Functional hoods?
03-10-2010, 12:36 PM
#1
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Thread Starter
Join Date: Nov 2007
Location: Montaner
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Functional hoods?
Do cowl hoods actually help cool your engine and if so by how much? Is a 2.5" effective or do you need a 3-4"?
Are there any other hoods that actually do something for the car other than look good?
Are there any other hoods that actually do something for the car other than look good?
03-10-2010, 03:01 PM
#2
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Location: Long Island, moving to arizona soon
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i just got a 4 inch but i didnt install it yet on the stang, but i did have a cowl on my bronco and it did keep it cooler under the hood a bit. i also had a cowl on my durango whiched seems a little better as well. i think each car is diff tho
03-10-2010, 09:57 PM
#5
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thats a tuff call really u would think forced air would be better. then you have a cowl which lets heat out from the back plus u got air from the grille to help flow it rigth out. so you got two diff ways to do it you would think only way to know for sure will be test
03-10-2010, 10:06 PM
#6
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but outta this i dont think 1 inch will make much of a diff the diff size is just for looks or to make more engine room
03-11-2010, 02:51 AM
#7
Join Date: Aug 2009
Location: California
Posts: 49
here is the technical way of looking at it.
Cowl induction has been used since the early days of Grand Prix racing in 1910. This method is a proven, if somewhat antiquated, way to make horsepower. Cowl induction hoods use a backward-facing scoop in the hood to draw in some of the cool, high-pressure air that collects on the windshield at speed. Though a properly engineered cowl-induction system looks good and works well, there are a number of options available on the market that don't carry many of this system's drawbacks.
Power Functions
As a car punches through the stagnant air at high speed, there are a number of areas that tend to accumulate high-pressure pockets. The front bumper, grille, headlights, windshield and wheel-well are the most common areas.
Since engines make more power with cool outside air than the hot ambient air found in the engine bay, it seems logical to tap these high-pressure pockets to feed air to the engine. In addition to lowering air temperature, increasing the air pressure around an intake artificially crams more air into the engine than the static air could, which is similar to how a supercharger functions.
Other Functions
Cowl induction hoods are used for a number of other reasons as well, prime amongst which are intake clearance and cooling. Since many performance intakes (particularly those found on carbeurated vehicles) are taller than stock, there may not be enough room under the hood to fit an air cleaner.
The second ancillary function of cowl hoods has to do with cooling. Though these hoods draw in cool air while at speed, when idling or cruising at low speed they go from intake to exhaust. Since performance cars tend to produce excess heat when idling, the ability to vent hot air from the engine bay may be the difference between a fun night out and a melted motor.
just a little article i found on cowls...so they do work.
03-11-2010, 05:59 AM
#8
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Location: western ma
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good article, legend. to add to that, here's some info on so-called "ram air" from wiki...
i.e. the vast majority of ram air hoods do little or nothing for performance. they do look cool though.
At higher road speeds, a properly designed hood scoop can increase the speed and pressure with which air enters the engine's intake, creating a resonance supercharging effect. Such effects are typically only felt at very high speeds, making ram air primarily useful for racing, not street performance.
Pontiac used the trade name Ram Air to describe its engines equipped with functional scoops. Despite the name, most of these systems only provided cool air, with little or no supercharging effect.
To be effective, a functional scoop must be located at a high-pressure area on the hood. For that reason, some functional scoops are located at the rear of the hood, near the vehicle's cowl, where the curvature of the windshield creates such a high-pressure zone, and may be placed so that their opening faces the windshield (a reversed scoop).
The scoop will be most effective if it is either mounted high enough to clear the boundary layer (the slow-moving air that clings to the surface of a moving object) or if it is a "NACA duct," mounted below the surface and designed to draw the faster moving air outside of the boundary layer into the duct. A shallow scoop that is not a NACA duct may not admit a useful amount of air even if it is open.
Pontiac used the trade name Ram Air to describe its engines equipped with functional scoops. Despite the name, most of these systems only provided cool air, with little or no supercharging effect.
To be effective, a functional scoop must be located at a high-pressure area on the hood. For that reason, some functional scoops are located at the rear of the hood, near the vehicle's cowl, where the curvature of the windshield creates such a high-pressure zone, and may be placed so that their opening faces the windshield (a reversed scoop).
The scoop will be most effective if it is either mounted high enough to clear the boundary layer (the slow-moving air that clings to the surface of a moving object) or if it is a "NACA duct," mounted below the surface and designed to draw the faster moving air outside of the boundary layer into the duct. A shallow scoop that is not a NACA duct may not admit a useful amount of air even if it is open.
