Where do you put your pressure tap?

[Donnie1126]

Today I tried the middle of the bore and a place tapped into the top of the bench into the plenum under the test stand.I got basically the same reading. Is there any area that's basically the best?Does it have to have 4 equally spaced 1/32" holes around it like the MSD bench calls for?Thanks

[84-1074663779]

Measuring static pressure in a fast moving air-stream is not a trivial problem, but when the airspeed slows in a plenum it is much easier.

The classic solution is a pitot static tube with four pinholes, the pitot tube pointing straight into the airflow. If the probe can be moved around without significantly effecting the measured pressure it is probably reading the correct static pressure.

[Rick360]

I have had mine in the upper corner of the top plenum where the air is still and avoids the problems mentioned by Tony. I just recently modified it to a tube circling the outer corner of the plenum with a number of small holes in the tubing for an average pressure throughout the plenum. I think this will be a little better, especially on very high flow heads.

Rick