Source and Installation For CHT/EGT W/ Six-Position Switch

[jyl]

I'm thinking about installing a single CHT gauge and a single EGT gauge in my car, with probes on all six cylinders (sparkplug washer and probe in heat exchanger tubes). I would like to use a single rotary switch to select the cylinder to read on both gauges. So switch position #1 would give me CHT and EGT on cylinder #1, position #2 would give me cylinder #2, and so on.

What sort of switch do I need? Asked another way, what is the description that I should look for in "switch catalogs"? I'm vaguely thinking I need a "dual pole" switch. Any good sources to recommend?

Do the wires from the CHT and EGT gauges have to be installed and routed in some particular way? I hear them called some special "thermocouple" wire. Can I simply bundle them together in the engine compartment. find some way to route them through the rear bulkhead and on to the switch, cut to length and solder to the switch and then use regular electrical wire to connect switch to gauge?

I guess the problem really is, I'm unclear how the CHT and EGT gauges get readings from their respective probes.

[jyl]

Sorry, I should have done some more research before posting. I went to egauges.com and read the installation instructions for the VDO CHT and EGT gauges. The CHT gauge requires two leads from the probe, the EGT gauge also requires two leads from the probe, so the switch in my idea would have to be switching four circuits at once. I'm not sure such a thing is easily found at all.

[350HP930]

Omega is your friend . . .

http://www.omega.com/techref/

http://www.omega.com/guides/thermocouples.html

http://www.omega.com/toc_asp/subsectionSC.asp?subsection=H10&book=Temperature

http://www.omega.com/ppt/pptsc.asp?ref=DP1000&Nav=temm06

For what you want to do the scientific instrumentation route would be a bit more practical than anything an auto instrument manufacturer can provide.

[Joeaksa]

Also:

http://www.aircraftspruce.com/catalog/inpages/alcor_egtchtsys.php

http://www.aircraftspruce.com/catalog/inpages/westcombos.php

[jyl]

Does anyone have photos of the square aircraft-style gauges installed in a 911? I wonder if it looks okay.

Alternatively, I guess I could buy the switch and probes from aircraftspruce and try to use them with a VDO gauge.

[RoninLB]

old pic.. It's not a necessary line of sight instrument for my act. I know when driving is getting warm, then I'll pay big attention.

[RoninLB]

Originally posted by jyl

Do the wires from the CHT and EGT gauges have to be installed and routed in some particular way?

the EGT probe install is slow and tiedous. The extended wires should be pre-planned if you want to route the wires under or on top of the engine sheetmetal. Then you have to work around the exhaust stud nuts for a socket. Then you have to figure being able to turn the screw on the probe clamp. It's not a wham bam by any means for a clean install. I used silver solder and Deutsch connectors. They should be able to be disconnected for engine drops.