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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: 295cc vs 495 cc was [FlyRotary] responses to responses, not developing full power
Date: Fri, 19 Jun 2009 07:28:35 -0400
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Message-Id: <20090619112835456.EJUY19511@cdptpa-omta03.mail.rr.com>

Don, if you are using stock Renesis (295 cc primary/495 cc secondary), then
I am not surprised you find the running rough when switching to just the
secondary.  Here is why.

Once you tune the EC2 to idle/low rpm - you are doing it before the EC2
stages, therefore the Ec2 is opening only the 295cc primary injectors and
you have tuned your engine (presumably) to run well at idle on the primary
injectors.  When you switch the primary injectors off and secondary
injectors on - the EC2 is still providing the same pulse duration (assuming
engine manifold pressure, etc are the same) for the almost twice as large
secondary injectors as it did for the smaller primary injectors. Ergo, you
are feeding the engine almost twice the fuel (for the same engine
conditions) as you did when on the primary injectors.  The engine is choking
on too much fuel.  

Those of use with the older 13Bs which basically had the same size injectors
in primary and secondary roles OR those using the Renesis who have replaced
the smaller 295 cc with the larger size secondary (which once again means
having same size injectors in both positions) can switch from primary to
secondary as the pulse duration is injecting essentially the same amount of
fuel regardless of which pair you have turned on.  

Since Many of us have found that the 13B will produce almost full power on a
single pair of 460/550 cc/min injectors - I personally favor replacing the
smaller 295 cc/min injectors with larger injectors.  Although two 295 cc/min
injectors will probably keep you airborne - its nice to have the option of
running on either pair.  But, as I said that is just my personal preference.

It sounds to me like the rough running on only secondary, the varying EGT,
etc, smacks of too much fuel for the operating conditions.  Try leaning it
more - you can't hurt the engine.

Let us know how it goes

Ed


Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.rotaryaviation.com/Rotorhead%20Truth.htm

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Don Wallker
Sent: Thursday, June 18, 2009 10:07 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] responses to responses, not developing full power


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