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
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?
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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
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.
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
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.
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
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?
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.