volumetric efficiency

[Mattias Nyberg]

Measuring the real air flow is not easy. The air flow
meter is sensitive to swirl turbulent flow. Also the
flow in an engine is pulsating. To measure corectly, the
air flow meter must have laminar, steady flow, which
is never the case in an engine. To overcome the proplem
the air flow meter has to be calibrated in the position 
where it is going to be used.

For example, in our lab we have a hot film air mass flow 
meter, which was sent away for calibration ($150). After the
calibration we mounted the MAF in our lab and it measured
the air mass flow with an error of about 25%. We concluded
this when we got an volumetric efficiency of 1.1 !

Mattias Nyberg