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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: 295cc vs 495 cc was [FlyRotary] responses to responses, not developing full power
Date: Fri, 19 Jun 2009 17:57:55 -0400
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Somewhere in that ball park, George.  I think between 440 -550 cc/min or the
stock N/A engine injectors is what the Ec2 was designed for.  Tracy added
some features such as mode 6 to accommodate those who wanted to use
different size injectors (within a limit).

Smaller injectors can make a smoother idle for a car as they more finely
control fuel flow at lower rpm, however, few that I am aware of idle their
aircraft engines below 1200 rpm.  Both Tracy and I idle our older 13Bs at
around 1800-2000 rpm.  So that benefit of a smaller injectors is rather lost
to our use.

Plus a larger primary injector gives you that back up capability of running
on only one pair of injectors, only one size and type of injector to order
or keep a spare on hand and little need to mess with Mode 6 a some of the
advantages I see.

But, part of this "hobby" is doing it "your way" - so certainly no problem
seeing folks opt for smaller primary injectors, just not my personal
preference.

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 George Lendich
Sent: Friday, June 19, 2009 5:44 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: 295cc vs 495 cc was [FlyRotary] responses to
responses, not developing full power

Ed,
295cc + 495cc = 795cc, why not a couple of 400cc injectors as the figures 
suggest, what is the closest to 400cc injectors- is it the 440cc Tracy 
recommends?

The engine won't be going over 7,200 rpm for most applications and the 
495cc secondary Renesis is larger than our needs. I know larger is better 
for the higher RPM as it dispenses larger amounts of fuel over a shorter 
time, however for idle and low power their getting too big.

So I figure for the situation of having them the same size, I wouldn't have 
them bigger than the 440cc Tracy recommends.
George (down under)

> 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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