I don't know enough about the wavelength of the pulses in the intake

system,

     > but could it be possible that the folks using smaller pipes are

getting more

     > benefit from the tuning effects than someone that selects intake

plumbing

     > too large?  I don't know that I've seen the frequencies discussed

here.

     >
     > Andy Hecker

Andy, What is happening with small diameter pipes is you are tuning for
the least restriction, (with respect to a given wavefront), at a given

RPM.

There is always reduction in mass flow until the pipe becomes more than
big enough to fill the chamber at 100% efficency. Then tuning can allow
more than 100% as is seen with the computed numbers for rotarys in many
cases. I understand Paul's frustration with explaining this as pipes that
are too small are of little use to us. To someone with a desire to spend
a lot of time just above idle, ( a motorglider perhaps?), there may be

some

benefit. For an engine that will spend almost it's entire lifetime at more
than 50% power there is no reason to not use the largest workable pipe.
The thing to rember here is the LeMans engine was built for an era where
there was an efficiency formula. You only got a certain amount of fuel for
the entire 24 hours. If you ran out you were screwed. The reason for the
third plug in the LeMans engine is to get a 1-2% improvement if

efficiency.

There was little detectable power gain. Run the 2" pipes if they will fit!
I will probably run 3 large diameter pipes on my 20B even if I run a 2

port

manifold for side ports.
Bill Jepson

 Hi Bill,
 Thanks very much.  I'm not advocating smaller pipes, and certainly don't
want to add to Paul's frustration levels.  Vance's comments, and the Taylor
article's mention of standing waves, dug up an old (and probably irrelevant)
memory about wavelength vs. pipe diameter.  I could assume that the
wavelength is larger than 2 inches and thus all of the probable pipe sizes
are acting as point sources.  I could also assume that the wavelength just
doesn't matter. (grin).

Happy New Year All,
Andy

 
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