Ken Powell wrote:

     Question for Ed Anderson:
     Ed,
     What length did you make your intake runners?  Somewhere between 18"
     and 24"?
     Does anyone know the length of Tracy's?  His seems to work really
     well.
     I understand that you have to decide if you want to tune for Power or
     efficiency (the rotary seems to have a 'sweet spot' for BSFC at about
     5000 rpm).

     Thanks,
     Kern Powell

Ed Anderson wrote:

Ken, I calculated the runner lenght based on rpm/speed of sound to get the total
distance port to port distance.  The column "1/2 of total distance ports" is the
results of that calculation.  The length contributed by the lower stock, the amount
of the upper stock manifold (most was sawed off) and the distance in the dynamic
chamber for the fiberglass paths.  Subtracting that contributed by those from the
figure in the 1/2 of total column gives you the required runner length. So my
runner is adjustable from approx 10" to 7" with tubes inside tubes.  The figures
you may see for runner lenght may vary as it is somewhat dependent on the port
configuration (degree open) when the pressure wave arrives.

E shaft     1/2 of total Lower Upper                         Runner           Total
RPM       distance    Stock   Stock  Fiberglass             Tube
               ports

5000            23.76    6.5       2.5       3.00               11.76        23.76

5500            21.60    6.5       2.5       3.00                 9.60        21.60

6000            19.80    6.5      2.5       3.00                 7.80        19.80

6500            18.28    6.5      2.5       3.00                 6.28        18.28


Needless to say the amount of lenght contributed by the stock lower manifold or
what ever you are using is part of the pressure wave path and must be taking into
consideration.  All dimensions are in inches.


Ed

 
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