What is a good air fuel ratio

[Twincharged]

What is a good air fuel ratio?

I seen posts on this board where people are quoting air fuel ratios wrong. When you say air fuel ratio, the ratio is just that x amount of air to y amount of fuel. You will always have more air than fuel. For example 14:1 A/F ratio is 14 parts air to 1 part fuel. It just so happens to be a good ratio for idling and cruising under minimal load. Now let me give you some good examples of air fuel ratios for a force inducted car (turbo/supercharger/N2O)

14.7:1 is the target air fuel ratio while idling and cruising the car under little load.
20:1 is very lean mixture that you will see when deaccelerating like slowing down after a higher RPM.
12:1 is a good WOT (Wide Open Throttle) air fuel ratio.
Some people like to play it safe and run 11.5:1 under WOT. In a sense a richer A/F ratio can act like a chemical way to reduce ignition timing and there for reduce detonation/knock. A richer mixture will burn slower than a lean one. It will also burn cooler and therefore make less HP/TQ.