Further to my recent response to
Tracy’s
posting, I wanted to clarify that I was not disagreeing that there benefits to
be gained from tuned induction. Clearly there are.
SNIP
So, I don’t
know. We need some data. Tracy is
guessing that his engine puts out 180hp. Could be; but I’m guessing we don’t
know what it is, and it could just as likely be 165.
Al
Al, I don't know much about
induction systems and they appear to be as much "Magic" as science.
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. 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). But utimately, I think its the
performance of his RV-4 which is not a particularly aerodynamically clean
airframe (compared to some), with a top speed of over 214 MPH and his average
of 209 MPH over the Sun & Fun race 100 mile course from a
standing start with a fixed pitch prop (and a draggy muffler hanging in the
slip stream) that clearly gives you a strong indication that he is
producing at least 180 HP.
Not Proof?, nope, don't claim it
is, but the preponderance of data strongly indicates Tracy's engine is
producing at least 180HP. 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.
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.
Ed
Anderson