What is the air fuel ratio?
Short answer
- Definition: mass of air supplied divided by mass of fuel burned
- Stoichiometric value: about 14.5 kg air per kg fuel for complete combustion in a CI engine
- Purpose: ensures complete combustion; excess air prevents CO and smoke
- Effect of too little air: incomplete combustion, CO, unburnt carbon (smoke), lost heat
- Measurement: deduced from air-fuel ratio by mass and exhaust-gas analysis
- Theory source: Reeds Vol 3, Combustion & Stoichiometry
Full answer
The full answer explains each point step by step, with the regulations and figures behind it and the discussion from other candidates. It is in the MEO Class II section of the Marine One forum, open to members enrolled for the MEO Class II exam.