edmechanic wrote:
> Well I have a rather unorthodox view of combustion developed as a
> smog tech. One of my smog instructors said that the difference between
> a rich mixture and a lean mixture is that the rich mixture burns faster
> because fuel molecules closer together and a lean mixture burns slower.
> So the way I look at it is a rich mixture will burn when the piston is
> near Top dead center producing alot of pressure and heat where you can
> do the best work for pushing down the piston.

Any difference in distance (mfp) between molecules is insignificant.
Further, the speed of the molecules is very high compared to their mean
free path.

The flame front speed doesn't vary that much with mixture ratio, at
least over the ratios we are talking about. Also, the burning time is
insignificant in SI engines in terms of degrees of crankcase revolution
angle except at VERY high rpms.