Turkey pan

[SBSerpent]

What is the purpose of it and why is it only implemented on BBs?

[Unique427]

Originally Posted by SBSerpent

What is the purpose of it and why is it only implemented on BBs?

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!!

[patrickt]

Originally Posted by SBSerpent

What is the purpose of it and why is it only implemented on BBs?

The biggest advantage of the TP on today's street driven big block cars is that it helps prevent gas percolation in your carb. Today's gasoline is crappy compared to the Sunoco 260 we had as kids.

[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.

[tonywyso]

Heat deflection and they look cool.

[SBSerpent]

The numbers only matter if the air is 'theoretically' going directly into the carburetor. BUT, from the photos that I have seen, how is the TP directly sealed to the hood scoop? Sure, I do see a rubber gasket around the perimeter of the TP but for me I can't see how that forms a pure cold air induction seal thru the hood scoop.

Regardless, still looks cool!

[Gaz64]

A turkey pan's function is two fold, one is to act as a heatshield from all the sources around the carburetor, the second allows the carb to be fed with outside cooler air.
With a 427 at 2500 rpm cruising, we might be using about 1/2 of 300cfm (1/2 atmosphere, 15 in Hg manifold vac), so 150 cfm. That little tiny opening will not be supplying 8000cfm at 60 mph cruising. We need 1.5 square feet of scoop inlet area to supply 8000cfm in one mile per minute.

That's a duct opening of 36 x 6. That's a big scoop.

You might get a "supercharge" pressure in the airbox with a scoop of this size.

[xb-60]

Patrick, what's Ellie's comeback on Gary's maths?

[hauss]

What about the humidity? Will it take up more space creating more hp.