Positive pressure flowbench

[Boosted2.0]

Neat bench! I have a bi-directional bench too, although with a very different air pump design. Yours is a lot simpler and more elegant.

Not sure I understand your test rig however. Are you using your airsource to pressurize your plenum and using the combustion chamber to blow down through the bench and testing it that way? Are you making a port adapter for your bench and bolting the inlet port of the head to the bench and exhausting out the valve? If the latter, how are you simulating cylinder wall?

[larrycavan]

Tom. Take a look at this. It discusses choked flow of gasses and its mass flow in regards to positive pressure and vaccuum.
http://www.therebreathersite.nl/04_Link ... Choked.pdf

I looked at that data quite some time ago. Interesting information there, for sure.

One thing that bothers me about steady state flow bench readings though is the fact they are "steady state".

I was reading about the reported pulsing problem found in the ports elsewhere in this thread. I believe that happens. What bothers me though is the time factor involved with a live engine's valve opening events.

The time events are so quick at RPM that steady state testing, IMHO, leaves us in the dark as to what "actually" takes place in the port compared to when such pulsing actions are witnessed under steady state flow conditions.

There's lag time involved that we can't fully account for. Now because of the fact that a pressurized intake system should theoretically maintain a degree of pressure in the intake port, perhaps the lag time is greatly reduced.

However, as the valve opens, the static pressure in the port must drop, then the port recovers again. That takes time to happen & I wonder just how skewed the data in the linked document actually is when compared to a live running engine... Don't know. Would love to though...