EGT probe too long??

Submitted: Monday, May 21, 2007 at 18:13
ThreadID: 45722 Views:3146 Replies:2 FollowUps:0
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Hello all,
Just bought a EGT gauge, but the probe seems to me a bit long, are you supposed to cut them to length?? or push the probe all the way in?
Your thoughts please.
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Reply By: Member - DOZER- Monday, May 21, 2007 at 18:35

Monday, May 21, 2007 at 18:35
The idea is to push it in and expose the last 5mm of it to passing gas, this joint inside is what takes the temp...dont shove it all the way in but 5mm exposed...when in situ, there is alot of exposed length but that is normal...
Andrew
AnswerID: 241433

Reply By: Ian from Thermoguard Instruments - Tuesday, Jun 05, 2007 at 09:17

Tuesday, Jun 05, 2007 at 09:17
Dozer is right in that only the tip of the thermocouple sensor needs to be in contact with the exhaust gas to make a valid measurement but I suggest a little more of the probe be exposed.

I like to see the probe extend about 15 to 20 mm beyond the inner wall of the manifold or exhaust pipe. This is to ensure the tip is out in the turbulent gas stream and not subject to any wall effects. It also negates heat loss through the probe sheath to the compression fitting/pipe wall.

Definitely don't push the probe through until it touches the pipe wall on the opposite side, as this will give low readings. Also, I don't recommend more than 20mm or so of exposed probe, as the longer the unsupported length of probe, the greater the chance of resonant vibrations at certain rpm which could lead to fatigue failure of the fine internal wires over time (not very likely but a possibility).
AnswerID: 244825

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