Tom,
a short information to so formulas.
This formulas are ignoring two parameters.
Speed - we are not running normal road course speed
Aerodynamic - means the airflow the body shape creates in front of the air
intake
Streamliner - a proper design produce a clean airflow - in other words maximum
on air into the air intake - can use a very small cross section opening, due to
this that a speed increase produce by a clean airflow a increase of air through
the opening
Coupe (like your Thumb Special) - if the air intake is behind the open wheels
you get a very bad (full of turbulences and vaccums) airflow in front of your
air intake - the air which goes controlled through your opening is only low
percentage of this which would be possible with an clean airflow of an
streamliner - increase speed = increase of turbulences
Roadster (old fashion high boy) - they often use a air intake where original
was the radiator grill - if you use a intake which is in the "grill" surface,
you get again a problem with turbulences and vaccums in front of the air intake
- if you use a long "nose" out of the grill surface, app. 10 inches, you get
your air intake in cleaner air, which allowd you to use a smaller opening than
the opening directly on the grill surface. As the Coupe - increase of speed =
increase of turbulences
Hope this helps you, to understood the different necessary sizes of openings.
See ya
Pork Pie
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