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Should be an interesting experiment Paul, can't wait to hear
results.
I tried a very short and now a medium-short manifold and find that it
works well IF it is very "clean" (proper diameter runners, no change in cross
sectional area, well matched to ports, etc, etc) The very short runners
gave up some power at climb rpm (FP prop) but did OK at cruise & top
end. The Medium-short version works about as well as my long (so-so clean)
manifold (~17" runners) and real good at top end.
FWIW, my guess about your dripping throttle body is condensation on the
runners & throttle body walls. Gravity does the rest. Agravating
the problem is the "cool side injectors". Someone called this arrangement
the "Holy Grail" of intake design. I'd call it the "Sacred
Cow".
Tracy ( eat sacred cow for lunch).
----- Original Message -----
Subject: [FlyRotary] Re: Short intake
manifolds
Hi, Tom....I saved a few posts that addressed the problem you
were referring
to. The folks at Mistral also went into a lot of detail
about it. Problem
is, they were talking about the LONG intake runners, and
having the
injectors at the far end, away from the engine. Power pulses
problems,
incorrect fuel mixtures, etc.
I am
not going to try the short manifold, (since I received one with
the
bolt-on fuel/ignition package that I purchased from Atkins Rotary), and
see how it works. I understand Dave Atkins has been using his for quite
some
time, with a lot of cross-country trips under his
belt.
Also, hearing Al's comments helps as well.
What the heck....I built an
experimental, so I guess it's expected I have
the need to experiment a
little. Thanks for the input, Tom. Paul
Conner
----- Original Message -----
From: "Tom" <tomtugan@yahoo.com>
To: "Rotary
motors in aircraft" <flyrotary@lancaironline.net>
Sent:
Tuesday, December 14, 2004 11:36 PM
Subject: [FlyRotary] Re: Short intake
manifolds
> Paul,
> There was a discussion here a few
weeks ago regarding 'back pulses' in the
> intake manifold. Sorry,
that may not be the correct term. IIRC, seems a
> short
manifold may have issues, one being fuel droplets being expelled
> the
> opposite direction. Let me suggest the
potential for it to pool in your
> 'outer chamber' and another potential
for a backfire to ignite it.
> Hopefully
> that is blatantly
wrong so those who know will step in and straighten it
> out.
>
You can tell by my terminology that I don't talk motors much. Also,
seems
> I
> read many years ago that the one reason aircraft
carburetors are hung
> below the
> motor is so any fuel remnants
would fall out and evaporate and not pool,
> lessening chances that a
backfire would have something to ignite. This,
> just
>
idle chat.
>
> Tom
>
>
> --- Paul <sqpilot@bellsouth.net>
wrote:
>> My question is....With the
>> short manifold
putting the TWM throttlebody over the top of the exhaust,
>>
has
>> Dave had any problems with fuel dripping out of the
throttlebody after
>> engine shutdown? Also, did he put any
kind of heat barrier between the
>> exhaust manifold and the
throttlebody?
>
>
>
>
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