EGT for feedback

[Garfield]

On Thu, 1 Aug 1996 08:16:04 -0400 (EDT), Michael T. Kasimirsky wrote:

<snip>
>All the 
>recent talk of O2 sensors has got me wondering about another source of 
>combustion feedback.  Has anyone tried using exhaust gas temperature for 
>fine-tuning the intake mixture?  It would seem to me that you could lean 
>the mixture to increase EGT or richen to lower EGT.

I suppose many in this list know that this is exactly what is done on
aviation engines, manually. With just a tach, the mixture is leaned to max
RPM and then richened back 50 rpm, say. With an EGT, a thermocouple is stuck
in the gas flow through a hole drilled in the exhaust stack of what is
expected to be the hottest running jug just after the header, and again
mixture is leaned to peak EGT and then enriched to 50-100deg drop, say,
(much dependent on the engine). This manual procedure is still about the
only option even in modern times, because the O2 sensors really get messed
up by the ton of lead that is still in 100LL aviation fuel, the most common
fuel used in 95% of all GA aircraft.

Garfield