Why is LOP (lean of peak) controversial?

On 28 Sep 2006 07:58:18 -0700, "Doug"
wrote:

One thing no one has mentioned is LOP may not be possible with
carbureted engines. The flows to each cylinder just aren't consistent
enough to make it work.

This may not be a problem if you're flying with autogas. I've noticed
in my Warrior that leaning too much causes roughness and missing when
flying with 100LL. I'm sure that everyone else has noticed the same
thing. When running on autogas, you can lean aggressively and the
engine continues to run smoothly. I've wondered what causes the
difference, and how much I can take advantage of it without proper
instrumentation. I've read that generally you can lean as aggressively
you want as long as you're below 75% power.

I've wondered if the smoothness might be due to cleaner plugs, but
100LL causes lean roughness even with new plugs. I've also wondered if
those ads that the oil companies used to run about their gasolines
making your car's engine run smoother due to better fuel distribution
suggest an explanation of the difference. I've suspected that this
might explain it. If true, it might be another reason to get the
autogas STC--better fuel economy.

RK Henry

: This may not be a problem if you're flying with autogas. I've noticed
: in my Warrior that leaning too much causes roughness and missing when
: flying with 100LL. I'm sure that everyone else has noticed the same
: thing. When running on autogas, you can lean aggressively and the
: engine continues to run smoothly. I've wondered what causes the
: difference, and how much I can take advantage of it without proper
: instrumentation. I've read that generally you can lean as aggressively
: you want as long as you're below 75% power.

... *and* 400 degrees CHT.

: I've wondered if the smoothness might be due to cleaner plugs, but
: 100LL causes lean roughness even with new plugs. I've also wondered if
: those ads that the oil companies used to run about their gasolines
: making your car's engine run smoother due to better fuel distribution
: suggest an explanation of the difference. I've suspected that this
: might explain it. If true, it might be another reason to get the
: autogas STC--better fuel economy.

I haven't really noticed much different in mine whether running autogas or
100LL. One possible reason could be vapor pressure. I bought the vapor pressure
tester along with my autogas STC just so I could check for vapor-lock in the summer.
The 100LL has a slightly lower volatility than the autogas, at least here. If to
autogas vaporizes better and easier, it could do it sooner out of the carb jet and
make for a better distribution.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
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