I posed this question because for years I had assumed that lean mixtures
burned hotter. Then I went to a seminar put on by a fuel guru here on
the West Coast who was explaining many facets of fuel production, octane
measurement, and properties of different blends, etc. He opened my eyes
to a "totally new concept", as Gallager would say.
Lean mixtures actually burn with less temperature, but because a lean
mixture also burns slower, the heat is held to the piston for a longer
period of time, hence "Melt Down."
I have found that much of the detonation and melted pistons that I have
experienced can be traced to less than adequate cooling system. That was
certainly the case Speedweek. If I had been in the driver's seat it
probably wouldn't have happened. We run a "Dial-a-Jet" which allows
adjustment while under way. I monitor the engine temp, if I'm not to
busy with directional control, and adjust jetting as needed. Jeff is
still learning!
Tom
Jim Dincau wrote:
>
> ----- Original Message -----
> From: Thomas E. Bryant <saltracer@awwwsome.com>
> snip
> > Gasoline is, as has been stated, critical on A/F mixture. 14.7:1 is the
> > desired A/F ratio considering exhaust emissions, but 12.0:1 to 12.5:1 is
> > the range that gives the best power. It is said that the most combustion
> > heat is generated with A/F mixture about 10% rich. Assuming this is
> > true, Why do lean mixture burn holes in pistons?
> >
> > Tom
> >
> Is this a test? oh well here goes my 12 EE.
> Could it be that the excess oxygen combines with aluminum just as well as
> with fuel?
> Jim in Palmdale
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