Jim, I went through the same problem with the IO-550D in my C-185. The
complimentary problem was that #6 ran cool all the time, and when pulling
power back to decend, was the one to set off the shock cooling alarm.

I know that there is little comparison between the cowl of a 185 and that of
a Lancair, but I'll offer this, at least it is cheap and easy.

I solved both problems with a baffle in front of #6. I made it removable,
and started out where it blocked most of the number 6 cylinder. This was too
much, and made #6 run warm. Amazingly (to me at the time), it seemed to
direct the airflow up and partially over #4, onto #2 which now ran much
cooler.

By trimming the height of the baffle 1/8" at a time, I finally arrived at a
compromise where #2, 4, and 6 ran fairly close together in temp, even in a
power-back decent.

Good luck

John Huft
RV spy



-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Jim
Cameron
Sent: Monday, April 06, 2009 5:41 AM
To: lml@lancaironline.net
Subject: [LML] Hot #2 on IO-550-N

    Friend of mine is scratching his head over his #2 cylinder on an
IO-550-N.  Runs about 40 degrees hotter than the rest, although all his
EGT's are nearly the same.  He spoke to a retired Continental engineer,
who told him that a lot of the IO-550's had that problem.  My friend has
checked all the obvious, baffling leaks, shrouds fitting properly, etc.  
He tried putting the oil cooler door on and closing it part way,
thinking maybe that would push more air over the cylinder.  No dice.  
The problem seems to be not enough air flowing down between #2 and #4 --
that's the exhaust side of #2.
    Has anyone else run into this?  Any ideas how to push more air
through there?

Jim Cameron
Legacy N132X
 

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