I got a chance to go up today and try out the axial flow muffler that
Paul designed. Well, top speed is up quite a bit, despite a really
draggy area that I have not faired in yet where the muffler exits the
fuselage. I'm sure I will get at least 10 more mph, probably 15 when
I fair this area in. At 3200 msl, and 27.3 inches of manifold
pressure, I was doing 150 mph at 6600 rpm with 170 f coolant temp and
190 oil, on a 60 oat day. Anyway, I'm fairly happy with that, it's a
good start and should improve with more streamlining work. I still
run an air filter, don't think I want to risk running without.

Brian Trubee



Brian,

What did you have before?  Do you attribute your higher speed to
more HP from a freer-flowing exhaust minus the increased drag
fron increased wetted area?  Thanks.

Gene Kahn

Hush Power.

Paul Lamar


I'd have to say it's an increase in HP due to decreased backpressure in the exhaust. The current configuration of the airframe is more draggy than the way it was with the old exhaust. This is something for me to address in the near future, but in the mean time the weather is finally nice up here so I have to go flying a bit also.

Brian Trubee


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