Exhaust temps...

[Charles]

Steve wrote:
>Omega supplies a lot of auto companies with thermocouples for exhaust
>gas measurement.  I'm curious, did they recommend the 1/16" 321
>stainless?  Are you running one in each header tube?
>
	No, just one, in the log manifold at the entrance to the turbo. I
wanted the fastest possible response time, so I ordered the smallest
diameter. They weren't sure what to use - the only application their
engineer had seen was on a diesel truck, which vibrates more but has a
much cooler exhaust.
	321 is what jet engine exhausts are made out of. If it won't hold
up, I'm not sure what material will! They had recommended 316, but
according to a metallurgy handbook, it did not have a high enough
melting point for a safe margin.
	If anyone can dig up the figures, would you please post them?

>Sounds like you need a better alloy with more nickel and vanadium?
	Like what? See above - I thought 321 was the "ultimate"
stainless.

>Wow.  For a naturally aspirated engine, I've seen temps at 500-600 F
>at idle.

	Must have had a very rich mixture and advanced timing? Mine is
deliberately retarded at idle so that it reduces the emissions.
	Anyone else have temp figures we can compare?

-Charles
'81 745i