On Aug 11, 2010, at 9:40 PM, Rotary Engine wrote:

>  Hi All,
> 
>  Has anyone thought through how to wire the stock RX8 coolant
>  temp sensor to a Dynon GP Input? Any info on specifics of
>  the sensor is also appreciated.
> 
>  Thanks in advance,
>  --Kenny A.
> 
>  Do you have the instructions for the Dynon Kenny.
>  You need to know what kind of sensor it requires.
>  You also need a calibration curve for that sensor.
>  Resistance verses temperature.
> 
>  The ECT Engine Coolant Sensor in the RX8 is the thermistor
>  type.
> 
>  "Thermistors are thermally sensitive resistors whose prime
>  function is to exhibit a large, predictable and precise change
>  in electrical resistance when subjected to a corresponding
>  change in body temperature.  Negative Temperature Coefficient
>  (NTC) thermistors exhibit a decrease in electrical resistance
>  when subjected to an increase in body temperature and Positive
>  Temperature Coefficient (PTC) thermistors exhibit an increase in
>  electrical resistance when subjected to an increase in body
>  temperature.  Because of their very predictable characteristics
>  and their excellent long term stability, thermistors are
>  generally accepted to be the most advantageous sensor for many
>  applications."
> 
>  I am not sure if the RX8 is a PTC or NTC type. Use an ohm
>  meter and place it in boiling water. You can then calibrate it
>  and compare the calibration curve with the Dynon type.
> 
>  Paul Lamar
> 
> 
> Automotive ECT's are negative. The lower the temp, the higher the
> resistance.
> This allows less current to flow and the ECU "see's" higher voltage. This
> richens the mixture like a choke. As the coolant warms, the resistance
> gets
> less. The ECU see's less voltage, thus less fuel. On the ECU board
> there are
> resistors just before the terminal to the sensor. There is an internal
> take
> off for it to sample the voltage, between this resistor and the sensor.
> Test to your heart's content though.
> 
> Dale Davies
> 
> Dynon does not publish a spec for their sensors. Their GP sensor is the
> same as their oil temp sensor. If you bought the sensor package and have
> the oil sensor, compare it to the RX-8 for resistance vs temp.  If they
> are not the same, it is unlikely you will be able to rig to get accurate
> readings.
> 
> Victor
> 
> Thanks all, this is plenty to get me started. Attached is
> an excerpt from the installation guide. Looks like the
> right combination of voltage divider / gain and anything would work.
> 
> --Kenny A.
> 
> That is pretty blurry Ken. Can you scan it at higher
> rez?
> 
> Paul Lamar
> 
> 
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