EGT

[Tom Cloud]

Greg, thanks .... I am quite familiar with thermocouples
and their various applications/weaknesses.  A question
came up about them and I advised staying away from type
K (chromel-alumel) as they were at their limit in that
app and not suited for the hostile environment.  I was
asked what I recommended (they got me there ;-)  so I
deferred to you.  From what you're telling me, I deduce
that they use K-type in a SS sheath (probe).  You have
confirmed my warning with your statement about the life
span of these type probes.  I had wondered if there were
any made with a longer life -- guess not.

>> Anyways ..... I wanna know what you can tell me (us)
>> about EGT sensors.  What are they made of (type TC, what
>> are they encased in, etc), where does one get them, is there
>> any readily available, reasonably priced (stupid question)
>> instruments to read them?  What can be reasonably deduced
>> from them?
>
>EGT probes are common as dirt in aircraft circles.  There are at
>least two different companies that make them.

        [ snip ]

>The folklore, on aircraft, is that absolute temperature measurements are
>not important.  What's important is the point at which the temperature,
>reported by the EGT as voltage, PEAKS.  That's the point at which the
>mixture is at stochiometric.  We use multiple EGT probes in aircraft because
>it's common for the cylinders to each peak at different mixture settings
>(due to mixture maldistribution in the intake manifolds).  What we're
>interested in there is the EGT DISTRIBUTION between cylinders.

the problem I see with EGT in an automotive app is we typically
don't have the ability to dynamically adjust/control the mixture,
and we're not operating at constant rpm/load as in a plane.

Thanks again,

Tom Cloud <cloud at peaches.ph.utexas.edu>