that or for the EFI.

No beating a bunch of mechanical gages that will keep working no matter
what.

Paul Lamar ...No rotor no motor.

Mark/Paul,
I went with dual sensors.  If you look at the water pump in my picture,
you'll see two temp sensors and one pressure sensor.  One temp sensor
goes to the EM-2, the other to the EFIS-1.  Or, you can use them to
determine delta T for your oil/water coolers, which is what I did on my
oil temp sensors.  I used a special adapter fitting so I can move the
sensor easily for simplified cooling system diagnosis.  I like having
redundant gauges.

Mark S.



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