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Hello everyone, this is my first post here, but been lurking for a while. I tried to search this topic but drew a blank so it here it goes:

I have a 914 and an EIS 4000 with provisions for 4 CHT sensors which I would like to take advantage of. Where are you all putting your CHT terminals/probes/etc. To me it looks like the spark plugs is the only way for me to go but I was wondering if there were other locations I could take advantage of and still get accurate results such as the bolts holding the cylInserts on etc.

Thanks in advance! Josh
  • Re: 4 CHT sensor location

    by » 6 years ago


    See section 12.4(Page 47) of the 914 Installation Manual.

    The location of the measuring port changed depending on which version of the cylinders you have, and the temperature differs by 15°C.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.


  • Re: 4 CHT sensor location

    by » 6 years ago


    The "old" style had two probes. Each probe measured the temperature of the aluminum head, one probe on each side of the engine. The actual goal was to measure the temperature of the coolant, since coolant boiling is the main concern.

    The "new" style also uses two probes, one on each side of the engine. The difference is that the new probes directly measure the temperature of the coolant.

    Because the heads are water cooled, I can't see any benefit of monitoring all four CHTs. Because they are flooded with liquid coolant, their temperatures should be very close to one another. This is in contrast to cylinders that rely on air cooling only, where you can get big differences in CHTs.

    At least that's my take, but remember that I am a Rotax newbie.

  • Re: 4 CHT sensor location

    by » 6 years ago


    I don't see any real benefit to using all 4 CHT's either.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: 4 CHT sensor location

    by » 6 years ago


    I have read that the "under the plug" style probes can be finicky and subject to errors. I would much rather have two accurate readings than four questionable ones.

  • Re: 4 CHT sensor location

    by » 6 years ago


    Thanks for the replies everyone. I’m sure this is blasphemy but I have an after market injection setup so I want 4 CHTs as I’m programming the mixture by each cylinder. I will also have a coolant temp gauge.

    Bill I have the left style with the upside down probe.

    Thanks again!

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