Mailing List flyrotary@lancaironline.net Message #44504
From: Tracy Crook <tracy@rotaryaviation.com>
Sender: <rwstracy@gmail.com>
Subject: Re: [FlyRotary] Injectors & Indicated RPM's questions
Date: Tue, 16 Dec 2008 10:31:33 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Ed pretty much nailed the staging question.  Try setting it at about 19 - 20" MP (Mode 7) and see if it works as expected.

The Tach problem sounds like noise on the trigger line from the injector.  Make sure you are on the right side (EC2 side, not power wire) of the injector with the trigger connection (it will trigger on the noise if on the wrong side).   If there is abnormal noise on the correct side, that could also cause the problem.  

One other possibility is:   If running on primaries only, you may be approaching 100% duty cycle on the injectors at high throttle.  If that happens, there is no trigger and the tach reading will go erratic as you approach this point.  Fix the staging problem and the tach problem will go away if this is the cause.

Tracy  (in EM3 programming hell)


On Tue, Dec 16, 2008 at 2:27 AM, Christopher Barber <CBarber@texasattorney.net> wrote:
Now that I hopefully have my strakes mostly repaired I am able to focus on the engine again.  So, in that vain I have been able to run it the last few days trying to get it tuned properly and hopefully reliably.  We have had some cool weather.....heck, for Houston it has been downright cold dipping into the mid 40's, thus allowing me to run the engine at higher power settings for a bit longer.  Also, based on discussions here last week I am modifying my cooling system a bit...I have had my small hose opening on my rear iron plugged up to this time, but will modify when my new aluminum expansion tank arrives.  Funny, after following rotary stuff for years I missed this apparent cooling convention.
 
One issue I am having is that regardless of how high I push my rpm's it appears that I am only running on the primary injectors.  The EM2 continues to display the asterisk even at WOT.  Also, when I shut down the primaries at high rpm's (well over the staging point....3000 ish?) the engine dies...actually, it dies whenever I shut the primaries off but I would expect that at lower rpm's and idle (kinda rough idle around 1500 rpm, but also kinda expected with a medium street port).  So, to confuse me more in my initial diagnostic I shut off the engine, kill the fuel pumps and place the EC2 in Mode 1, injector diagnostic.  All four injectors fire away....I shut off the primaries and the secondary's chirp away.  I shut off the secondary's and the primaries still clatter on.  This is what I expected, it just is not doing the same thing when the engine is actually running.  Thoughts?
 
Also, a second issue, one I was just starting to try to solve when my strakes became the priority, is that as I approach 6000 rpm on my EM2 display the indicated rpm starts jumping all over the place....1200, 3543, 3333, 2650, 6314.......randomly.  It is doing this even though the engine is still developing more power, obviously over 6000 rpm...as you can tell by the sound and the increased power.  As I throttle back to about 5900 the indicator starts displaying as expected again. Additional thoughts?
 
As always thanks for your consideration and insights.
 
Finally, it is kinda kewl to have the "airport types" stop by to comment on the noise.....music...noise....music....all in the ear of the listener <g>.  Today Gary Hunter, a name well known to most fast glass guys (he is also the crew chief for Bruce Bohanon's Flying Tiger) stopped by and said it sounded "strong".  Wahoo.  Gotta take the small victories.
 
Thanks again.
 
All the best,
 
Chris Barber
Houston

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