Mark,

The reason that I asked the question about idle on the secondary injectors is that when I first started the engine, with a Blue Mountain EFIS, I found that the engine ran very rich on the primaries, which were preferred by the EC-2 at idle, but when I switched to the secondary injectors the engine smoothed out. This led to the investigation of why, since all my injectors were the same size. I then found the problem with the BMA tach signal holding an injector open (or causing it to close slowly) that was fixed with Tracy’s recommendation of a 2K resistor in the line to limit the current draw from the BMA.  Just a diagnostic.

 

Bill Schertz
KIS Cruiser #4045
N343BS

77 hours

 

From: Mark Steitle

Sent: Thursday, May 31, 2012 6:23 AM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: Injector balancing

 

Tracy, 

 

Yes it is wired per your schematic with separate switches for primary and secondary injectors.  I just haven't tried to see if it will idle on the secondaries only,  and I don't really understand what this has to do with my current issue of cutting out at 4-5k rpm.  But I can run the test anyway.

 

Q:  When you bench test & update the s/w on EC-2's do you look at the fuel injector signals?  What would you suspect as to the cause of an extra rich mixture in one rotor? 

 

Mark

On Wed, May 30, 2012 at 9:19 PM, Tracy <rwstracy@gmail.com> wrote:

Mark,
If you have the injector backup mode switches installed, all you have to do is disable the primaries while idling and it should go to the secondaries automatically.   You may have to be ready on the mixture control to lean it out when you switch over  since your secondaries are larger.

Tracy

On Wed, May 30, 2012 at 10:56 AM, Mark Steitle <msteitle@gmail.com> wrote:

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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>

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