> >Jerry Hey wrote:

 >>
 >>  Does the rotary perform best with zero exhaust back pressure?

I am

 >>  designing my new system  and want to go for max power.  I

have a zero

 >>  back pressure design that will also be quiet.   (Did that

get your

 >>  attention?) But if a little restriction will help that can be

done

 >>  as well.    If so,  how much?    Thanks,    Jerry

 >Due to an exhaust/intake  overlap it is not that simple. All I

know

 >is about 32 inch exhaust pipes with 22 inch intake for 6000 RPM
 >seems to be the hot tip with no back pressure.
 >
 >Paul Lamar

 Is that 32 inches of 2" pipe before the muffler?   How was this
 number derived?  Is there a resource I can read? The Star Mazdas

have

 a muffler which surprised me when I saw it.   I can't believe it

is

 about noise when it comes to race cars.  Lynn?           Jerry

Yes.

Well two sources. The Mazda tech papers which are on:

http://www.thecarricos.com/ACRE

in PDF format and the work that Everett Hatch did.

Here is just one graph from those tech papers.

O.K.  32 inches  of 2" pipe.  Surely this is  affected by the
muffler.   But how?  Can the muffler be part of the 32 inches?  Does
the turbulence created by the tangential muffler increase back
pressure, or does the increased volume of the same muffler, lower
back pressure?  Maybe they roughly cancell out.

   Putting a 3 inch outlet on a six inch dia muffler probably has a
negative effect.  The exhaust gas has to recompress to pass through
the 3 inch outlet.  Following this "logic,"  the muffler might be
equally efficient if it was just a 3 inch dia pipe.  At one end the
exhaust pipes are joined tangentially. The other end is the wide
open termination of the exhaust system.

  So easy to speculate when you don't know anything.    Jerry

p.s.  I could not open the carricos  site , although I have been
able to do so in the past.  It timed out after a minute --several
attempts. Will DSL  ever make it to the boon docks?

[Todd Carrico]
Sorry about that, power went out for 6 hours or so.  My UPS's only
lasted about 20 minutes :(.  Course lost a refrigerator of food, and the
opportunity to spread the knowledge!!  Please try again...

tc  http://www.thecarricos.com/ACRE/

 
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