Innovate Motorsports LogWorks 3 - Manual (Page 131)

LogWorks3_Manual_1.01.doc - 131 -
13 How LogWorks unit conversions work
To automatically convert units, LogWorks uses a special library file named Conversions.txt.
This file must be located in the same folder as the LogWorks.exe file.
You can manually extend the number of conversions LogWorks understands by editing this file.
Additional conversions for many units can be found here:
www.onlineconversion.com
NOTE:
Avoid multiple conversions back and forth. A computer has a limited resolution for
numbers which creates rounding effects, and these rounding effects add up after a few
conversions and will create inaccurate data.
13.1 Conventions on unit names
For LogWorks to understand a conversion, certain conventions must be followed:
13.1.1 Temperature conventions
Temperature measurements are in degrees Celsius, degrees Fahrenheit or degrees Kelvin.
Celsius units are named degC
Fahrenheit units are named degF
Kelvin units are named degK
13.1.2 Pressure conventions
Pressures used in engine diagnostics are either in gauge pressure or absolute pressure.
Gauge pressure is typically what a boost or vacuum gauge measures. It is actually the pressure
difference to the current atmospheric pressure, not the actual pressure itself.
Absolute pressure is the pressure above absolute vacuum. This is what most MAP sensors
measure. MAP stands for Manifold Absolute Pressure, not Manifold Air Pressure as a lot of
people think.
The fueling or AFR value of an engine is a measure of the ratio of the mass of air entering the
engine divided by the mass of fuel. The mass of fuel, being a liquid, changes little with pressure
or temperature. Air, being a gas, changes dramatically. Doubling the absolute pressure with no
change in temperature, will double the mass of air entering and therefore would also require
double the fuel for the same AFR. The air mass is dependent on ABSOLUTE pressure in the
manifold, not gauge pressure and is also dependent on temperature.
Pressures are mainly measured in PSI (US, pounds-per-square-inch) or kPa (international, kilo-
Pascal). The kPa value is by convention an absolute pressure value.
To distinguish between gauge pressure and absolute pressure it is common to add a ‘g’ at the
end of a gauge pressure unit and an ‘a’ at the end of an absolute pressure unit. If the ‘a’ is