Air–fuel ratio: Difference between revisions

In an [[internal combustion engine]] or industrial furnace, the air–fuel ratio is an important measure for anti-pollution and performance-tuning reasons. If exactly enough air is provided to completely burn all of the fuel, the ratio is known as the [[stoichiometric]] mixture, often abbreviated to '''stoich'''. Ratios lower than stoichiometric (where the fuel is in excess) are considered "rich". Rich mixtures are less efficient, but may produce more power and burn cooler. Ratios higher than stoichiometric (where the air is in excess) are considered "lean". Lean mixtures are more efficient but may cause higher temperatures, which can lead to the formation of [[nitrogen oxide]]s. Some engines are designed with features to allow [[lean-burn]]. For precise air–fuel ratio calculations, the [[oxygen]] content of combustion air should be specified because of different [[density of air|air density]] due to different altitude or intake air temperature, possible dilution by ambient [[water vapor]], or enrichment by oxygen additions.

 

 

The original narrow-band oxygen sensors became factory installed standard in the late 1970s and early 1980s. In recent years a newer and much more accurate wide-band sensor, though more expensive, has become available.

 

Most stand-alone narrow-band meters have 10 [[Light-emitting diode|LEDs]] and some have more. Also common, narrow band meters in round housings with the standard mounting {{cvt|2+1/16|and|2+5/8|in|mm|order=flip}} diameters, as other types of car 'gauges'. These usually have 10 or 20 LEDs. Analogue 'needle' style gauges are also available.

 

== Internal combustion engines==