Contour Enthusiasts Group Archives Forums Modifications Zetec Performance maximum volumetric efficiency

Does any1 know this figure? Or have a chart of it?

thx!

Maximum volumetric efficiency on a normally aspirated engine is obviously limited to 100%

Volumetric efficiency is the possible airflow divided by the actual airflow. The possible airflow is the displacement in cubic inches times the RPM divided by 3,456 (to convert to cubic feet) so a 2L engine at 3000 RPM could flow 106 cfm at 100% volumetric efficiency.

Since our cars have a MAF and a scantool can read the MAF and give an output in pounds per minute (with temperature from the IAT), you can essentially read the actual CFM at any RPM (and load).

Typical volumetric efficiency on a stock four cylinder is around 70%-75%.

Well. this I know already.

Problem is I need to know either the Volumetric efficiency, maybe someone had the figure....

Measuring it on the MAF only gives the voltage AFAIK.
Then I need the voltage/air flow chart to convert the voltage to CFM.....

So basically I'm stuck here..............

I do have a OBD2 scan tool, but it only show the voltage on the MAF.