Turkey pan

[Gaz64]

Originally Posted by Unique427

Reprinted from a previous CC post:

The "Turkey Pan" (cold air box) was one of the reasons that the 427 performed like it did.
Doing the math helps us understand why. A hood scoop opening of 2"x10" or 20 sq. in.
moving through the air for one mile at 60 miles an hour takes in nearly 8,000 cubic feet of air.
Your 427 cu. in. engine, traveling the same speed, turning 2500 rpms is only using
350 cubic feet or so of air. When sealed against the hood with a rubber gasket
(which most folks don't like doing because the gasket chafes the paint) forms a high
pressure area between 2-5 psi of cold air pressure, depending on how fast you are moving.
The excess cold air spills out through the bottom opening, thus cooling the intake manifold
and the air charge running through it. It creates "free horsepower" and the only drawback
to this is that you must be moving!!

Not sure on who wrote this, but the maths is wrong.

20 square inches = .1388 square feet.

60 miles per hour = 1 mile per minute.

1 mile = 5280 feet.

5280 x .1388 = 732.8 cubic feet. PER MINUTE.

So where did 8000 cfm come from?

[patrickt]

Originally Posted by Gaz64

So where did 8000 cfm come from?

I asked Ellie to solve this math problem for you. She said that let's say he's revving at six grand with a WOT in first gear, and remembering that a cylinder only pulls in air every other rotation at 6,000 RPMs, it’ll pull in air 3000 times. 3000 times 427 equals 1,281,000 cubic inches per minute, which is the same as 741 cubic feet per minute. And since you're staying in first gear, you're spinning your tires hard and just barely moving, so the time to traverse the mile may be ten minutes or even longer. Ten times 741 CFM gets you pretty close to the 8,000 figure he quoted. Ellie's pretty smart, so that sounded good to me. She's gone to sleep now, so don't ask any questions.

[Robert66]

Don't forget the aerodynamic effect from the shape of the car and the hood. It certainly increase the value by a large number.