Air/Fuel Ratio Explained
|The Air/Fuel ratio, or A/F, is simply the mass ratio of air to fuel as it enters an engine on its intake stroke. An engines A/F will have a direct affect on engine performance.|
|There are three basic things that your engine must have to work properly. They are fuel, air, and spark. The goal is to have the air and fuel mixed to a point where every last bit of both the air and fuel are usedin the combustion cycle. When we achieve this "total burn" we are in a stoichiometric state. "Stoichiometry" is a term that means that the most complete combustion is achieved.|
All fuels have different stoichiometry. The stoichiometric ratio for gasoline is 1:14.7, or 1 part oxygen and 14.7 parts fuel.
So it's that easy huh? Tune it to 14.7 for the best power right?
No. I wish it was that simple. The 14.7 rule only works for idle, and cruising speeds. Under full throttle load, you would want a "richer" air to fuel ratio. The word "richer" refers to adding more fuel. This is necessary to prevent detonation within the engine.
Every motor is different. Heat, and cold affects air/fuel ratio while driving, and it is constantly adjusted to counter for outside forces affecting on it. The optimum air/fuel ratio for one persons engine could vary greatly from someone elses. It is best to find your vehicles optimum air/fuel ratio on dyno using a wideband oxygen sensor.
Any deeper into Air/Fuel ratio and we'll be starting to tune, so that's a wrap.