Thanks for the link, but there's no reference to Jenkins using a scoop open at both ends.

How to design the scoop?
1. sealed to the carburetor or base plate (foam gasket is enough).
2. intake opening is in clean air (or the best you can get), generally way above the hood line but will vary greatly (also front to rear on the hood) based on not only the shape of the nose, but the terminal speed - air tends to go above the roof as speed goes up.
3. for big engines with high trap speed it's a puzzle: it needs a 12" hole for the 60 foot (where car speed does nothing for air intake), but only a mail slot at 200 mph, there are formulas for this at SCTA/BNI. A 100 mph car only needs a small scoop for 60 foot (but still position-critical), and even this can be smaller for top speed.
4. cross-sectional area inside the scoop behind the opening should greatly expand (10 times: 3" × 3" becomes 10" × 10") to convert the incoming air velocity to positive pressure.
5. the scoop internal volume should be really big, trying to completely stall air speed and make it passive, so it only "sees" vacuum toward the boosters.
6. some of the benefit will be intake temp reduction, don't know how to separate the 2 effects without instruments and computer.