Work out air fuel ratio instantly with clear inputs, formula shown and shareable results.
Air fuel ratio is air mass over fuel mass, and lambda is that divided by the stoichiometric ratio — 14.7:1 for petrol. Lambda 1 gives the cleanest emissions for a catalyst, while full-load operation is deliberately run rich at lambda 0.85-0.9 to control combustion temperature.
Air fuel ratio
AFR = air mass / fuel mass; lambda = AFR / stoichiometric AFR
Excess fuel evaporates and cools the charge and the exhaust valves, protecting against detonation and thermal damage to the turbine and catalyst.
Yes. It is 14.7 for petrol, 14.5 for diesel, 9.0 for ethanol and 17.2 for methane, because the carbon-hydrogen ratio differs.