Datalogging Parameters - McLaren

This brief guide will provide you with descriptions of each logging parameter. Click on the parameter for an expanded view. Some helpful conversions are located at the end.

This is a measurement of how many revolutions the engine makes per minute.

Relative load is the bases for many calculations within the ECU from boost control to fueling. It is the result of airmass calculations. Typically 100% would be the airmass ingested by the engine at STP. It is not uncommon to see a relative load of 200+ in turbocharged applications.

Ignition timing is an offset measurement in degrees of engine rotation from TDC (Top Dead Center) at which the spark plug is fired. Positive timing values are degrees before TDC, negative values are after top dead center.

This is the absolute pressure inside of the intake manifold. This is a direct pressure measurement from the sensor located on the top of the intake manifold.

This is absolute pressure, to calculate boost pressure subtract ambient pressure from this value.
- e.g. 2500hPa Manifold Absolute Pressure - 1003 hPa (Ambient Pressure) = 1497hPa of boost pressure.
To convert hPa to psi multiply hPa by .0145.
- 1497.00hPa x .0145 (psi/hPa) = 21.71psi

This measures the air pressure after the intercoolers on each bank. They are direct measurements from the pressure sensors located on the intercooler outlet. These can be used for diagnosing large boost leaks as well as compressor surge.

This is measured in absolute pressure.