best AFR for Power??

flyfish said
I use lambda on my AFR gauge, because it normalizes the air fuel ratio by taking into account the stoichiometric coefficients of the combustion reaction. You can use AFR if you like...I just like lambda because its what I'm used to. Here is a chart I stole from somewhere online that helps to show the lambda and AFR scale (the highlighting was not from me).
View attachment 1715811302

Thanks for posting that chart. It's an important reminder that AFR's don't necessarily mean anything without knowing what fuel the engine is running. If one person says their car runs it's best mph at 12.0, without knowing the fuel type, what does that tell you? Even 10% EtOH makes a difference.