EGT probe/gauge help please.

[jackbombay]

I recall a discussion here about different EGT probes and how some are really sensitive (K type I'm pretty sure) to any changes in the wire that runs from the probe to the gauge, but there is also another type that is far less picky about the wire length.

   I need to install an EGT gauge in my westfalia and the longest set of wires that autometer makes for their EGT gauge is 10.5', not long enough. So what other options are there?

  Thanks!

[KTZed]

Here ya go
http://aircraftspruce.com/catalog/inpages/micro10egt.php

Theres a thread on here about the westach egt probes and gauges from aircraft spruce...sounds like the best/cheapest option to me. I have just ordered a setup myself!

[jackbombay]

Ah ha! I found this, this, and this, but that combo costs about $100 more than the autometer version I have purchased :-/

[jackbombay]

Here ya go
http://aircraftspruce.com/catalog/inpages/micro10egt.php

   Thats a lot cheaper than the ISSPRO bits and pieces!

   When I talked with autometer they were actually fairly rude about the fact that there is no way to make the leads longer tat they would stand behind. I already have the autometer though asI figured longer leads would be no big deal. I can sell the autometer to a friend that needs one for his sprinter, so thats not a big deal.

 If the gauge reads 50* off I wouldn't care much, but I'll have no way of knowing if its reading 50* off or 200* off  :-/

[saurkraut]

Libbybapa had a couple of miles of this lead wire on ebay a while back.  Try sending him an IM.

[TD_Bunny]

Just curious if you have looked at Dakota Digital for EGT gauge/Probe? they seem to have decent prices with a reasonable product but i dont know how they match up with the spruce or autometer.

[jackbombay]

Ah ha! I found this, this, and this, but that combo costs about $100 more than the autometer version I have purchased :-/

  Ahh, the amplified gauges can use regular old copper wire :-)

  And according to David Marshal the difference in resistance is so small between the official lead wire and plain old copper wire that its irrelevant, I'll measure the resistance between the 8.5' of lead wire I have an 20' of plain old copper wire and go from there.

[Baxter]

I think the jist of it was..

So long as you used EXACTLY the same wire and EXACTLY the same connectors and the wires were EXACTLY the same length, and when crimping the wires didn't protrude from the terminal and tough the toher wires then you are pretty much okay.

It's something to do with how the thermocouple works, junction of 2 metals? and basically if you solder, thats a big no no, but using the same crimps is okay as they cancel each other out, or something.

[Baxter]

Oh, and the UK's Aircraft Spruce type place is Airworld UK, they just send you any old electrical flex as an extension for their thermocouples.
just to add to the conundrum.
 :lol:

[Baxter]

:lol:
I think I'll just buy a fast car, already done!
All this is making my head hurt!
 :lol:

[jackbombay]

Well, I checked the resistance of copper wire to the resistance of the 2 wires that came with the EGT gauge and they were way different, which is completely meaningless, but it was enough to make me order the ISSPRO gauge so I don't have to worry about it at all, accurate for sure, $50 more than the autometer and I can sell the autometer one easily enough.

  Thanks for the advice guys!

[jauguston]

The Isspro gauge doesn't care how long the wire is. I have 48' of wire to the sender on my motorhome. I called them and they said just use 18ga copper wire and you are good to go.

Jim

New member installing a 1.6 TD in my '87 Samurai.

[jauguston]

What research would be more reliable than the telephone discussion I had with the tech support person at Isspro?? Please don't tell me to see some opinion of a self-appointed internet expert.

Jim

[jauguston]

Andrew,

I am a little bit confused by your response. Are you trying to say that the tech support person at Isspro gave me wrong information? Some long class A motorhomes have Isspro thermocouple wires up to 55' long and they work fine. I have three of their pyrometers  each with different length wires to the thermocouple and all work fine. I consider Isspro to be a very good product and have quite a few of there instruments.

I am always willing to learn.

Jim

[Vincent Waldon]

 Are you trying to say that the tech support person at Isspro gave me wrong information?

If they told you to use any old 18ga wire as an extension, then yes, IMHO, they are wrong.... assuming they were talking about extending between the thermocouple and the amplifier (my ISSPRO has an amplifier).  If they were talking about between the amplifier and the gauge (the four wires) then they are correct.

Here's what a typical manufacturer of thermocouples has to say on this subject;

If you need to increase the length of the leads from your thermocouple, you must use the correct type of thermocouple extension wire (eg type K for type K thermocouples). Using any other type of wire will introduce a thermocouple junction. Any connectors used must be made of the correct thermocouple material and correct polarity must be observed.

(taken from http://www.picotech.com/applications/thermocouple.html which is a great one-page primer on how thermocouples work and design considerations when using them).

Perhaps the guy on the phone was thinking about the amplifier wires, or perhaps was misinformed, or uninformed.... after all, he's in the gauge business rather than the thermocouple business.



Vince