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Date: Wed, 30 May 2012 09:56:11 -0500
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Subject: Re: [FlyRotary] Re: Injector balancing
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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I don't know if it does.  I've never tried idling on the secondaries
with this intake.  My previous intake used 60# Deka IV injectors for
primary and secondary injectors and it didn't idle well at all... 1800
rpm was about as low as I could get it to run smoothly.  But I
attribute that to the location of the primary injectors (upstream of
the slide throttle) which caused fuel puddling at low throttle
settings.  Since my secondaries are still located upstream of the
butterflies, I would guess it wouldn't idle very well either.  As I
said before, one of my goals for my new intake was to re-position the
primary injectors downstream of the butterflies in hopes of improving
the idle characteristics.  It appears that I accomplished that goal.

Mark

On 5/30/12, Bill Schertz <wschertz@comcast.net> wrote:
> How does it idle on secondaries?
>
> Bill Schertz
> KIS Cruiser #4045
> N343BS
> Phase one testing Completed
>
> From: Mark Steitle
> Sent: Tuesday, May 29, 2012 5:54 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: Injector balancing
>
> Ernest,
>
> With my current setup, this p-port engine idles better than my side-port
> motor ever did.  It will idle down to 750-800 rpm if asked, although I
> normally idle at 1500-1600.  Still, it might be an interesting experiment to
> add temporary dividers in the airbox to see what effect it would have on
> tuning.
>
> If you take a close look at the picture I posted you can see the blue fuel
> rail.  This is the primary fuel rail feeding the primary injectors.  They're
> located downstream of the butterflies, very close to the intake ports and
> pointed directly at the rotor faces.  I can't imagine how the fuel could
> find its way 18" back down the runner and back into the other runners.  I've
> never found any residual fuel in the airbox either.  I don't see how the
> fuel could be pooling so close to the ports, especially at 4500 rpm.  But
> then I'm not an expert in fuel injection design either.
>
> Alleviating fuel pooling in the runners was one of the design goals with
> this latest intake.  My previous slide throttle had both the primary and
> secondary injectors located upstream of the slide.  This caused fuel
> pooling, especially at very low throttle settings.  Needless to say, this
> made low throttle tuning almost impossible.  So, the new intake has the
> primary injectors downstream of the butterflies, and it idles great.
>
> Mark
>
>
>
>
> On Tue, May 29, 2012 at 4:32 PM, Ernest Christley <echristley@att.net>
> wrote:
>
>   Mark Steitle wrote:
>   > Ernest,
>   >
>   > I don't understand how that could happen if my injectors are after the
>   > airbox (see attached pic).
>   >
>   > Mark
>
>
>   At idle, the intakes coming off the airbox can set up some serious
> standing waves that will suspend fuel droplets and
>   let it stick to the walls.  You're set-up is very similar to mine, in that
> the fuel can run downhill and air has to pass
>   in front of one runner before reaching the others.  Some of that suspended
> fuel will coalesce on the wall and drivel
>   down the runner, and any coming out of the middle will get pushed back to
> the rear (which will then be running over rich).
>
>   It would also be interesting to watch individual MAPs across the runners.
> Dollars to donuts that the first runner's
>   inlet is at a partial vacuum compared to the rear one.
>
>   I may be wrong about the mechanism, but I know my fix fixed whatever was
> wrong.  I inserted a plate so that the runners
>   could not "see" the air intake.  The air hits the plate and spreads out
> before heading to the runners directly, instead
>   of flying past the first on the way to the second.
>
>   Going off of what I think I know, I would use a handsaw to cut a slot
> halfway through the plenum between the runners.
>   Then I would slide a partition between them.  It would essentially create
> three stalls that the runners originate from.
>   The point being that air would not be able to go past one runner on the
> way to the second.
>
>
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