Innovate Motorsports LC-1 - Manual (Page 3)

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1 Overview
The LC-1 is a stand-alone Wideband Controller used to measure the Air/Fuel Ratio (AFR) or
Lambda for an engine. For gasoline-driven engines, the theoretically optimal air fuel ratio is 14.7
pounds of air for every pound of fuel. At this ratio, theoretically, all available oxygen in the air
combines with all available fuel. This ratio is called the stoichiometric ratio. Stoichiometric for
different fuels are as follows:
Gasoline 14.7
LPG (Propane) 15.5
Methanol
6.4
Ethanol 9.0
CNG 17.2
Diesel 14.6
The measurement Lambda is the actual air fuel ratio over the stoichiometric ratio. A Lambda
measurement of “1” equates to the air fuel ratio of 14.7 (for gasoline engines). When Lambda is
less than 1 the engine runs “rich”, i.e., unburned fuel exists in the exhaust stream. If lambda is
greater than 1 the engine runs lean, i.e., free oxygen (0
2 ) is present in the exhaust. Depending on
the engine, maximum power is typically delivered when the engine runs slightly rich (for example
at lambda values of 0.8 to 0.9 for most engines). This instrument provides a means to measure
the actual air fuel ratio or lambda in the engine in operation directly from the exhaust. For this a
special wide-band oxygen sensor is used to measure the lambda value derived from the oxygen
content (or lack thereof) of the exhaust gases.