''With compressible flow things get more complex. The square root law still applies but ONLY when the upstream conditions are held constant. In other words to increase the pressure drop without changing anything else we have to change the downstream conditions i.e suck harder. If we change the upstream conditions then the density of the fluid changes and so does the mass flow rate.''
l'll take a stab
if you push test exhaust (blow outward) the density/''upsteam'' condition changes thereby affecting mass flow. you are ''supercharging'' the exhaust
according to this reasoning it would be better to test by pulling through the exhaust port.
but what i don't understand is the effect of the adapter..if i just bolt the manifold through the head and use that to pull the vacuum i made the port quite a bit different.
*noodle cooking again*
cheers