I see a service ceiling of 18,000' published by Lancair.  Is that a legally binding limitation? 

((I don't know of any legally binding reason for that unless they include an oxygen system that is limited to 18,000.  That would be a legal limitation.  But then it might be better called an "operating limitation" since the term "service ceiling" usually is when the rate of climb drops to less than 100 ft/minute. 

 

Are the following numbers credible for a 10:1 compression IO-550 with one Light Speed Plasma ignition? 

   KTAS   gph
   263   19.8 (flat out)
   253   17.1
   241   14.5
     :        :
   180    7.8

((I can't comment except for the 19.8 GPM "flat out".  If you are assuming it is 75% power ROP, then it sounds logical.  If you are saying flat out means at sea level, full throttle and max rpm, full rich the number would be closer to 30 GPH.

 

For a fairly stock IO-550N installation (e.g. 8.5:1) at 8,000', what numbers would you see LOP, with and without electronic ignition?

((fuel flow would probably be around 14, but I can't comment on the speed))

 

Since much of my trip is above 8,000', what would the above performance numbers be at 12, 16, and 18,000'?

((again, don't know about speed, but at 12,000 feet I burn about 12.3 GPH at 12,000 and 2500 rpm.  It depends on temperature and rpm.))

 

Apart from keeping CHTs cool, what pilot and maintenance techniques will increase engine life?

((Running LOP most all the time is, I believe, the biggest factor.  Doing that my plugs will go 200 hours between cleaning.  Running LOP will also reduce the peak cylinder pressure, which I think is a big factor for a 10:1 engine.  Some will say to change oil more often that recommended, but I think that won't do a thing.  LOP operation will reduce oil contamination significantly.  And keeping the cylinder head temperature below 400 will help a lot))

 

How many cylinders would I expect to replace in 2000 hours of flying careful LOP?

((You should expect no cylinder service in 2000 hours running LOP.  But the 10:1 compression will increase the loading, and probably wear, on the rings, so I would change that to "you can HOPE that there will be no cylinder service"))

 

What time-frame did you guys start seeing problems with Performance Engines?  Any thoughts on Lycon engines?

((I've been running engines built by Lycon for many years and have been satisfied.  Not perfect, perhaps, but good enough that I'm "satisfied".  But that's always been with Lycoming engines - after all, the "Lyc" in Lycon is capitalized, but the "con" is not....:-))