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
Once the runner halves are cut apart, I think I can add material
to
the inside by welding in aluminum that could be blended, faired and
polished to make a smooth path for the air.
I plan to supply both oil coolers, intake air, cool tube and
radiator
from the belly scoop and the two cheeks. There will be no more
holes
in the cowl. I am willing to modify the cheek openings if I have
to
(or it might be possible to syphon air off the rad plenum for the
intake. Come to think of it, that is what I should do. Remember,
my
rad is only 13 inches wide. I can easily make a larger scoop and
section part of it off for the intake. Now we are talking.
Also, I am not willing to give up the air filter. Just think
what
one grain of blowing sand could do to your engine. The air filter
is
far more important than ram air to me. I like PowerSport's air
cleaner arrangement. They seem to be developing plenty of hp
without
ram air.
Are ram air and an air filter mutually exclusive? If I bring
air
in
through the belly scoop and just dump it inside the cowl,
creating
higher pressure inside the cowl, would not the engine easily be
able
to draw all it wants?
Here is a drawing of the round plenum with a flat for injector
mounting. Jerry
How dusty is the strip you fly off? Tracy has been flying 1400 hours
off
his dirt strip with no filter.
We don't have any performance data on the Power Sport airplanes.
If they had any balls they would enter the Sun 100 :)
Heck if they entered and they beat Tracy and they went
over 220 MPH they would win the $750 Everett Hatch Memorial Fund
prize
money.
Here is another couple with the snorkel.
It would look better without the cheek inlets but then you would
have
to sell those oil coolers :)
Paul Lamar
One thing the snorkel has going for it is the simplicity. That is
appealing. And on top of the cowl it should see clean air. But I
have been on one dirt strip or another since I started flying. Some
of
them, especially in Calif, were extremely dusty. If you find
yourself
it that situation, then what? Screw the engine? I don't think that
is practical at all. Maybe one could rig it so that if needed, air
could be switched to a filtered source similar to the way carb heat
operates. Jerry.
Just stuff a K&N cone filter in the 3 inch opening and duct tape it
in
place. You'll lose a bunch of power but you can still fly.
Air pressure will help hold it in.
That last idea is what Mooney does. Put a slide valve in the ram air
scoop
and a tennis ball one way valve in a filtered hot air pipe feeding one
end
of the plenum. Once the ram air valve is open the tennis ball one way
valve will close.
Paul Lamar
Will you draw such a system? Please. Jerry
Here is a slightly better version.
BTW if the snorkel ices up this ball valve automatically opens up
providing heated air to the intake system.
Paul Lamar
There's a risk of RPM and relative manifold/ambient/ram air pressures
combining to rattle that ball back and forth.....just so long as you
avoid that setting.
Chris Cosman
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