Legacy and Super ES builders,

I'm not sure this wheel needs to be reinvented.  A tremendous amount of time
and effort was done to optimize a system for the Questair Venture a number
of years ago.  From the CAFÉ Foundations, The EPG and Aircraft Exhaust
Systems - III, Jim Griswold (Venture engineer) was quoted:

"The Continental IO-550G (Venture engine) was certified at 280 hp using 2500
rpm. The engine had tuned induction (top of engine) and neutral exhaust (8"
stubs out the bottom of the cylinder). The calibrated test engine delivered
284 hp and .375 bsfc. This same engine was fitted with the tuned/ muffled
exhaust and delivered 302 hp, .365 bsfc, and peaked all EGT's within 1% fuel
flow during a lean-out. The system routed the three cylinders on each side
to a common collector/muffler. The risers were 1.5"x.035"x34". The
collector/muffler was 2.25" x .035x30.4". This 64.5" system was optimum at
2500 rpm."

I think the IO-550N is essentially the same engine with 9:1 instead of 8.5:1
compression and rated at 310 hp at 2700 rpm.  I want mine optimized for 2500
rpm as well.  Am I missing something, or is the answer right there, as far
as pipe info, to make the optimum system for our engines.

John Chambers
Legacy 129
Still learning, still building.


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