Mailing List flyrotary@lancaironline.net Message #15853
From: Tracy Crook <lors01@msn.com>
Subject: Re: [FlyRotary] Re: P Port fuel Injection
Date: Sun, 23 Jan 2005 18:05:27 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Below are the key points of my and Rolf's previous comments (at least I think so)
 
Tracy wrote :
One important thing to note is that the air volume in the long runner can be larger than the intake charge at low throttle.  This makes it virtually impossible to properly time the injection pulse of a "long distance injector" without knowing the future, if you get my meaning.
 
Tracy  (marking this down as #9999 on list of things to try)
Rolf wrote:
The funny thing is, if you spray at the bell mouth, it takes a complete cycle for the air and fuel to reach the chamber. In other word, the timing should be the same, but when you inject it will reach only the next chamber, not the one it would serve if the injector is close to the intake port.

However, I see no problem with this. In fact due to the back flow you may actually get the same effect as you get with a closed intake valve at an RPE, where the fuel has time to evaporate, hence the better fuel burn with a far away injector.

Perhaps you should think about that for a while and get back to me, see what you think. One thing though, I would ask Tracy about his beginning and end of injection cycle relative to the crank angle at idle and at full speed of 7500 rpm. I am very interested in how he timed his injectors.

Regards
Rolf

Tracy now:
If I understand it correctly, we are in agreement about what happens with injection at the intake end of the runner.   However, I DO see a problem with this at low speed where the fuel is delayed a full cycle  - "Shitty throttle response" to put it in non engineering terms.   It is my guess that P Port vs Side port is a non factor in this matter.
 
In the EC2, I start the injection cycle slightly before the intake port opens.  In the industry literature, some advocate starting it even sooner. 
 
I did some limited testing of injection timing but found no improvement over what I tried first.  None of these tests were with "Far end " injectors however. 
 
As I said before, I'll mark that down as #9999 on my list of things to try.
 
Tracy (so many experiments, so little time)
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