Originally Posted by
sailorbob
There is not a fixed A/F ratio for maximum power as every engine behaves differently. You typically find that maximum power is richer than stoichiometric but you need to run even richer than this for cooling.
Absolutely correct. However, aim to start with 12.5:1 as this is the figure that gives the best results on the widest array of engines. Be aware though that max power is NOT what you should be aiming for when mapping. But it at least answers your question.