wondering if a cowl hood would allow more air to travel up in front of the air dam if the air that was already in the engine bay had a place to go then it would allow a greater amount of cool air to be swept up by the dam. just a hypothesis tell me what you think.

 

i was kind of wondering the same thing. i've got a cowl hood and was thinking of adding a piece of yarn to see what direction the air was traveling.i remember an old carcraft where a guy removed the rubber seal and spaced the back of his hood up to make it run cooler. they called it an old racers trick.i don't know if it would leave out the top or bottom. it has to go somewhere

 

I believe the air flows into the engine bay thru the cowl but i would like to here you're yarn test results! to be sure

 

It might help, but not as an air outlet. I make these observations based on an ASCD Ram Air hood, which has about a 2 inch cowl at it's rear edge. I also use Rain-X, so rain drops slide around my windshield like they were ball bearings.

The air coming over the hood will hit the base of the windshield, which is pretty steep on a thirdgen, and create a small area of high pressure. This pressure causes rain drops to slide up the glass, or out to the sides.

With the cowl hood, the air moving over the top of the hood produces a low pressure area just behind and below the edge of the cowl. The air continues along and strikes the windshield, as before, but higher up. This means that a little of the high pressure created by the windshield goes down, towards the windsheild wipers.
Air wants to move from a high pressure area to a low presssure one, so the cowl hood will actually pull air in to the engine compartment.

If you want to modify the hood to pull air through the engine compartment from the bottom, use louvers. Of course, louvers don't look as tough as a cowl induction setup.

 

Air flows into the engine bay through the cowl induction. Put cold air flowing into the engine bay never hurt anything either.

 

If you have a cowl hood watch as you drive sometimes debris will slip up the hood and invariably go right to the cowl inlet. it is a good inlet but air will not exit so it is not a good exhaust for hot air. I have a Harwood 2" cowl hood on my Z man does it look wicked as if Chevy should have built it that way, but in no way does it help with anything but looks.

 

Around town, it's an air outlet. Mine runs cooler around town without the seal--you can feel the hot air blow out. You have to get going pretty fast for the air to start entering the cowl induction--it has to overcome the air from the fan and forced air from the air deflector. If your air deflector 'grabs' enough air it won't ever enter the cowl.

 

Right, when you're sitting still you can see the hot air come out of the cowl opening.

What surprised me though is that at 60 mph or more on the highway, my car is running quite a bit hotter since I put the 2 1/2" cowl hood on, I'm pretty sure it has to do with the fact that all the air from the cowl is meeting the air coming in from the front of the car, kind of canceling each other out and not flowing through the radiater as much as it should. My car never got hot before the hood.

On another note, this thing sucks in a tremendous amount of air, when I wash the car the water rolls over the cowl and gets sucked into the engine compartment, They'ed definately pull in all the air you needed if you had an open element filter.

 

Interesting considering when I leave my driveway at speeds greater than an idle or 20 and up I get any leaves and other debris collected on the cowl panel to suck up to the hood cowl inlet. This happens all the time under all conditions water does the same when I leave the car wash or it rains. believe me it's still an inlet.

 

I have an ascd 2" cowl on my car. Before the hood change, you couldn't put your hand on the TPI intake plenum. but afterwards after the car has been moving to get air to come down into the hood, the TPI plenum is one of the coldest objects on the car. I think at least a drop of 40-50 degrees, and some horsepower to boot. a cowl is worth it.

i really dont think that the cowl going into the engine bay would mess around with the radiator because there is a huge high pressure area infront of the radator that pushes air through as well.

 

Right, there's already a huge high pressure area in front of the radiator pushing air through it, now add another one coming through the cowl and meeting that one(going the opposite way) and it has to at least slow the air down, right.

Not a big problem just a few degrees warmer at higher speeds.

 

i've finally got a day off and its not supposed to rain. i'm going to do my yarn test and i'll post the results- if the yarn sticks.sounds like there are allot of different results

 

i tried the yarn thing today or yawn thing. i taped6 inch pieces of yarn at the top and base of my 2"cowl. i added pieces from the base of the windshield and at 4 and 6" from the base. i was suprised to see as soon as i took off the cowl pieces and the ones at the base of the windshield flowed into the scoop. the ones at4" kind of went back and forth. the dual fans didn't make a difference.i'm glad i used duct tape , it looked like allot of air was going in. next question, does it all go out the bottom? i guess that would be a low pressure area, any engineers out there?

 

well, if its going in the back AND front, and the bottom is the only other outlet....

 

Use Louvers on the sides of the cowl to help with this, if you can get them at an angle from the cowl its best as you don't end up sucking up warm air expelled from the engine bay back into the cowl defeating its purpose. If you really want to get this going you can create a plastic or sheet metal dam under the engine bay (Plastic is more expensive but doesn't sound like you have the cymbal's from an entire band under your car while driving) And last but certainly not least would be to consider venting some of that hot air into your wheel wells (Specifically directed at the backside of your brakes as they are MUCH hotter than the air exiting the engine bay)
A note on brake cooling, hot air is better than cold air for a number if reasons (I know you initially think colder is better because a larger temperature difference cools faster) First the brakes have to be warm to work best, just like your engine. Secondly brakes get REALLY HOT when you use them so with warm/hot air there is still a massive temperature difference to cool them. Third the brake rotors stay warm and usable with the expelled engine bay heat. Fourth, when cold air is blown or really hot brake rotors they have this annoying little tendency to EXPLODE!!!

Just a little food for thought...

 

The only way a rotor would explode is if you had really really cold air going straight onto a rotor that is glowing orange/red... and even then it is unlikely. The only time something like this would happen is under extreme circumstances which most of us will never be in.

Extreme circumstance:

 

Sure bud, I can think of more than one production cars that have this problem. How about a skyline gtr 32, they blow up all the time because of the brake vent system.
Research and you will find I have done mine

 

guess that's why they call it " cowl induction"....
just a guess