Paul Yaw wrote:

Paul wrote:

Archie Frangoudis wrote:

Thank you for that encouragement Paul Yaw,
While many are working on induction systems,
when my new shop is built, I'd like to work on
a nice, efficient exhaust system utilizing racing
technology, or am I too late?
Archie

You are certainly not too late.  The CORRECT system for a rotary is a
long primary system 90+".  Since these systems do not fit airplanes or
most race cars, you are stuck with a short primary system.  The short
systems do not utilize the first reflection, and so you will be working
with a weaker low pressure pulse since it will have travelled back and
forth several times.  For this reason, the "thru flow" of the engine
during the overlap period must be greater to achieve complete scavenging
of the clearance volume.  The short systems are also more sensitive to
pipe diameters, and primary lengths.  Since you will be dealing with a
system that is not necessarily correct, (At least in terms of two stroke
theory) there is more to be gained by fiddling with primary lengths and
diameters, and secondary length and diameters.  Since you are not
worried about anti reversion (who cares about the powerband) a venturi
style collector will probably work best.  Once you find the "perfect"
system, it will only be truly optimized for that engine.  A change in
exhaust port flow, or timing will send you right back to the drawing
board.  If you are not using a peripheral port engine, all of this is
MUCH less crucial.  Just keep in mind that as compared to a piston
engine, the exhaust open duration will be approximately 50% greater, and
peak header pressure (Which initiates the return pulse) during the
exhaust cycle will occur much earlier beacause the port opens so
rapidly.  Bolting a rotary to your dyno will probably get you much
further, much quicker, than asking for someones elses recommendation.
Sorry this was so long winded.

Paul Yaw

 
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