Aerodynamic Question
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From: Noblesville Indiana
Aerodynamic Question I was thinking today about about the front bumper on my formula. The front pockets allow no air to flow throught them so they act like big parachutes hindering aerodyanmic preformance. the link below shows the kind of bumper im talking about.
http://www.geocities.com/oifish2002/firebird.jpg (not my car just one I googled)
So I was thinking mabye I could drill some small holes at the back of those pockets to allow some more air to reach the radiator and engine?
Does this sound like a good idea or should I just leave it be?
I posted this same question in the General Maintenance & Repairs but I thought that this might be a more appropriate place.
http://www.geocities.com/oifish2002/firebird.jpg (not my car just one I googled)
So I was thinking mabye I could drill some small holes at the back of those pockets to allow some more air to reach the radiator and engine?
Does this sound like a good idea or should I just leave it be?
I posted this same question in the General Maintenance & Repairs but I thought that this might be a more appropriate place.
Technically, holes would probably increase drag (though they could potentially increase cooling/breathing). You'd really have to run it through a wind tunnel to find out, but I imagine once there is sufficient backpressure built up in those pockets very little air resistance is added due to them. Drilling holes in the back of them would eliminate any pressure buildup, letting potentially turbulent airflow into the engine bay. Again, this is just speculation, and actual testing could reveal any truth to this.
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Air won't compress at road vehicle speeds much at all. Once the pocket fills up, it behaves as a solid, flush surface to further incoming air, routing it around just as if it were smoothly filled in.
2002BlackSS is correct that opening up the back will increase drag. Because you are providing a drain for that air, the drag is continuous, since it never fills up and stays static. Also, when the air eminates out of a small hole, it will indeed create turbulent flow. This will almost certianly interfere with the existing flow already under the car. It could not only increase drag, but reduce airflow across the radiator and into the intake. It wouldn't be a huge difference, but, do ya really want any?
To further reduce drag, the best thing to do is put a clear flush mounted cover over the pockets.
I know I just said that they behave that way once filled up, and they do, but there is a catch/limit. Any time the air changes direction (bumps, dips, turns, wind, etc), the pocket can spill over and empty out a little (sort of behaving as though it had an opening in the back of it). It then has to fill back up, and that's more drag.
If you put a hard cover over it to keep air out altogether, you prevent that and get the benefits all the time.
2002BlackSS is correct that opening up the back will increase drag. Because you are providing a drain for that air, the drag is continuous, since it never fills up and stays static. Also, when the air eminates out of a small hole, it will indeed create turbulent flow. This will almost certianly interfere with the existing flow already under the car. It could not only increase drag, but reduce airflow across the radiator and into the intake. It wouldn't be a huge difference, but, do ya really want any?
To further reduce drag, the best thing to do is put a clear flush mounted cover over the pockets.
I know I just said that they behave that way once filled up, and they do, but there is a catch/limit. Any time the air changes direction (bumps, dips, turns, wind, etc), the pocket can spill over and empty out a little (sort of behaving as though it had an opening in the back of it). It then has to fill back up, and that's more drag.
If you put a hard cover over it to keep air out altogether, you prevent that and get the benefits all the time.
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Aerodynamics are a moot point until you're doing 100+mph. Below that, there is really no effect from air at all that you could change and feel a difference.
Wanna decrease drag on your car? Draft someone over 80mph...that's about it.
Wanna decrease drag on your car? Draft someone over 80mph...that's about it.
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Interesting, I never would have thought of the pockets "filling up with air" I guess Ill just leave them alone and not mess anything up.
Thanks all for the replies
Thanks all for the replies
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Originally Posted by Toasty
Aerodynamics are a moot point until you're doing 100+mph. Below that, there is really no effect from air at all that you could change and feel a difference.
Wanna decrease drag on your car? Draft someone over 80mph...that's about it.
Wanna decrease drag on your car? Draft someone over 80mph...that's about it.
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Originally Posted by oifish
Interesting, I never would have thought of the pockets "filling up with air" I guess Ill just leave them alone and not mess anything up.
Thanks all for the replies
Thanks all for the replies
You could stick lights in there. I've see a few of that era with rectangular driving lights in there, they look kinda cool. Or, the only other option is to make brake ducts or some such out of them, but unless you're into ORR, you won't really see any benefit, and that's a lot of work to do for no benefit.
Originally Posted by Tavarez
Has anyone ever ducted stuff to the intake from the front? Would it work to duct air to the intake... the distance seems like it would be too far to actually be effective.. but the brake ducts might work.
Those are great for brake ducting. You cut through the foam support and then cut holes throught the "bumper". You then direct the air straight into the frame rails. You cut some holes on the inside of the frame, add some spray-on foam to force the air to flow out and into a flex vent and then the flex vent is directed into the brake rotor hub. Some racers do this, works really well.
Last edited by JasonWW; May 27, 2006 at 06:32 PM.
