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Thanks for the information, Tracy.....I think that by
going to the short manifold, I shouldn't have any more problem with residual
fuel in the intakes slowly running downhill and finding it's way out of the
throttlebody. I am glad to hear that shorter intake runners do, in fact
work, especially in cruise rpm, which is where I spend 90 percent of my time
while flying. I just want a simple setup, and I'm hoping this might be one
answer. Paul, getting rid of the sacred cow, Conner
----- Original Message -----
Sent: Wednesday, December 15, 2004 10:31
AM
Subject: [FlyRotary] Re: Short intake
manifolds
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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