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> Charlie,
> <... Or have I completely
missed the point & the goal is actually to tune for air
> temperature?
...>
> Actually, if I'm not badly mistaken, that's exactly what we're
tuning for. I
> haven't done any of the studying that Ed has,
.... But a lot of the talk here turns on
> "resonance" and "wave
pulses" and what not. Resonance is sound. The pulses
> we're
discussing are sound. Sound travels at the speed of sound.
. SNIP
. If we design for
> relatively mild
temperatures, say 60F, we can cruise comfortably at 8k' - 10k'
> during
the summer. Just climb until the intake charge matches the design
intake
> temperature and cruise there. In winter, we can
turbocharge, adjusting the
> wastegate to achieve the desired intake
temps. We might have to cruise at 15k'
> in winter, adjusting boost
to achieve the intake temps we need for resonance.
>
SNIP
. Runner length is not the only
variable. Perhaps
> there's some advantage to looking at them
all
>
> Or perhaps this whole thing is just a remarkably extended
brain fart... Jim S.
>
Hey, hey, Jim. Watch who's work you are
calling an "remarkably extended brain fart.."{:>)
Right, except with the EDDIE, resonance does
not enter the picture, if this definition of resonance is anywhere
close: Resonance [n] a vibration of large amplitude
produced by a relatively small vibration near the same frequency of vibration as
the natural frequency of the resonating system. Resonance is
a factor in most of the "tuning" theories such as the "Organ Pipe" and Helmholtz
Resonance theoreis, but not in the EDDIE.
However, the speed of sound is a factor as you indicate, which
is dependent on the ..Lets see if I got the lesson right ... dependent on the
TEMPERATURE of the air in the intake manifold --Yep! think I've got that
relationship down now.
Changes in manifold air temperature do
perturbate the EDDIE RPM point as you said. However, it turns out
there is another factor (in addition to RPM) that is much more
dominate (don't ask - won't reveal, confirm or deny until Shady Bend
{:>)) in determining EDDIE rpm than temperature. Don't
misunderstand, temp does play a non-minor role, for example a 50F drop in temp
would equate to roughly 2.5" (port-port) decrease in length needed in
your intake, IF you were going to hold the EDDIE rpm at its design
point. The reason, of course, is that since the speed of sound drops with
the decrease in temperature, to maintain the same timing you would need to
effectively shorten the manifold length to compensate - IF you were trying to
maintain the design EDDIE point.
There is always the possibility that there is a
major flaw in my analysis or synthesis of the governing equations - that I am
just oblivious to. To date, I've only showed it to one other person and
nothing obviously incorrect jumped out to them. However, I intend to have
Tracy Crook review it at SERFI next weekend, so if you never hear from me again
after that you can draw your own conclusions {:>)
I mean how much would you trust the work of a guy
that tried to throw "density" into the speed of sound equation?? Actually,
I used the correct formula for speed and temp, but thought that the
reason the speed changed with temp was because the density of air
changed with temp.
But, the EDDIE provides an
answer for every strange thing I've noticed about power production
with my installation - and besides it stacks up well, when compared to what
little concrete we think we know from Mazda about their use of the effect in the
rotary.
Ed Anderson
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