Jerry Hey wrote:

Paul,   I cut one inch out of the center of the 180 degree bend.  The
result is a less than perfect radius but not  bad.   The runner now has
one half inch clearance over the engine.  And,  the option to lean  the
runners toward the firewall still exists.     This move also gets me
back to a 12 inch spinner and the stock Tailwind cowl.     A four inch
dia round plenum might work better.       Jerry

p.s.  I recently got a scroll saw.  It is very useful for this kind of
stuff.   I don't know how I ever got along with out one.

I would not do that Jerry. The air will see that discontinuity and bounce.

Better to put a little hump on the cowling. AKA Power Bulge in the automotive
world:)  Glue on some foam to the top of the stock cowling shape
it with a long rasp. Sand and lay-up a little gup on top. Finish off.
and then rout it out from underneath. 

Come to think of it that might
be easier to do if you just went to a 16 inch spinner and then just filled
in around the spinner on the stock cowl. Both top and and bottom.
Looks like it might cut the drag a bit. The cheek inlets
would get smaller but they are probably too big for the oil coolers as they
are. You will have to build a scoop near the lower front anyway for the
rad. Looks like it is time to do another cowl. 

I'll see if I can come up
with something better and still keep the cheek inlets for your oil coolers.

The four inch round makes it hard to seat the injectors.

Paul Lamar
 
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