I've been in discussion with twincessna pilots baout LoP operaiton, very good article here:
"Dollars and sense"
Best writeup I've heard on LoP operation, and finally explanation of why RoP is actually worse on engine than LoP. Written by a lycoming engineer and pilot who studied and flew LoP for many years.
. However note that the 25F
ROP line produces much higher cylinder
pressures. Pressure and temperature
equate to wear and tear on your engine.
That’s also why the line representing
25F ROP is the worst place to run
your engine: highest pressure, highest
temperature. The combination makes for
the highest wear and tear for a common
ROP range of about 25-75F ROP.
This comes as a bit of a shock, because this is exactly where I've been taught to operate RoP.
1. lean to peak
2. enrich mixture until 50-100 degree temperature decrease from peak
I certainly notice there's a slight power boost when the mixture is enriched, but i never realized this is actually BAD for the engine. If you're running 50 degrees RoP at 75%, based on this article, this seems like excessive wear and tear on the engine.
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The LoP article mentioned earlier cites this in regards to high DA t/o:
If you're going for absolute maximum altitude or speed, that very flat "peak" in the BHP curve that occurs around 105 to 110 PPH fuel flow will be helpful, and if you're making a high-altitude takeoff, it will be veryhelpful. The BSFC is dropping as you lean, of course, you're getting "more efficient."
The diagram is here: http://www.avweb.com/
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