Cowl Induction

[blk_ss02]

Can someone please explain how cowl induction works

[vetteemt]

On the SS hood air enters the hood via the scoop then is pushed into to cowl channels on the bottom side of the hood. These channels make a 180 deg. turn towards the front of the engine bay to the front of the air lid intake system. There are 4 or 5 holes where the air comes out of the hood and is sucked into the air intake.

[Firebirdjones]

Well the term cowl induction was derived from the rear facing scoops that were optional on the 69 camaros and the 70-72 SS chevelles.

They used pressurized air at the base of the windshield with a more subtle rear facing scoop.

What vetteemt explained is how the current systems work on the 4th gens if a functional hood is installed with a forward facing scoop.
Pontiac coined the term "ram air" in the 60's,,,,,with the idea being when the car is in motion the air is being forced into the hood. Over the years all 3 manufactures tried various forms of this with different style scoops and configurations. Some worked better than others but they all were trying to accomplish the same things.

[1MileCrash]

it's not so much that the air is pressurized so much as that the air rushing over the hood and the windshield creates low pressure zone at the cowl (the space between the hood and the windshield). so with low air pressure at that location if you open up slots that lead into the engine what will happen is that the pressure will try to equalize in the low pressure zone at the cowl. the attempt at equalization results in air being "sucked" into the low pressure zone from the higher (air rushing over hood and windshield) zone. pressure always moves from zones of high pressure to zones of low pressure.

it's actually more efficient than ram air due to the fact that ram air requires that some sort of a hole be present on the car in the direction of vehicle movement which results in a higher coefficient of drag. with cowl air induction there is no hole present in the direction of vehicle movement...rather the hole is present opposite that direction where there is already a hole or a gap. while this still has some coefficient of drag it is much smaller than having a hole facing towards the direction of vehicle movement (ie...air scoops).

[blk_ss02]

oh ok that makes sense thanks alot i know i have ram air, and i know what a cowl hood looks like but not how it worked, so thanks again

[SSTODD]

it's not so much that the air is pressurized so much as that the air rushing over the hood and the windshield creates low pressure zone at the cowl (the space between the hood and the windshield). so with low air pressure at that location if you open up slots that lead into the engine what will happen is that the pressure will try to equalize in the low pressure zone at the cowl. the attempt at equalization results in air being "sucked" into the low pressure zone from the higher (air rushing over hood and windshield) zone. pressure always moves from zones of high pressure to zones of low pressure.

it's actually more efficient than ram air due to the fact that ram air requires that some sort of a hole be present on the car in the direction of vehicle movement which results in a higher coefficient of drag. with cowl air induction there is no hole present in the direction of vehicle movement...rather the hole is present opposite that direction where there is already a hole or a gap. while this still has some coefficient of drag it is much smaller than having a hole facing towards the direction of vehicle movement (ie...air scoops).

This is the set-up on every nascar hood/engine for the past few years with 850hp motors, just without the raised hood.

[Firebirdjones]

Yep,,,and it works. Those nascar guys are always finessing the opening within the rules and finding HP.

This same nascar style was also used on a few 67-68 camaro's and even 66-67 chevelles over the counter.

Called the cowl plenum air intake, required no hood scoop at all. Anyone old enough to remember these?????

Buddy of mine has a 66 SS chevelle 375 hp car with this factory setup, dealer installed when he bought the car brand new. Still has it too with only 16,000 original miles on it.

I've played with the cowl induction setup on my chevelle, and found when I close it off the car looses a tick of MPH at the track.

I've also found the forward facing scoops work effectively as well on some models. My 70 Formula has a pair of forward facing scoops front and center, up by the front bumper,,,,,at high mph at the track, it would blow the little filter element for the crank case out of it's holder and rotate around to the rear of the air cleaner housing I had to wire tie that silly thing in there. I could run full boogy to 70-80 mph and it wouldn't move,,,,but once I took the car around 100 mph it would blow out,,,lol. Tells me there is some serious air being pushed into the air cleaner for sure. I've done things like remove the filter,,,,,block off the air scoops, remove the air cleaner all together and run an open element ,,,,,everything slows the car down about a tenth,,,,a very effective system with the scoops way up front.

Forward facing scoops that are more towards the center of the hood are not as effective though. But they do work,,,,,anyone ever try blocking off the fresh air on their 98-02 SS camaro's?????

I have. I tried putting a piece of tape accross the small openings under the hood right before it enters the air box. It blew the damn tape off,,,,,lol,,,,so I had to get drastic and stuff shop rags in there,,,,try it,,,,you may be surpised what you find.

[1MileCrash]

i'm actually having a 2" cowl hood put on my camaro. although it won't bring air into the engine it does have a slot that will extract hot air out of the engine bay...so it will have some functionality.