Lingenfelter L460240000 Lingenfelter NCC-002 Nitrous Control Center v1.5 - Manual (Page 165)

Appendices 164
9.4 Appendix D: Glossary of Terms
Air to Fuel Ratio (AFR): Air to Fuel Ratio (AFR) refers to the ratio of the mass of air and fuel inside an
engine at any given time. In theory, the most efficient AFR is where there is
only enough air in the engine to completely burn the fuel, also known as the
Stoichiometric ratio. For standard gasoline, Stoichiometric ratio is 14.7. In
most performance applications, however, the Stoichiometric ratio is rarely
targeted during wide open throttle conditions. Maximum power with standard
gasoline is usually achieved with an AFR of 12.8-13.0. Because Nitrous
Oxide (N2O) contains more oxygen then air does, it is able to burn the fuel at
a higher temperature, creating higher pressure in the cylinders and ultimately
more power. While the added pressure in the combustion chambers
increases horsepower, it can also damage the engine if the AFR is not
adjusted accordingly. In general, you should run a richer AFR when the
nitrous is active.
Hysteresis: Hysteresis refers to a margin above or below the set range in which a
component is allowed to stay enabled or disabled in order to prevent the
component from switching on and off rapidly. If a thermostat, for example,
was to maintain a temperature of exactly 72 degrees, it would most likely
overshoot 72 degrees and then undershoot trying to correct itself.
Theoretically, this would cause the thermostat to switch on and off for an
infinite period of time, exhibiting behavior similar to a sine wave function. As
one can imagine, the continual switching of the thermostat would drastically
reduce it's functional life span. For this reason, thermostats and other devices
generally have a built-in hysteresis function that allow them to stay off or on
for longer periods of time. In the case of the NCC-002 Nitrous Control Center,
the nitrous is enabled by several variables for which a hysteresis can be set.
The illustrations below show the behavior of a 5% hysteresis applied to the
maximum and minimum RPM activation thresholds for nitrous through the
NCC-002.
NOTE: These graphs below are for illustration purposes only. The actual
RPM hysteresis value is dependent on the user-defined RPM maximum and
minimum values, as well as the user-defined hysteresis percentage.
As the illustration shows, the nitrous enabled condition remains unchanged
until the user-defined maximum value is reached. The illustration has a user-
defined maximum value set at 16000 RPM. The illustration has a 5%
hysteresis, which is shown by the dotted navy line. Once the nitrous is
disabled, it will not re-enable until the set point minus the hysteresis is
reached.