CHT/EGT selector switch?

[avidflyer]

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

[Birdseyeview]

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.

[avidflyer]

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

[Birdseyeview]

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?

[jiott]

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.

[Birdseyeview]

Jim, Thanks for pointing me in the right direction. I found the location of the EGT probe on page 10.1 of the Rotax 912S manual and the distance from the flange is stated as 2.76". It doesn't seem to say anything there about which cylinders to monitor. On page 21.1 of the installation manual it does mention that CHT should be monitored at cylinders 2 and 3 (one in front and one in back), in which both ports have a temp sensor installed. However, there's a CHT sensor port location on every cylinder head so this gets back to the basic question on what everyone is doing with CHT and EGT monitoring - Is the most common practice and/or recommendation to monitor CHT and EGT on all cylinders or just specific ones (#2 and #3)?

[Rodney]

The EGT probe is a type K thermocouple

Vktech 2M EGT Thermocouple K Type Temperature Probe Sensors Exhaust Screw Threads New
by Vktech

These are available on Amazon for about $18.00. I welded a 1/8" boss to the exhaust pipe and installed two on my engine. Plenty of cable to reach inside to the back of the instrument panel.

Regards
Rodney