General

Stoichiometric

The chemically ideal air-fuel ratio (14.7:1 for gasoline). At this ratio, all fuel and oxygen are fully consumed.

Why it matters

Stoichiometric is the baseline for understanding rich and lean conditions. Engines run richer than stoich under boost for safety.

AFR of 14.7 or lambda of 1.0 during cruise. Under WOT boost, engines target richer (lower AFR, lower lambda).

The ratio of air to fuel in the combustion chamber. Lower number = richer (more fuel). Higher number = leaner (less fuel).

Another way to measure air-fuel ratio, expressed as a ratio where 1.0 = perfect stoichiometric combustion. Below 1.0 = rich. Above 1.0 = lean.

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