Hold it in the bottom position and you are shown the Maximum, Minimum and Average for the 5 or 10 second period. This is useful to see how stable the swirl was. Rugged aluminum and stainless steel design with 20,000 RPM rated bearings designed to hold up in a shop environment. Low friction bearings provide for more repeatable readings. The Swirl Meter mounts between the bore adapter and the flow bench and records the gross axial, circular motion of intake.
Custom paddle wheel sizes and designs are available from Performance Trends.
Record the Swirl RPM as you run your flow test and record CFM on the intake port. Some users make 2 tests, the first without the Swirl Meter to more accurately record CFM without the slight restriction, then another test with the Swirl Meter to record Swirl RPM only. You may want to check the difference in CFM with and without the meter on your heads and decide if 2 separate tests are necessary. Tests have indicated that you can have too much swirl for some engines, and some successful engine builders actually design for low swirl. Do not simply design for maximum swirl without regard to flow or how the engine behaves on the dyno.