This File was found at: http://www.eaa42.org/misc/gregs_show.ppt It has been learned that the authors of this fine piece of work are: Advanced Pilot Seminars http://www.advancedpilot.com/. Old wives tales of leaning:. EGT rises indefinitely with leaning Highest EGT shows leanest cylinder
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EGT rises indefinitely with leaning
Highest EGT shows leanest cylinder
Hottest CHT is leanest cylinder
Running LOP causes high CHT
Running LOP will damage valves
Running LOP will increase cylinder wear
“Gas is cheaper than engine overhaul”
The spread between EGT peaks will be excessive without tuned injectors (or with a carbureted engine), and the engine will run rough LOP.
Avoidance of roughness comes from tuning the injectors so they all peak within 0.5 gph
What can you do with a carbureted engine?
As you lean, the first cylinder to peak is the leanest, the last to peak is the richest.
If cruising ROP, you lean by the leanest cylinder, but
If cruising LOP, you lean by the richest cylinder- because you are on the other side of the Red Box.
And you need an engine analyzer to show you where all this is happening!
Absolute EGT numbers are inexact and of little value – but degrees relative to the peak EGT are extremely important in defining landmarks in combustion for each cylinder.
CHTs are important of themselves
Running ROP or LOP are valid choices, but most pilots running ROP are not running far enough ROP, and are in the “Red Box”.SOME BASICS
Lean by leanest cylinder Lean by richest cylinder
Air flow determines power Fuel flow determines power
Extra fuel retards combustion Extra air retards combust
Carbon monoxide plentiful Minimal CO
Not most fuel efficient Fuel efficient at 20-30 LOP
Engine dirty Oil and engine stay cleaner
Engine runs hot Engine runs cooler
Fuel flow determines power
Engines with 7.5:1 compression put out 12.7 hp per GPH
Engines with 8.5:1 compression put out 13.9 hp per GPH
Max manifold pressure degrees relative to the peak EGT are extremely important in defining landmarks in combustion for each cylinder.
Low fuel flow