The ideal mixture

The ideal ratio of air and fuel for a petrol engine is present if 14.7 kg of air come with 1 kg of fuel.
The ideal ratio of air and fuel for a petrol engine is present if 14.7 kg of air come with 1 kg of fuel

The ideal ratio of air and fuel for a petrol engine is present if 14.7 kg of air come with 1 kg of fuel. It is also called a "stoichiometric mixture". In this connection the quantity of air supplied for the combustion corresponds exactly to the theoretical air requirement.

This ideal mixture is also identified by the Greek letter lambda (λ). Only when this ratio is present is a complete combustion ensured and the catalytic converter can convert the exhaust almost entirely into environmentally-compatible gases.

Today nearly all petrol engines are operated with this mixture. For other fuel types the air-fuel ratio changes.

 

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