Greetings,

I have an older 912UL I'm installing, and I'm in the process of planning the Dynon D-180 installation.   This is the first 912 I've installed, so I'm learning as I go.   I will install 4 EGT probes, and would like to have 4 CHT readings, but know the 912 only has two designated CHT locations.  My engine has the older style dry probe locations, which use a resistive temp sensor.  As I understand, you are typically supposed to monitor the hottest of the two, which will vary depending on the engine installation (tractor vs pusher).  I also understand that these CHT temps are really closer to coolant temp readings than traditional CHTs.  If any of that is wrong, please let me know. 

I will of course monitor the designated CHT locations, since there are specs for that.  I'm very tempted to also add ring type CHT probes for each cylinder.  In several past threads, I've seen statements such as "never use ring type sensors under the spark plug", but when someone asks why not, there is never an answer.  Is there really a reason not to use them, or is it just considered unnecessary? 

I'd rather over-monitor than under-monitor, so I'll likely try to add a real coolant temp as well. 

Thanks,

Rusty

  • Re: New to 912- CHT questions

    by » 5 weeks ago


    Rusty, there is cooled water rushing through your heads at all times, causing all of the heads to run at roughly the same temperature. The only things I can think of that you will gain by installing additional CHT probes are weight and complexity. (As a bonus you get extra build time.)


  • Re: New to 912- CHT questions

    by » 5 weeks ago


    I think the main thing to gain is peace of mind knowing that all 4 CHTs have some representation.  If we can assume that all cylinders do the same amount of work, meaning nothing has gone wrong, and we further assume that no hoses are plugged or kinked or passages blocked, then maybe there's no reason to monitor all 4 CHTs.  I'm sort of a data junkie, and it's valuable to me to be able to see that everything is as it should be.  I get that it's not considered mandatory, but it's desirable to me. 

    I just want to know why people say not to use the ring CHT.  Is there any harm in using them, or just because people don't think you need to? 

    Thanks,

    Rusty


  • Re: New to 912- CHT questions

    by » 5 weeks ago


    Because you end up with things like this and wonder what someone was trying to do???

    23733_2_IMG_20151212_133317401.jpg (You do not have access to download this file.)

  • Re: New to 912- CHT questions

    by » 5 weeks ago


     And this!

    23735_2_IMG_20151212_133622935.jpg (You do not have access to download this file.)

  • Re: New to 912- CHT questions

    by » 5 weeks ago


    I've used ring type sensors on a few engines in the past, and I've never managed to do that to any of them, so I don't anticipate that being a problem. 


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