Mailing List flyrotary@lancaironline.net Message #59229
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] renesis injectors
Date: Sat, 17 Nov 2012 08:43:32 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi  Steve, I attempted to verify your math but believe I am missing a crucial factor - injector opening time at 6500 rpm
 
Check my math:
 
10.6 gal/hr = 10.6/60 = 0.17666 gal/second = 0.17666/1000 = 0.00017666 gal/msec flow for all four injectors combined
for an "average" of 0.00017666/4 = 0.000044166 gal/msec per single injector
 
Taking 0.000044166 * 4(injectors) = 0.00017666 gal/msec = 0.00017666*1000 = 0.17666 gal/sec * 60 sec/1 hr = 10.596 gal/hr, so that checks
 
 
Now since there was no different opening times given for the injectors at 6500 rpm, I have to assume the opening time was the same as at 5265 rpm (4.4 msec - which is not likely to be correct).  But, following this assumption - then the increase for the flow at 6500 rpm is simply the ratio of   6500/5265*10.6 gal/hr = 13.086 gph a bit short of the 20 gph figure. 
 
So , I strongly suspect the injector opening time would increase at the higher rpm (it does on my rotary) which would account for the increased flow  - did you happen to measure the injector opening time at 6500 rpm?. 
 
Ed
 
Sent: Saturday, November 17, 2012 1:26 AM
Subject: [FlyRotary] renesis injectors

Charlie,

 

My Renesis engine on the test stand uses the same injectors that Richard has.  Today, I recorded some data that should indicate whether or not these injectors might work for your application.  At 23" MAP, fuel pressure of 40 psi, and 5265 RPM, the fuel flow was 10.6 gal/hr and the pulse width on all four injectors was 4.4 ms.  From this data, it appears that those injectors should support a fuel flow of slightly over 20 gal/hr at 6500 RPM with an injector duty cycle of less than 80%.  It would be good if you (or anyone else) would independently check if my calculation is reasonable.

 

Steve

 

 

Hi Richard,

The only info I could find on the green ones seems to indicate that they are 230cc. I can't find numbers for the brown, but based on the model
number, they are probably slightly larger. I suspect, but don't actually know, that I need 400+cc(normally aspirated Renesis). The yellows are somewhere between 380 & 430 cc, depending on where you look & what pressure they run at.

Thanks for checking, & if it turns out that my research is wrong on the flow figures, we'll need to talk further. :-)

Charlie

Charlie,
are you still looking for injectors?
Would the ones in the picture of any help?
They are out of a 2009 2nd Gen Renesis. The numbers are: green 827 12 , 297500-1220 .
Brown 827 08 , 297500-1230 .
I can not interpret these number.
Richard Sohn
N2071U

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