Cars · Wiring
Atmospheric Pressure
An overview of atmospheric pressure and its significance in engine management, with reference unit conversions.
Atmospheric pressure (barometric pressure) is the pressure exerted by the weight of the atmosphere. It is a critical variable for ECUs to account for changes in altitude and weather, which directly affect air density and engine performance.
Standard Reference Units
At sea level, standard atmospheric pressure is approximately:
- 14.7 psi (pounds per square inch)
- 1 bar
- 100 kPa (kilopascals)
Conversion Formula
$$\text{Pressure in psi} = \text{Pressure in bar} \times 14.7$$
The primary unit of measurement in modern electronic fuel injection (EFI) systems for manifold and atmospheric pressure is the Kilopascal (kPa).