Ed Anderson wrote:

Ok folks,

    Fired up the engine with the new intake with the polyurethane resin
casting plenum/throttle body - Fuel injector mount using Paul's manifold
casting.  The good news is that while I don't appeared to have picked up any
performance at static (didn't really expect to as I put on shorter and
bigger tubes which should have raised the rpm for best torque over the old
system), but on the other hand the plastic plenum didn't blow up either
{:>).

    Static on runup was 5400 rpm with air temp at 80F and 100% humidity.
Idle would not come down below 2200 rpm indicating an air leak.  OR the
3/16" dia hole in the throttle plate needs plugging.  I stuck my thumb over
it and the rpm did drop, couldn't tell how much as could not watch the tach
while doing that, but it sounded like a couple hundred rpm.  I'll use some
JB weld to plug the hole and then see.

   Here are a couple of photos.  One of my objectives was to reduce weight
and  I have shaved off 12 lbs off the old intake with the new one weight 11
lbs with manifold casting, tubes, plenum, throttle body, fuel injectors and
fuel rail.  .  Another objective was to clean up the exhaust side of the
block for later putting a turbocharger there.  As the second photo shows,
plenty of room for the turbo now, note how snuggly Paul's casting bolts up..
Note the oil on bottom of flange from cutting and refitting oil pressure
sensor line.

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com

BTW folks I want to clarify something here just so no erroneous conclusions
are drawn. Strictly speaking Ed is using a dynamic chamber and not a simple plenum.
I am sure Ed did not intend to mislead people.

Here are some pictures Ed sent earlier. I want to go on record as not recommending
this design. Dynamic chambers with this length of intake runners are
designed to enhance the torque at 2500 to 3000 RPM. High torque at that RPM  is 
not needed in an aircraft engine. IMHO this design hurts the ability of the engine
to generate power in the 5000 to 7000 RPM range.

My recommendation is to use a simple plenum or helmholzt resonator
chamber of twice or more of the engine displacement. For the 13B that would
be 160 cubic inches or 4 X 4 X 10 inches or 3 X 3 X 17 or 3.5 X 3.5 X 13 inches
with a throttle body with a straight shot in from one end.

In Ed's design the air is forced to make a two sharp 90 degree
turns instead of only one.

Paul Lamar
 
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