E46Fanatics - View Single Post - The HPF Hood Was Born
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Old 11-09-2012, 01:30 PM   #59
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Join Date: Oct 2006
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Originally Posted by FragNasty View Post
I think it would be cool to have a hood designed with a discrete ram air duct positioned just over each headlamp.

Imagine a 1/2" to 1" gap between the top inside edge of the headlamp and the top inside edge of the hood that covers the lamp on each side of the grill. This opening would be triangular in shape where the most acute angle would be formed by the intersection between the top outside edge of the headlamp and the top outside edge of the hood.

The lines of the hood over the lamp will have that aggressive "over-hang" look. The air would flow over the headlamp, into this triangular opening (the "overhang") and pass through the air passage ducting directly to the air filter.

Of course the central portion of the hood would need to be reshaped keep the same relative proportions of the OEM hood and help make such a design work.

The ducting could be held in place by the same snap ins and tabs that another member suggested be used to hold the shutters in place. People without the turbo kit could flip the ducting over so that air could feed an after market airbox on the drivers side (another option for the NA guys).

I hope my description was clear enough.
Letting air under the hood at the front edge would cause a lot of buffeting and shaking at speed. For this reason BMW uses rubber seals to seal off air from entering hear. Also, you would have to make that air do a sharp 90 degree turn, and then a full 180 degree turn because air travels upwards through the airbox so air needs to enter from below. You're probably going to lose all possible benefits right there.

Also, you aren't going to be able to force air into the airbox from a vent in the hood by reversing the ducts. Just the air traveling over the opening will want to extract some air, and if the vents are in the front third of the hood, just the shape of the car will extract air from the vents. I wouldn't be surprised if the E92 M3 has the hole into the airbox in the hood just for letting out intake sound.

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