Mailing List flyrotary@lancaironline.net Message #46679
From: Al Gietzen <ALVentures@cox.net>
Subject: RE: [FlyRotary] More progress, more questions....
Date: Sat, 27 Jun 2009 07:31:39 -0800
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

I am concerned about some sputtering that is present around idle.  It is

generally pretty smooth, but sputters too. Not sure what is causing it

yet.  Thoughts?

 

Don’t know exactly you definition of sputtering, But could be a combination of factors, including some mixture tuning required. My engine is smooth down to about 1500, then begins to miss the occasional beat as I slow it further, and gets a bit rough down at 1000. It might help if you can figure out why you have to ‘pump’ the throttle to make it slow down.

 

I don’t have a clue about the RPM inconsistency, but on the photo of the EM2 panel it looks like voltage is 11.1, but can’t tell for sure.  Did you not have the field current on the alternator? If you tune the engine with the voltage at about 14.0; then run at 11, it will be out of tune, and probably idle rough. This becomes more of an issue with the small power wires and associated voltage drop.

 

Next, in the documentation for the EC2, the diagrams and part of the

text it shows that most of the wires should be run using 22 and/or 20

AWG wire for the connections.  However, in ONE place in the document it

states that the power wire to the coils should be 16 AWG.

 

I don’t think that’s an inconsistency, perhaps a misunderstanding.  I think the 22 and 20 ga. refers to all the wiring between the PCM and the EC2; The power leads to the coils and injectors are a separate issue. As Ed points out, there will be undesirable voltage drop in a 20 ga, perhaps worse than Ed mentioned because the peak currents, especially for the injectors, will be greater than 10A.  I’d also be a bit concerned about the heating in the wires enclosed in a tube; although I’m not sure what the ‘average’ current is.  If it is 10 amps the 20 ga. is going to get warm up; which increases the resistance, etc.  I know it’s a PITA; but if it were me, I’d bite the bullet and change to 16 ga.

 

Oh, a final comment on progress.  My cooling continues to impress me.

 

I’m impressed with your cooling as well.  Mine is good now, but I had to make a few changes after first flight to get it there.

 

Poco a poco, se va lejos,

 

Al

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