Bill my opinion is it will make a difference in the
height (where the carb is in relation to the hole...
is the carb still below the hole or is the carb in the
hole).... if the carb is below the hole and you can
mount a stub stack( my terminology I call it a "ideal
entry") so if you can put a ideal entry on the carb
and have the lip of it at the hole then the hole would
end up being the same size as the outer lip (just
smaller so you can seal it but not too small to effect
flow... if the carb is up into the scoop you need
to make it as big as necessary to get as much carb
up in there.... I think this is where the guys are
running into problems... not enough area above the
carb to get the air to make a smooth turn into the
carb... thats why I'm a firm believer in the ideal
entry to help (and you still need enough area above
the ideal entry... in this case(SCOOPS)... more is
better)...... IMO
Here some info from BG
There is no substitute for a well-designed fuel and air delivery system. By ignoring these two critical areas, all the work of building a strong powerplant is wasted.
Air Delivery
For maximum horsepower, the coolest, most dense air possible should be available at the carburetor inlet. Keeping restriction in the inlet path to a minimum - or better yet, pressurizing the air - is also desirable.
The denser the air, the more you can get into the cylinders. This allows the engine to burn more fuel and make more power. We recommend that a hood scoop or outside air intake should be installed wherever rules allow. Under hood air is heated by the engine and headers and reduces the amount of power that can be produced. A reduction in temperature of 10 degrees F. is approximately equal to a one percent power gain.
There should be a minimum of three inches of clearance between the top of the venturis and a hood scoop. If an air cleaner is installed, the tallest possible element is preferred with four-inch element preferred for racing engines over 500 HP.
When a hood scoop or external air intake is used, it is highly suggested that the carburetor be sealed to it. Otherwise, air will flow across the top of the carb and out of the inlet tract rather than into the air horn. If air is forced past the carburetor it can siphon fuel, causing the engine to run lean. Windshield snorkels are especially notorious for siphoning unless the rear is sealed. Air pan kits for sealing the carburetor to the scoop are available or they can be fabricated. An air bell or radiused intake should be used whenever possible to increase air flow into the carburetor.
It is not unusual for a drag race car to improve ETs by 0.3 second and increase top speed by as much as seven miles an hou after installation of a sealed scoop. A car will not pick up ET after the scoop is sealed off if the scoop is too short or the fuel delivery system is inadequate.
On oval track cars, the same is true. Paying attention to the inle tract design will pay off. Depending upon track length, oval track cars will typically improve lap times by 0.1 to 0.5 second once an optimized air intake system is installed.
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