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From: "Bill Bradburry" <bbradburry@bellsouth.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
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Subject: RE: [FlyRotary] Re: 295cc vs 495 cc Renesis Test[FlyRotary]
Date: Wed, 24 Jun 2009 02:41:47 -0400
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Dennis,
Thanks for helping to further this along.  What you discovered is something
we all need to know and before we are in trouble when we find it out.
I think George is correct about the color/sizes.
One thing I am curious about is the fuel flow you would be showing when you
do these tests.  Do you have the EM-2?  I think you do if you are reading
HP.  If we know what the injectors should produce and compare it against the
GPM that the EM-2 is reporting, it would be kind of a back door way to
calibrate the EM-2 and could put some light on what pressure the injectors
should be run at.
I checked a couple of things.  If the injectors produce the rated 295 output
at 57 psi, then you would only be getting a total of 507 CCM on primaries
only.  If you were truly developing 140HP with a BSFC of .55 (how accurate
is that??) it would require an output of 808 CCM of fuel.  I think probably
you were not getting that much HP.
What manifold pressure and rpm did you have when you started to see the
leaning occur?
I wonder what would happen if you turned the primaries off and ran on the
secondaries only.  Would they support full power?  What MP and rpm is full
power?
Looking at the secondaries. If they produce 495 at 57 psi, then you would
get a total of 850 CCM out of them at 42 psi and 100% duty cycle and that
should get you 148 HP

Bill B


-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of George Lendich
Sent: Wednesday, June 24, 2009 1:39 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: 295cc vs 495 cc Renesis Test[FlyRotary]


Dennis,
I thought the 495cc injectors were Blue and the yellow were 380 cc?
If your running your experiment with the Yellow injectors can you give us
some feed-back when your done.
George ( down under)

> I've been following the injector thread for a few days so today I 
> tried an experiment.  I ran my Renisis with stock injectors (295 Pri 
> and 495 Sec) on the ground to see how it ran with primary or secondary 
> injectors turned off and how much HP I could generate with the 295 cc 
> primaries.  Note - My fuel pressure is set at 42 psi.
>
> I found I could run around 140 HP ( HP as shown on the Not Calibrated
> EM-2) with the primaries on and the secondaries off.  I also found 
> that as I opened the throttle above the 100 % duty cycle of the 
> primaries the engine would go lean quite rapidly and quit. If I were 
> in take-off mode at low altitude and had a secondary injector fail I 
> don't believe I could diagnose the problem easily  and keep the engine 
> running on the primaries!!
> My theory as to why the engien quits is that as I am running only on 
> the primaries and I advance the throttle beyond the point where the 
> primaries are at 100% duty cycle the engine starts to go too lean and 
> the RPM's decrease - This causes the MP to increase because the engine 
> is pumping less air.  As the MP increases the volumn of air in the 
> combustion chamber increases.  You need more fuel to compensate but 
> the injector is already supplying the maximum fuel it is capable of 
> supplying.  The fire goes out and the engine quits.
> I believe to keep the engine running when I have a secondary injector 
> fail I'd need to throttle back to some where around 18 inches MP 
> before turning off the secondaries and figuring out the secondaries 
> are bad.  If the engine ran smooth on the primaries I could slowly 
> advance the throttle to increase HP as long as I did not go too high 
> MP and get into the lean condition.  This is just too much stuff to do 
> at low level just after take-off!!
>
> I now plan on replacing the blue 295 CC primary injectors with yellow  
> 495 CC secondary injectors!!
>
> Dennis H.
>
>>
>
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