Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: CHT/EGT selector switch?

  1. #1
    Birdseyeview's Avatar
    Join Date
    Sep 2017
    Location
    Oregon, Ill
    Posts
    198

    Default CHT/EGT selector switch?

    I've got the Rotax 912 supplied CHT senders already on the engine and haven't purchased any EGT probes yet. I've also got a Westach quad gauge which only monitors one CHT and one EGT at a time. Any recommendations on which cylinder I should monitor, or should I get a selector switch and monitor them all? Spruce has these switches and I could get one for all the CHT senders and another one for all the EGT senders. Also, what location in an exhaust pipe is best on the 912 for mounting an EGT probe?
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  2. #2
    Senior Member
    Join Date
    Apr 2009
    Location
    Chisholm Mn
    Posts
    1,562

    Default Re: CHT/EGT selector switch?

    I have one of those 4 position switches from ACS that you mention. You can actually use the same switch for CHT and EGT. As the switch comes, it has wires on only one side, but there are connections on the opposite side of the switch that you can connect to. That is what I did with my Avid Flyer with the 4 cylinder Jabiru engine in it. In # 1 position, I'm reading #1 cylinder EGT and CHT, in position #2, #2 cylinder EGT and CHT, ect, ect. I usually just leave it on #3 cylinder as that one runs the hottest. Once in a while I will switch through and look at what the others are doing. JImChuk


    PS I just went to Westach's site, and looked at that switch there. Looks like you can get the switch wired for the other 4 termanials from them (model 254-4FD) or just wire the cheaper model 254-4F yourself westach.com/products/ACCESSORIES/SWITCHES/SWITCHES%20FOR%20THERMOCOUPLES/index.php
    Last edited by avidflyer; 11-26-2018 at 08:59 AM.

  3. #3
    Birdseyeview's Avatar
    Join Date
    Sep 2017
    Location
    Oregon, Ill
    Posts
    198

    Default Re: CHT/EGT selector switch?

    Thanks for the info avid flyer. Just curious, do you have your selector switch mounted on the instrument panel near your associated temp gauge or somewhere else a little more out of the way since you don't use it often?
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  4. #4
    Senior Member
    Join Date
    Apr 2009
    Location
    Chisholm Mn
    Posts
    1,562

    Default Re: CHT/EGT selector switch?

    If I can post it, here is a pic of my panel. I use an MGL-E1 engine monitor for CHT and EGT and the 4 way switch is right below it. After much back and forth, I think I figured out how to reduce the size of the photos. The panel is not finished of course in this picture, but it does show the switch and such. JImChuk
    Attached Images Attached Images

  5. #5
    Birdseyeview's Avatar
    Join Date
    Sep 2017
    Location
    Oregon, Ill
    Posts
    198

    Default Re: CHT/EGT selector switch?

    I'm assuming that your MGL engine monitor only shows one cylinder at a time, and that's where the need for the rotary switch arrises. Now that you've had the ability to monitor all the cylinders for a while would you do it differently if you were doing it again? For instance and for simplicities sake, would you only monitor the temps on one cylinder and ignore the rest and eliminate the switch and a few temp probes? What's your take on the reliability of the switch? I saw someones comments in the Spruce catalog review that he had to replace his switch every 3 years. In your situation and set up do you worry more about CHT or EGT? I know this isn't exactly a fair comparison to my Rotax 912 but I'm trying to get at the underlying logic for what is important to monitor and what my options to display it are, while staying within the confines of my existing quad gauge. I also have an underlying goal of keeping my panel and wiring as simple as possible but a rotary switch would certainly be included if its function fulfills a key need.
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  6. #6
    Senior Member
    Join Date
    Apr 2009
    Location
    Chisholm Mn
    Posts
    1,562

    Default Re: CHT/EGT selector switch?

    I think it's nice to be able to see all 4 temps when you want to. I'm rebuilding a Kitfox that will have a 912 in it, and will maybe go the same route. I've never had trouble with the switch, actually I used to have 2 of them, one for CHT, and one for EGT. When I rebuilt the plane and panel, I learned I could use just one. The Jabiru may be a bit more finicky then the 912, so maybe monitoring all 4 cylinders is better with it than the 912. My monitor could see 2 EGTs and 2 CHTs at once, but I only use one side. Looks like all you would need is 4 EGT probes plus the switch, and this should work fine on your quad gauge. I would probably go with it. JImChuk

  7. #7
    Birdseyeview's Avatar
    Join Date
    Sep 2017
    Location
    Oregon, Ill
    Posts
    198

    Default Re: CHT/EGT selector switch?

    OK, thanks so much for your insight and advise. For your 912 install have you settled on which EGT probe to use? The clamp on type or would you weld a boss on each pipe for the NPT type attachment? Seems like the clamp on type is the easier install but the other may have some advantage.
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  8. #8
    Senior Member
    Join Date
    Apr 2009
    Location
    Chisholm Mn
    Posts
    1,562

    Default Re: CHT/EGT selector switch?

    My exhaust pipes already have the holes drilled in them, so clamp on is probably the way I will go. JImChuk

  9. #9
    Birdseyeview's Avatar
    Join Date
    Sep 2017
    Location
    Oregon, Ill
    Posts
    198

    Default Re: CHT/EGT selector switch?

    where are the holes drilled exactly and is it the same distance from the flange on each pipe? I assume you are going with a certain p/n clamp. Do you know which mfr and p/n?
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  10. #10
    Senior Member jiott's Avatar
    Join Date
    Jun 2010
    Location
    Portland, OR
    Posts
    2,960

    Default Re: CHT/EGT selector switch?

    Rotax 912 Installation manual specifies exactly where to mount the EGT probe in the exhaust header. I believe it is about 4" from the flange, but don't take my word, look it up. The recommend the two rear headers.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •