Aero experts - will perforated aero panels work?

[brucepick]

My air dam extension is a work in progress. Currently has the curved front panel and an undertray that extends to the OEM belly pan.

Next step is to wrap a curve around the corner smoothly. Unfortunately this will enclose the additional pair of horns I mounted there this past winter. You can see the galvanized screw head on the oem air dam; the horns are behind there and do project sound well.

How about a perforated panel for the flat straight part of the air dam's side portion, to let the horn sound out? Will it behave aerodynamically nearly the same as a solid flat panel? I could remount the horns outside the new enclosed air dam but then they will be out in the air stream; the losses from a perforated panel might be less than those from horns protruding?

[brucepick]

I'm planning on enclosing the chamber. Not a total seal but I think I can make an enclosure with more plywood + brackets etc., fitting up to existing body components.

So if I use perforated panels on the sides I don't think there will be a rush of air coming from behind.

[MetroMPG]

I don't think perforations are going to be a huge problem, as long as the holes are small.

[basjoos]

Line the perforated panel with a windproof lightweight fabric like ripstop nylon that will let the sound through while stopping the wind.

[JanGeo]

Aim the air horn towards the ground and the sound will bounce off of the ground and be heard.
The front air dam has to channel the air to the sides and should have a curve to it to make the air go to the sides and not under it or else you loose the benifit.

[brucepick]

Originally Posted by JanGeo

Aim the air horn towards the ground and the sound will bounce off of the ground and be heard.
The front air dam has to channel the air to the sides and should have a curve to it to make the air go to the sides and not under it or else you loose the benifit.

Yes. The added air dam has the same curve as the oem air dam; however it's not a strong curve so doesn't show up well in the photo. That said, I'm considering building up thickness towards the center part for a more radical curve. And maybe some kind of projection at bottom of the extension to keep some air from scooting below the air dam.

As for aiming the horns at the ground, that's the current setup but the undertray is in the way. If I mount them below the undertray they'll be in the air stream.

Actually this is probably an issue for anyone doing aero mods if you want effective horns. Between grill blocking and total-wrap air dams and side skirts there aren't tooo many places where horns will work well. Thus my interest in a perforated side panel.

[Bill in Houston]

Originally Posted by basjoos

Line the perforated panel with a windproof lightweight fabric like ripstop nylon that will let the sound through while stopping the wind.

I like this idea a lot. Good one.

[Bman83GL]

What if you used louvers instead of holes? If you directed the openings away from the air stream then air would pass right over it, but you would still have an "opening" for the pressure wave. You can find plastic louvers of all shapes and sizes in wheel wells and the like in salvage yards.

[brucepick]

FWIW, I built the side panels from two solid pieces of flexible plastic. Eventually I might move the horn to a better location low in the wheel arch but for now it's OK.