Airspeed question

[goflo at pacbell.net]

Robert Humphris wrote:
> 
> Renault 5 GT Turbo owner was asking a porting shop about their mods to 
> carb and
> manifold.  They said that they were 70% up on standard flow... which
> they claim to be able to prove, so we will leave it at that...  The bit
> that I am not sure about is on the subject of airflow, when questioned
> they said that "When you put the carb and manifold on the flowbench it
> whistles.  Air only starts to whistle at 300mph, so we know that the
> airspeed is greater than 300mph..."

Air velocity is readily measurable with a pitot tube probe (>$100 US)
and a manometer, or other pressure transducer, which your shop's bench
certainly has. No need to whistle. Reasonable velocity must be
maintained
through the intake tract, not just the choke points, such as carb
venturi.
70% increase in any manifold is very impressive. Not familiar with this
model so no opinion.
Most meaningful test would be to bolt the whole intake tract including
the cylinder head to the bench - measure before and after modification
airflow through the lift range the cam used produces. Then integrate the
lift/airflow curves and compare the difference. This figure will
correspond 
reasonably to net grunt delta, if any, produced by mods.
This applies to intake side. Exhaust considerations  mo' different.
None of the above is Scripture - Well, maybe the parts I stole from
Vizard.
Interested in other points of view. 

Jack