Al, I don't know much about
induction systems and they appear to be as much "Magic" as science.
Obviously, I don’t either. But I’d
like to be able to get it out of the realm of magic.
However, there is little
question that Tracy's engine puts out closer to 180
HP than 165. While its not been on a dyno, he has flow with 180HP O360
RVs and bested them. In fact, during the Sun & Fun 100 airrace, he
not only beat all 0320 (supposedly 165HP) entries in his class but also
half of the entries in the 180HP class.
Tracy’s plane performs very well, no doubt about it. This
comparison just doesn’t tell you why.
Also, fuel flow is a fair
indicator of HP being produce and he and I have both seen 19-20 gph fuel flow
(on cold dense air mornings..
<snip>
that clearly gives you a strong
indication that he is producing at least 180 HP.
I agree.
My own personal story is
that when I had a Weber throttle body with two 2" dia throats with a
relative short length induction (about 1/2 my current length), my static rpm
was 5000 rpm, my top speed was 182 MPH TAS and rate of climb was around 900
fpm. When I created an intake using smaller (1 5/8 and 1 3/8" dia
tubes) of the length that theoretically are tuned to provide the "dynamic
charging effect" at 5900 rpm, my static went up to 5300 rpm, my ROC went
up to 1200 fpm and my top speed to 196 MPH TAS. So while I can't
prove that my current induction system is better "tuned" to my
operating regime and rpm - I sure like the improved results much better.
Given that speed goes by the cube root
of HP; the speed change suggests that your power increased by 25%; so maybe
something suspect there, or there was something really wrong with your original
setup. What else changed besides your runner length?
Too bad we don't have a
wealthy member of the list who would fund a little R&D with dyno time and
different induction system approaches on the rotary engines. But, as you
know that takes time and money and both are limited for most - if not all
of us.
Indeed!
Ed Anderson