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I discovered the log viewer's scatter plots this evening. It's a way to visualize how various parameters affect each other. It is fairly obvious that I can add in a lot more advance.
The task for the next session is to set the whole table to 20*. Run the throttle up and down a couple times, increase 2* and repeat. The end of the day should find me with a graph showing RPM against advance for a range of throttle positions.
Lehanover@aol.com wrote:
Not until October when we move back to Zephyrhills. Big airport 10 minutes away KZPH.
You have too many knobs to turn. This thing should run perfectly once it's dialed in. All of the tuning we are talking about is idle and just off idle. So the load of the prop is a constant for any particular RPM (plus or minus air density) and so-on. So I would bump up the timing until there is no RPM increase and then back up 4 degrees and watch the temps for a few minutes. If no change book that advance number and move on. Idle mixture and dismal cylinder filling is just the same as tuning a lawn mower. Not much going on and not a huge load. At idle and off idle you will not see maximum cylinder pressure at 50 degrees where you want it at high throttle settings. So little energy is available that the expanding chamber drops the pressure rapidly. Probably not reaching 50 degrees with any pressure left. EGT may not even move the gage. All I need from idle is to maintain 2,200 RPM, no quitting and no surging. My idle jet is the biggest I can find, and idle is very much over rich. This for the end of the long straights where the engine is screaming (9,600 RPM) and the throttle snaps shut for braking. The only apex seal lube is in the fuel. So the idle mixture lubes the seals.
And, you get a nice fire ball and an occasional howitzer like explosion.
The crowd loves it. Probably not a good idea for aircraft use, but then you should have some fuel flow at closed throttle to lube the seals. Just don't close the throttle all the way. My Fiat engines had 14.5:1 compression. Cranking pressure was 245 pounds. Hot leak down was zero. You had to start it at idle, lest the starter just stop turning.
Never detonated a single engine with the same driver that could detonate a rotary. Because the cylinder filling on the Fiat was so poor. The 2 throat carb had a 17mm bore and a 23 mm bore. So, the effective compression dropped down right off idle. I ran 110 avgas in that one. Accused of running super fuel blends because of watering eyes for anyone close by. It was oxides of nitrogen. The timing was 36 degrees at race speeds from a crank trigger. At low speed it was 5 degrees from a near stock distributor.
Cylinder filling is everything.
Lynn E. Hanover In a message dated 7/17/2012 11:25:47 A.M. Eastern Daylight Time, echristley@att.net writes:
Lynn, I can't wait to fly down to Florida and let you play with this engine management system.
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