I have decided to go ahead and make a ram-air box for my cowl hood. I plan on making the box inclose the open element air filter I already have. I will then make it seal to the hood where the cowl hole is. Then I will run two cold air induction hoses to the front of the car.

I have two questions:

1. How can I get the angle of the hood? It is a stock cowl induction hood for a 72 chevelle. The box will have to be lower in the front than it is in the back. Any previous attempts at this?

2. For the cold air induction that I plan on running to the front. Can I use a dryer vent tube? It is flexible, lightweight, and cheap. The only problems would be with the ribs. Will these slow air flow? Are they too big or too small?

Any help on this would be great. And if any of you have some pics or examples, that would be great. Thank you all.

Posted this to give you some ideas, I'm not sure if this will work on a Chevelle but I like this setup better than hoses. You'll need to see how much room there is between the radiator support and hood. The Nova's have plenty of room to duct air through there.

http://www.iola.com/71nova/images/airbox02.jpg

Thanks for the picture, but I forgot to state that this is a factory cowl induction hood. My current air cleaner is 14" in diameter. I am thinking of making a circular air box about 19" in diameter that matches the center of the hole in the hood. I will then run two air duct lines to the front of the car. That way it will use the stock cowl induction plus to cold air lines running to the front.

As far as the duct work, I was going to use two 4" dryer vents, but since I have an aluminum intake the box is much shorter and will only compensate for two 2 1/2" dryer vents. Will be enought air flow? Too much?

Lost yet? If not, let me know what you think of my idea. And anymore pictures would be great. I like to see different ideas.

Anyone?

I have a 70 SS and understand what you are contemplating. Here is the question, how are you going to connect the dryer tubes to the underneath of the 19" circular plate? I would think that the carb linkages and other hardware would be in the way? Good idea, let us know how it works if you attempt it.

Tino

Why don't you just use the opening of the cowl hood to get the extra air in? :confused:

I played around with a ram air setup on my 68 Camaro and learned a couple things in the process.

First, how the air flows into the carb is important. If the flow is very tubulent and cuts across the top of the carb it will mess with your vent and pressurize the float bowls. My first attempt really fell on its face at high speed (too turbulent). If you ever suspect this is the problem, tie the two float bowl vents together with a piece of surgical tubing and a tee, then run a line from the tee to a non-pressurized area in the engine compartment.

I think you already said you were using an air filter, but its really important that you do use one. It helps smooth air flow out and provides a steady signal.

4" aluminum air dryer duct works fine. The ribs don't hurt anything at all. You can also get all kinds of round flexible ducting made of different materials (that looks better) at McMaster-car.

I think two 2-1/2" ducts would be too small -- its not like exhaust, you are sucking air in rather than pushing air out. A single 4" has a 12.5 square inch cross-section and two 2.5" ducts together are only 9.8 square inches.

Did you look into premade units by Ram Air Box Co.
{www.ramairbox.com}

Thanks for all of the replys. The problem with the premade boxes is there is no opening in the top for the cowl induction. It is hard to explain, and I don't know if I can turn my AutoCAD drawing into a file you guys can open up. If I can then I will post the blueprints I came up with.

The reason for the 2.5" tubing is because the inner air cleaner has a diameter of 14" and the air box will have a diameter of 19". Which is an extra 2.5" on each side. Since the tubing is 2.5", this is no good. So to create more surface area on this sides I will have to angle it up from the base of the air cleaner to the cowl hole in the hood.

_______COWL________
\ /
x\ [---------] /x
\[ ]/
-----------
lllll
lllll

I hope the drawing turns out. The brackets in the above drawing is the current 14" air cleaner. The l's is the carb. The box surrounding the air cleaner is the air box. BTW, this drawing is not to scale. The line across the top is the hood and where the COWL is is where the hood opens up to the cowl induction. The air box will seal agains the hood of the car. The x's represent where the two 2.5" air ducts will connect to the box.

I hope someone can make some sense of this. Let me know what you think. Fabricating this will be no problem, getting it to work will be the problem. Anymore suggestions? Keep them coming.

I guess you can see that the picture did not come out.

._______COWL________
....\................... /
....x\.[---------] /x
.......\[---------]/
........-----------
.............lllll
.............lllll

I think I got the spacing right, just ignore the periods. I will copy my last post so it is easier to read.

I hope the drawing turns out. The brackets in the above drawing is the current 14" air cleaner. The l's is the carb. The box surrounding the air cleaner is the air box. BTW, this drawing is not to scale. The line across the top is the hood and where the COWL is is where the hood opens up to the cowl induction. The air box will seal agains the hood of the car. The x's represent where the two 2.5" air ducts will connect to the box.

I hope someone can make some sense of this. Let me know what you think. Fabricating this will be no problem, getting it to work will be the problem. Anymore suggestions? Keep them coming.

Have you seen the stuff these folks sell? Take a look right here (http://www.ramairbox.com) .

How is everything turning out? I hope you accomplish your invention. I've also been toying with the idea of making some sort of "cold air induction" for my '71, but haven't been able to actually purchase and make anything yet. I unfortunatly have the stock flat hood and limited space. I'd really benefit from some more cold outside air. I do plan on buying a nice lil 4" cowl induction, and still plan on toying with some sort of colr air with the hood. I figure, if a bigger hood will help get some more cold air in, why not help it out some? Good luck and PLEASE let me know what turns out!!!

Ram Air Box CO. has a reverse unit that will draw air from the firewall. All you would have to do is open the top to mate to the hood, this may not be what you are looking for though, I am unclear as to how you want this to work.

It seams to me that you are going to defeat the purpose of a Ram Air system and the Cowl induction system by connecting the two. The Cowl Induction allows cooler air off the high pressure area of the back of the hood/winshield area. From what you read, they found out years prior to the Cowl hoods that at high speeds, the old style low scoops would acutally flow less air. Ducted ram air systems allow for cooler intake air then is available from under the hood. The true ram air effect of 1 - 2 PSI positive pressure doesn't happen until high speeds - 60 - 70 MPH + depending on the pressure build at the nose of the car which is very dependent on the aerodynamics of the car itself. Either way, you are defeating the purpose by having these connected. You can only get an effective pressure build at the carb if the housing is sealed. So in effect, if you run ducted ram air, the cowl inlet should be closed anyway. You are not really accomplishing anything by running 2 openings.

If you're wanting to get a better ET / MPH out of it when racing I think you'll have better luck pulling the air from the front of the car than cowl induction. It's not really visible in my photo above, but the back of the cowl scoop is blocked off - all the air comes from the front.

How much did it cost you to make that Nova?

More than I had in mind when I started LOL... isn't that the way it always goes?