Some air filter figuring.

[cycleguy55]

I'm pleased to see the 9" x 2.5" and X-Stream combo is good for minimal loss on your 600 HP engine, as that's the combo I'm planning for mine and I'm nowhere close to that power level.

One aspect not covered in the calculator or your comments is that of airflow direction. Clearly an X-Stream top will allow airflow down into the carburetor in addition to the air flowing in through the sides of the 9" element. The 14" x 3" element, OTOH, passes air through the element and it then needs to flow horizontally before making a turn into the carburetor. I did see a post elsewhere that indicated Chevrolet L-88 drop bases are very good (Experience with Edelbrock air filter), but clearly different drop bases could have an affect on power depending upon how they are shaped and how good the airflow is into the carburetor.

None of this probably makes any difference when the engine is running even under a moderate load, but I could see how it might affect an engine running under WOT, particularly if the carburetor has a choke, as the space between the top plate of the 14" x 4" air cleaner and the choke horn could restrict the airflow.

All this is purely theoretical, and I'm curious as to whether anyone has studied or compared the above.