How does air-fuel ratio affect engine performance?

An excessively high air–fuel ratio may produce high pumping loss, high peak cylinder pressure, and high compressor outlet temperature. An excessively low air–fuel ratio may produce the problems of deteriorated combustion efficiency, high smoke, and high exhaust gas temperature.

What happens if diesel rich air/fuel mixture?

If chemically correct diesel is injected into the combustion chamber, the air-fuel ratio in certain region within the combustion chamber is likely to be so rich that some of the fuel molecules will not able to find the necessary oxygen for combustion and thus produce a noticeable black smoke.

What is a good air to fuel ratio?

about 14.7:1
The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all fuel with no excess air. For gasoline fuel, the stoichiometric air–fuel mixture is about 14.7:1 i.e. for every one gram of fuel, 14.7 grams of air are required.

What air-fuel ratio makes the most 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.

Where is the lean air fuel mixture needed?

Lean Air-fuel Mixture Is Required For(A)Idling(B) Cruising (C)Starting (D)Acceleration. A lean air-fuel mixture occurs when there is more air than the ideal air-fuel ratio. This can be good for fuel economy and emissions but bad for power.

Do diesels run rich or lean?

Diesels can run rich or lean despite having no throttle. The mixture is completely unrelated to the presence or absence of a throttle. In a modern direct injection diesel, the thing that enters the cylinder on the inlet stroke is air (sometimes mixed with EGR). Fuel does not come in on the inlet stroke.

Does lean or rich make more power?

A rich mixture is more common and not necessarily detrimental to your engine. In the case of a slightly rich mixture, you may notice reduced engine efficiency and worse fuel economy, but the rich mixture will generate more power and actually burn cooler.

What is the best fuel ratio?

14.7:1 ratio
The 14.7:1 ratio is perfect for idling and light throttle cruising conditions as it’s the most efficient mixture possible, meaning the best fuel economy and lowest emissions.

What is a common diesel air-fuel ratio under moderate load?

Dear Maxime Hmr. The the stoichiometric A/F ratio is the ratio of required theoritical air consumption to fuel consumption for all the available oxygen is used to burn the fuel completely This ratio is called the stoichiometric air-fuel ratio. This ratio is about 14.5:1 for diesel engines.

Is 17 AFR too lean?

But that’s in an ideal world, one where every molecule of fuel and oxygen is completely consumed during every single combustion event. In a real engine, a 14.7:1 air-fuel ratio is a little too lean. If you lean out past 14.7:1, all the way to something like 17:1, your engine will run cooler again.