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RE: Back to EGT's

To: "Deikis, John G" <John.Deikis@va.gov>, <spridgets@autox.team.net>
Subject: RE: Back to EGT's
From: "Dave G." <dmg@bossig.com>
Date: Wed, 09 May 2007 09:23:02 -0700
John,

I assume that the EGT probes are in the exhaust manifold... i.e. 
downstream of the combustion chamber.
And you say you are measuring 1400 (F?) on hard running.
So the burning gas temperatures in the combustion chamber must be 
somewhat higher than that.
But, the  accepted melting point of Aluminium is a fraction above 
1220F.!!!   
I don't know how much cooling you would get from the incoming cold 
air/fuel mixture... but I would suggest that you might need to run a 
but richer or less advance....

When I used to 'drive' piston engine aircraft, I was taught to lean out 
the mixture till the EGT temp peaked and then back it off a bit. But 
that gives maximum economy... So, to get Max power, it must be backed 
off a lot more.  

Dave G.

> I'm SURE I caused the problem, the question is how.  I was kidding
> about
> the gauge "causing" hot running.  The thermocouples are very small--
> like a baby's butt thermometer.  Unlikely to cause restriction. 
> They
> are used by many 1275 racers.




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