Message-Id: <3.0.3.32.20000314124622.00b79370@olsusa.com>
Date: Tue, 14 Mar 2000 12:46:22 -0500
To: lancair.list@olsusa.com
From: John Poco <poco1@llnl.gov> (by way of Marvin Kaye <marvkaye@olsusa.com>)
Subject: Re: Oil Cooler
Mime-Version: 1.0

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In regards to Dan's question of oil cooling here is what I did.  I was
fortunate to see Mike DeHate experiment with oil cooling in his 290/235
(lycoming 290 in a 235).  Mike had a hangar just down the row from me.
Mike tried a lot of things including tufting the outside of the cowl etc.
I'm not sure if he ever solved his problem.  Out here on the west coast it
is not uncommon to see 100F or higher temperatures in the summertime.  I
was determined to not have an oil temp problem.  I made a NACA scoop on the
co-pilot side that fed air to the oil cooler mounted to the firewall on the
pilot's side through 3" scat tubing.  The NACA scoop could also have been
placed on the pilots side but I felt I had more room on the co-pilots side.
In fact Theo Mulder put his scoop on the pilot's side.  We were only a few
hangars apart!  I exited the air with a "shark" type of vent cut into the
cowl.  Again this was probably overkill.  Theo exited his air into the cowl.

The real question is how did it perform?  In extremely hot weather I NEVER
see high oil temperature even with somewhat prolonged ground use.  The one
bug that crept in I discovered the next winter.  I couldn't get the oil
temp high enough during those 10,000 ft climbs over the Sierras.  When the
temps got down into the 20's there was too much cooling.  My solution was
the installation of a butterfly valve just before the oil cooler.  This let
me shut off the flow to the cooler to regulate the temperature to what
ever I desired.  I used a simple cable in the cockpit, Theo tied his to a
Mac servo.  A more elegant solution is to have a door on the naca scoop.
With the lack of air molecules to cool your engine in Colorado I would
suggest a separate oil scoop and empty into the cowl area.  My 2 cents
worth.

John Poco
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