Orval Fairbairn wrote:
In article ,
" jls" wrote:

Just wondering what the collective experience is, if any. I know
of
several people with the 160 HP O-320 using mogas, but they're
careful about
vapor lock in summer. Used in experimental aircraft, of course,
not in a
certified aircraft. Keep in mind too that the CR is 8.5 to 1.

A friend wants to do it and I told him I thought it was ok as long
as he
monitored his CHT and EGT on all 4 cylinders, used 92 octane only,
and took
off and landed on 100 LL.

What do YOU think?

The O-320 160 hp was originally certificated on Grade 91/96, so the
above operation sounds conservative.

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I mix about 15 - 20 % 100 LL with in my tank of mogas and get leaded
gas like the Lyc. was designed for. EAA had some research on this
years ago and found that the octane rating was higher with this
mixture. I have used it for years with no more problems than 80/87 or
100 LL. I have seen vapor lock with all of them - no one more than any
other. When you park in the hot sun and the fuel gets hot, you need to
run the boost pump until it cools down.