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> My 320 is a couple months from flying and I am in the process of finishing
the
> top of the cowl. The cooling arrangement I have chosen for my stock
IO-320-
> D1B (160hp) is as follows:
> o Standard factory baffling
> o Large NACA duct on the right side of cowl for oil cooler
> o "Shark gill" exit for oil cooler air on left side of cowl
> o No "ramps" inside cooling air inlets
> o Blast tubes for mags and fuel pump, taking air from rear baffle
>
Hello Dan,
Here are some observations from 450 hours on our 320.
1. Standard factory baffling, well sealed. Our CHT's still run a little
warm.
2. Large (2 x the cabin NACA in the manual) NACA duct on the left side
of cowl for oil cooler. My oil temps ALWAYS run too cool. Behind the NACA
duct I built a gradually expanding plenum that is sealed to the cooler.
Every molecule that goes into the duct comes out the back side of the
cooler.
3. Shark gill exit on the right side bottom NOT connected to the oil
cooler. We installed this in an attempt to get more flow through the engine.
This installation cooled the CHT's about 10 degrees.
4. We added ramps inside the cooling air inlets. These cooled the CHT's
about 10 degrees.
5. No blast tubes.
6. We are in the process of adding little "lips", kinda like mini cowl
flaps to the bottom of the cowl exit in an attempt to bring the CHT's down
another 10 degrees or so.
I believe that if you put in an efficient duct / plenum for the oil, you
won't need a dedicated exit. I need to put in a butterfly valve to get my
oil temps UP. I haven't heard of any LNC2's running too cool in the CHT's.
Let the shark gill exit draw more air through the engine rather than the oil
cooler (assuming your oil temp is acceptable).
I believe that the ramps should probably be installed. They can't hurt and
it's such a simple, easy installation. I just microed some big foam blocks
to the upper cowling, shapped them with sandpaper and put a 2 bid over the
whole thing. If I were starting from scratch, I'd probably go the engine
plenum route like Mark Ravinski, Scott Krueger and others.
This is mine, your's will surely be different. Hope that this helps. Let me
know if you need any more info.
Bill
harrelson@erols.com
N5ZQ LNC2 O-320 VA42 Fredericksburg, VA
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