What is the best AFR for power?
We mentioned the stoichiometric air-fuel ratio (14.7:1) that is the ideal ratio for lowest emissions, but this isn’t the best ratio for power.
It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1..
What is a good AFR at idle?
If you prefer better PERFORMANCE then we suggest to run an AFR of 14:1 or even richer to around 13.5:1. Most stock to slightly modified engines will run just fine at an AFR of 14.5:1 and yield better MPG. If you prefer better PERFORMANCE then we suggest to run an AFR of 13.5:1 or even richer to around 13:1.
What AFR is too rich?
When an air/fuel mixture has too much fuel, it is rich. When there is not enough fuel, it is lean. An AFR higher than stoich = lean. An AFR lower than stoich = rich.
What is a safe AFR?
Air/fuel ratio (AFR) is, unsurprisingly, the ratio of air to fuel injected into your engine. … Maximum power is usually found between 12-14:1, but this may be too lean for safety on many engines. For maximum reliability at full power, air/ fuel ratios from 10.5-12.5:1 are considered best, depending on the engine.