10-18-2009, 10:42 AM
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 #1 (permalink)
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Batman Junior
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Mythbusters "tests" efficiency of dimples vs. smooth, and clean vs. muddy car
Admin note: 2 threads were started on this topic. The other one is here: Mythbusters tests "golf ball" dimples
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I don't watch the show regularly, but this one might be worth tuning in for the entertainment factor.
Also.. don't they have it backward? Isn't the common myth that the clean car gets better mileage?
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10-18-2009, 11:50 AM
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#2 (permalink)
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Take me to your Earthling
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Quote:
Originally Posted by MetroMPG
Also.. don't they have it backward? Isn't the common myth that the clean car gets better mileage?
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Hmm, I can imagine having enough mud buildup in the wheelwells to reduce the distance between them and the wheels. Or mud sticking to the rear of the car, drying and hardening, layer on layer, in the shape of a Kammback extension. But by the time either of these would have a noticeable aero effect, the weight penalty would start to be a pain.
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10-18-2009, 02:53 PM
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#3 (permalink)
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Master EcoModder
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I will be watching it. I love mythbusters even tho they seem to be obsesed with explosions.
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10-18-2009, 03:50 PM
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#4 (permalink)
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Ecomod noob
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Quote:
Originally Posted by igo
I will be watching it. I love mythbusters even tho they seem to be obsesed with explosions.
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I love Mythbusters BECAUSE they seem to be obsesed with explosions... hehehee
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10-18-2009, 04:04 PM
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#5 (permalink)
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marcusmodder
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I think the muddy/clean thing is like the golfball dimple theory. Sometimes rough is better than smooth. I'm actually looking forward to this one...
If it works you could cover your car with rocker guard or ceiling texture and paint over it. Might look kind of cool.
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10-18-2009, 05:04 PM
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#6 (permalink)
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Master EcoModder
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They are supposed to be "dimpling" a car, I think.
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10-18-2009, 05:11 PM
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#7 (permalink)
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Master EcoModder
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Quote:
Originally Posted by MadisonMPG
They are supposed to be "dimpling" a car, I think.
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...so instead of " Body by Fisher" it'd be " Body by Top-Flite" (ha,ha)!
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10-18-2009, 05:32 PM
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#8 (permalink)
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marcusmodder
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I could just see them firing golf balls at a car to get the dimples.
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10-18-2009, 05:35 PM
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#9 (permalink)
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EcoModding Apprentice
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SOunds like a hail storm car to me! 
Dave |
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10-18-2009, 09:46 PM
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#10 (permalink)
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Left Lane Ecodriver
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I'm sure it'll be entertaining and worth watching.
I predict their conclusion will be "we can not detect a fuel economy difference between these two cars".
It would take a pretty extreme setup to do aerodynamic testing sensitive enough to detect mud. A wind tunnel would do it, but they wouldn't take a car to a wind tunnel for a simple myth like this. Short of that, you'd need high speed bidirectional coastdown testing on a totally windless day. Even if you accounted for airspeed, small crosswinds would skew your results beyond utility.
As to the effects of mud: It tends to increase the car's frontal area, obviously. Cakes of mud on streamlined surfaces will increase your Cd, while cakes of mud in your eddies will tend to decrease your Cd. A muddy truck with its panel gaps and hood cowl filled with mud will probably get better gas mileage, but unless your aeromodded Metro gets a teardrop-shaped tail made of mud, it's likely to get slightly worse gas mileage when muddy.
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