Ernest,
Someone could correct me, but I don’t
think the EC-2 moves the ignition timing a whole lot. Since you are
inventing this tuning for your system, why don’t you set your timing at a
constant spot, say 20 degrees like Lynn
suggested, and then tune the fuel map. After you get the fuel pretty
good, then you can go back and try and improve it with the ignition. Then
do another pass with the fuel. You should be there at that point…well
you can always hope!
You didn’t say anything about the
fire extinguisher….that could be more important than the tuning! If
you think your wife was upset over the exhaust smell, wait till you smoke
damage her new wallpaper! :>)
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Ernest Christley
Sent: Thursday, July 07, 2011 7:57
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: fuel flow
On 07/07/2011 06:51 AM, Lehanover@aol.com wrote:
I suggest adding a bunch of fuel
first. Then lean back to take off power at about 50 to 100 degrees rich of
peak power/EGT, or under 1600 degrees. Or F/A in the 12s. We have people in
charge of warping apex seals. You do not need to cover that again.
Roger that. The issue is knowing what number to
put in to get bunch-o-fuel. I thought my VE numbers set to over 100 would
be good. The tuning software came back at me with suggestions of 175
after the short power run.
I sense a lack of check list. I
detect more than one change at a time.
That sixth sense you've got there is still
working. This computer does a lot of stuff and I have had a good portion
of that set wrong, especially when I'm exploring new areas of the operating
regime where I don't really know what the numbers should until I've run the
engine there. Things are slowing down and getting more stable now,
though. With longer runs and more power, I'll have to be more careful so
I don't take the apex seal warper's job. BTW, is that a union gig?
Is there at least a 50 pound CO2
fire extinguisher standing there with the pin out?
Timing at 20 degrees BTDC is fine up to 9,000 RPM on
low octane pump gas. Remember pump gas burns a bit faster than avgas. We are
looking for best cylinder pressure at about 50 degrees after TDC not 18 degrees
like a piston engine. Turbo engines at high boost can be at 10 degrees BTDC.
Too much advance kills HP and adds heat.
I think I should dedicate the next few runs to getting a better ignition
table. I don't know if you've seen a MegaSquirt setup, or if other
controllers are similar, Lynn,
but the tuning process consists of modifying a grid of numbers with RPM and MAP
values along the axis. There is a real-time ticker that shows where the
controller is picking the current number out of the graph. With the arrow
keys on the keyboard, you can move a separate ticker around and then use other
keys to bump the grid values up and down.
Up to this point, my tuning has consisted of letting the computer do it.
Here is a good video of that process:
http://www.youtube.com/watch?v=wLyk58f-u9I
The manual tuning process, as I understand it, is to pick one of the tables.
The ignition table in this case. Let the engine warm to operating temp,
set the throttle and give it a few seconds to settle. Move to the grid
cells surrounding the one where the real-time ticker is and move them up or
down until the MAP is minimized. Move the throttle to a different
position and repeat. An experienced ear could tell me immediately that
I'm running to rich or lean or how the advance should change, but I'm still
doing a lot of guessing with the "poke it and see what happens"
technique. Do you have any tricks of what to look for when tuning the
ignition advance?