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.

(a dyno room violation)

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?