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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