flyrotary@lancaironline.net Mailing List Archive

Steve,

The values that are 0 are in the column for manifold pressure. The column for the MAP correction has numbers like you are describing. Plus numbers for above the mid point and negative numbers for below the mid point. But without manifold pressure or RPM numbers, I don’t understand how the computer can figure out which bin to select. With all them 0, it would be some kind of random unless the program has a way of attaching a bin to a bin.

Bill B

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of sboese
Sent: Friday, October 16, 2009 7:16 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing power?

Ed & Bill,

If I understand correctly from discussion with Tracy, the default value of 128 for a MAP table value is what you would read directly from the data stream. The 128 is reported as zero on the EM3 with positive values indicating enrichment and negative values indicating leaning. Values of zero on the EM3 are values which have not been changed from the default.

Steve

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Friday, October 16, 2009 4:49 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Stoich A/F Ratio?? : [FlyRotary] Re: where's the missing power?

Ok, I understand now Bill. I think Al answered your question on how far from 14.7:1 to 9:1 on his controller of his 3 rotor – That’s the only information I am aware of about how much twisting of the manual mixture control it may take. I can simply state that with the mixture Knob at 3:00 its too much fuel for my N/A turbo block – so I would say Al’s information sounds reasonable to me.

Unless Tracy has really changed things with the EC3, there are NO manifold pressure values in any bins (columns of the table) – the manifold pressure (when used) is converted into a “bin” pointer which points to the appropriate bin (numbered from 0 – 128) for that corresponding manifold pressure). That “bin” selected by the manifold pressure value of the engine then contains a fuel factor value represented by the value (height) of the bar in that bin. I believe Tracy’s default value is 128 which theoretically would give a 14.7:1 air/fuel ratio. Going above that value enriches the mixture and below leans it.

IF there are zeros for the values of any of the bins then that says there is no Map correction Table (MCT) correction factor used for that bin. . So if the values of zero are valid, I would assume that for those regions the fuel needed must be derived solely from some other parameter – like RPM with the manifold pressure value only acting as a switch (above below 13Hg for example)

But, if that is indeed the case then I’m still a bit surprised there are no MCT values for rpm.

There is the possibility that somehow the MCT values for those bins were set to zero accidentally, but as you so rightly surmised, only Tracy can answer the question you have.