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Date: Wed, 23 Jan 2013 08:27:55 -0500
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From: Paul Miller <pjdmiller@gmail.com>
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Subject: Plenum only to Cylinder heads
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Thinking about all the air leaks that typically show up in the IO550 =
Legacy cowl. A full size plenum has been accomplished by some folks.  =
What about a plenum that went from the inlet and simply exited onto the =
three cylinder heads on that side?  It would be smaller, maybe easier to =
build, lighter.   You could use a silicone seal where it would fit on =
the barrel to keep a tight fit and wires could be kept away I believe.

How much better would the cooling be and would the lack of air to the =
rest of the crankcase or cylinder bases cause problems?   Still need to =
route some bleed to the accessories and oil cooler which we do already =
but I'm talking about ducting the inlet straight to the head and =
avoiding most of the leakage points and perhaps achieving better overall =
cooling.

Second:  Why does the alternator duct exit below the engine?  The exit =
air may be warm but certainly less than CHT so why not duct the =
alternator exit back into the upper deck and regain the pressure loss =
that goes straight through the alternator and bypasses the cylinder =
fins?

Thoughts?

Paul
Legacy=