I read that the air fuel ratio of 14.7 is what you want in a car. But then why do people say lean is mean and things of this nature. can you go faster with a ratio that is leaner than this? And if so why is this possible? Can someone please explain. thanks.

 

14.7 parts air and 1 parts fuel is the theoratical "perfect" ratio for combustion. At that ratio there is no wasted oxygen or fuel molecules, all are burned. In a lean condition, such as 18:1, there is not enough fuel. In a rich condition, such as 13:1, there is extra fuel left over.

For normal driving, 14.7 is really what you want. At wide open throttle, it's actually better to have extra fuel. Opinions vary on how rich, but personally I tune for about 12.5:1.



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Jester why is it better to have more fuel at wot, what effect does having the extra fuel have if 14.7:1 is theoretically perfect? Also how do you go about having 14.7:1 under normal driving and 12.5:1 under wot, is it in the prom programming? thanks for any help.