>>      >
         >>      > 3) The VAM muffler *almost* fit.  The exhaust pipe hits
        one of
         >>     the mount
         >>      >
         >>      > tubes, preventing the exhaust manifold flange from
   seating
         >>     against the
         >>      >
         >>      > engine correctly.  There seem to be 3 possible
   solutions:
         >>      >
         >>      >    A) Make an insert for the manifold flange which
   adds appx
         >>     1/4".  Not
         >>      >
         >>      > convinced the bolts are long enough for this.
         >>      >
         >>      >    B) Cut the exhaust manifold pipes & lengthen them
   so the
         >> VAM
         >>     moves
         >>      >
         >>      > 1/4" - 3/8" farther away.
         >>      >
         >>      >    C) Cut the VAM exhaust tube & increase the angle
   toward
         >> aft so it
         >>      >
         >>      > clears tube.
         >>      >
         >>      >
         >>     Mark,   When I built the muffler, I did it with the engine
         >> mount in
         >>     place.  I had it off and on many times.  It had to be
   angled
         >> just so to
         >>     slip it over the flange studs, but it did fit. I have no
         >> ideal  why it
         >>     would not fit now.  Of your proposed solutions, the
   last one
         >> would be
         >>     easy to do. Cut through three sides of the exhaust so the
         >> last  side can
         >>     act as a hinge. (It can be cut on a band saw or with a
         >> plasma)  Heat
         >>     with a torch and pull it the position  you want.  I can
         >> send    you some
         >>     321 strips for the patch and also some 347 tig rod
   (required
         >> to  weld
         >>     321).   Or, you can patch it with 304, readily available
         >> everywhere.  To
         >>     weld 304 to 321, use 309 rod.
         >>
         >>       I am very disappointed that you are having difficulties,
         >>
         >>       Jerry
         >>
         >>
         >> We were able to get the muffler over the studs no
   problem.  The
         >> trouble
         >> was getting it to fit completely against the engine - in this
         >> case,  the
         >> bottom could not touch because the exhaust pipe was
   contacting the
         >> engine mount.  How thick is the gasket material which fits
   between
         >> the
         >> engine & the muffler flange, Jerry?  We were doing a dry-fit,
        but it
         >> didn't seem that close to fitting -- perhaps you had
   gasketing in
         >> there
         >> & it was enough?
         >>
         >> Agree that increasing the angle of the exhaust square-tube
   is the
         >> easiest way to adjust it.  Do you suppose there is any
   reason to
        make
         >> this adjustment way up by the VAM, or could it be done a
   couple of
         >> inches down (where it will be easier to do)?  The only
        difference is
         >> that doing it a couple of inches down would put a 'bend' in
   the
         >> pipe --
         >> can't see that a bend would make any difference.
         >>
         >> Mark & Mark
         >>
         >> It was kind of loud on the dyno so a bend might help.
         >> Also you might want to weld in a few of these while you are
         >> at it. They are reputed to reduce the noise.
         >>
         >> BTW Mark if you use the stock M2 cowl what are you going to
         >> do with the cheeks?
         >>
         >> Paul Lamar
         >>
         >
         > Mark,  I agree that the bend will be of no consequence.  As
   far as
         > the "silencers" I would wait until  you run it and make a
   real sound
         > check.   It would also be possible to "drop in"
   turbulators   into
         > the exhaust pipe portion.  If it is too loud put in one or
   two and
         > then test.  Keep adding them  until you get the sound you
        want.  This
         > is exactly what I intend to do, once the system is bolted to
   my test
         > engine.  The turbulators would be made from pieces of SS
   angle.  You
         > can put them in a grid to disrupt the exhaust gas flow as is
   done in
         > the Spin Tech.     Jerry
         >
         > Its pretty load Jerry as is. It does have a somewhat
   mellower sound
         > however.
         >
         > Paul Lamar

        Mark,  this is an opportunity if you are willing to do the work.
        Without changing anything, test the sound level of the
   engine.  Also,
        check peak static rpm.  If it is too loud, you can add the louvers
        and test both sound and performance again.  And so on.  We are so
        starved for real data on the exhaust.  Everything we think is
        speculation and quite possibly not worth a damn. If  you can,  get
        measurements of the exhaust  temp at the flange, inside the muffler
        and also air temps entering and exiting  the cool tube.   This data
        would be a major contribution.   I think Bob White is planning
   to do
        the same.    Jerry

        Don't forget guys this is not your average puppy rotary engine.
        It is a 250 HP P-port. I am the only one on here that has actually
        heard it run :)


   As it happens, I have a decibel meter which can meter both fast and
   slow
   response (A type and C type, as I recall) sound levels.  I will take
   measurements all along the way to first flight.  Better still -- there
   is a large open field near the hangar that I can taxi into.  I will
   take
   measurements out there so there is no echo mucking up the readings.  I
   will also take measurements every 90-degrees around the airplane at
   various useful distances, at various meaningful RPM levels.

   This of course presumes we actually get the thing installed, running,
   and are in a state to move out of the hangar w/o being a hazard to
   ourselves or others!

   Mark & Mark

   Speaking of being a hazard guys take it easy when you feed the power
   into this beast. Tracy nearly killed him self with only 200 HP on his
   first flight.

   I would wait for 100 MPH before I opened throttle all the way. Unless
   of course you are already up at 8000 feet out there in CO.


Field altitude is 6873, density altitude is typically 8000 - 9000 feet.
Now everyone knows why we wanted all that HP -- I'm tired of flying
things that stagger into the air.  Pulling back on the stick & going up
would be a novelty.

Mark & Mark


I see. :)

Paul Lamar