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Old 10-16-2009, 07:13 PM   #1
Bus Nut
sportyrick's Avatar
Join Date: May 2006
Location: mid Mo.
Posts: 916
Year: 1976
Coachwork: bluebird
Chassis: F33695
Engine: 427 chevy converted to 466
Rated Cap: 84
air dam

After reading a post years ago about air drag, air dams and their efficiency I decided to try it out on my bus. Now if I remember the story correctly 60% of your drag is from underneath your vehicle and it squares itself every 10 MPH. Knowing someone who has a ZO6 Corvette and studying it on a lift the GM boys understood this very well, that car is flatter on the underneath then the road it drives on. If you ever get the chance take a peak underneath a ZO6 or an F1 car you will be amazed how flat they are. Thinking about this for years I was always on the hunt for something cheap that would fill the bill for my test of this theory. Having previously worked for a research university and while there on business I was nosing around their test facilities and spied just what I needed, something flexible, flat and black. I acquired some space age carbon fiber that had been through some extensive testing for ultimate tensile strength. This stuff is not your normal carbon fiber which is really stiff like fiberglass, aluminum or steel but is really flexible like plastic or Lexan and is tough as anything you'll see. You can practically tie it up in a knot and then untie it again and it shows no strain, if fact I rolled it up into a tube to bring it home. Plus if you have never worked with Carbon Fiber you have never experienced the cursed fibers, they are something like catfish fins, really stiff and prickly and love to get into your skin and make you bleed. This is none of that. Super flexible, super strong and not too bad for the eyes either. I cut it into the shape I thought would work then built a framework to hold it in place, a pretty strong one too, 1 1/2" pipe and 2x1/4" flat stock hinged on bolts so if I did hit something it would swing back out of the way and then I would only have to kick or hammer the mount back to verticle. I tested it that week by backing into a 7-11 so my kids could get some beer and drug it backward over a hump in the parking lot. There was a little rub on the right corner but otherwise it was just as it was. Then we went down a mile long tractor lane across a farm and drug it some more and it only got muddy. IT SURVIVED the worst and lived to tell about it. How was the gas savings you ask, well unfortunately I changed the carburetor recently so I can't swear about my fuel savings just because of the air dam but overall I picked up .7 MPG, so far. Now that's .7 added to 5 MPG so it's a significant savings, about 17% if I worked that danged calculator right. Was it worth it, you bet. I think my top speed was a little better and the engine was working a little easier. I will have more proof as I drive it longer but it definitely did help. oh ya, it's 2mm thick, 11' long, 10" lower than my bumper and is 8" above the ground and if you wanted to do this I would suggest teflon or polyethylene sheet, mud flaps or something that is stiff to resist wind yet flexible enough to bend when pressured. sportyrick
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Old 10-16-2009, 09:49 PM   #2
Bus Nut
Join Date: Aug 2007
Posts: 758
Re: air dam

That looks real good Rick.
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Old 10-19-2009, 12:21 PM   #3
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Papabear's Avatar
Join Date: Dec 2008
Location: Southwest Wyoming
Posts: 334
Year: 1991
Coachwork: ward
Chassis: IH
Engine: dt466
Rated Cap: 72
Re: air dam

A-1 on looks. good job.
"I've never been lost, but I been mighty confused for several days"
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Old 10-19-2009, 03:20 PM   #4
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Join Date: Nov 2003
Location: Twin Falls, Idaho
Posts: 809
Very nice look and good work

My Crown is already pretty near the road way, but maybe my Blue Bird would be a candidate. Do ya have any substructure and construction pics? Teflon sheets here are very expensive. Good information for me. thanks, Frank
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