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From: n295vv@aol.com

Well, as long as we are on turbo TIT and such, I thought I would throw this
against the fan:

Neil Pobanz, famous Guru of Bonanza fame across the USA (and the world), told
me that you had two choices on the Continental TSIO-550-- "Lean and buy
cylinders, or don't lean, and get long cylinder life.  Cylinders cost $9000,
you make the choice"  

I did some mental calculations, including amortization on the 9K, cost of
downtime, savings per trip, etc, and I decided at the outset not to lean.  Oh,
I have leaned somewhat when safety deemed it because of presssure altitudes,
but generally, I don't lean.

Not that this makes any difference, however, because I built my IV to fly
fast, and I fly at about 85% whenever I fly.  My cylinders are certainly not
having problems from  85% power settings, because the TIT 's are seldom over
1550 degrees, and the head temperatures are in the low 300's.

Neil Pobanz has cited several planes that the owners are agressively non-
leaning, and several are into the 1800-2000+ hour range with no cylinder
problems.  Since a $9000 cylinder job at 700 hours seems to be the norm, these
guys have saved about $18,000 minus some fuel bills.  Plus, they have had the
advantages of nearly full power in all their operations.

Since the cylinders are washing gas into the oil on a regular basis, I open up
the oil fill cap at the end of each trip to allow gas to evaporate from the
crankcase.  I also change the oil every 25 hours or so.

This is a personal decision, made for me only.  I am not advocating it for
anyone else.  If I make it substantially past the 700 hour wall without bad
cylinders, I will be happy.  If I make it to 1800 hours, I will be very happy.
Flying in the yellow and happy.

David Jones
Pecatonica, Illinois