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Old 03-29-2010, 02:41 PM   #11 (permalink)
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thedarave
I totally saw that...And it worked...And they also proved that a hundred pounds or so of extra weight does absolutely nothing to the mpg...of a car of that weight and power..

So, the golfball effect works...it improved the mpg of the Taurus? car, by 15%? right, if I remember correctly.....totally spontaneously...and from what I remember, it was very very scientific and controlled..

But why oh why is it not being implemented? does it cost more to simply make dimples? or what?

I love that kind of educational program..



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Old 03-29-2010, 03:33 PM   #12 (permalink)
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Dimples on a car could work if you kept your car in a constant 180 degree spin like a golf ball something which I, for one, make every effort to avoid!
That's what I was thinking. Therefore, I asked if dimples would be good for racing disk covers, but I was told by smarter people than me that it wouldn't work.

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Old 03-29-2010, 04:03 PM   #13 (permalink)
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Yes, but I'm the one who actually saw it.. actually happen

here, I'm not going to rehash all this...

MYTHBUSTERS prove golf ball dimple theory on cars works!!!

the fact is, the golf ball effect, is not limited to balls..

what's all that's required
wind resistance, and solid object, air being acted upon by dimple surfaced object

turbulent flow, via dimpled object, was proven
laminar flow, is undimpled object, is proven
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Old 03-29-2010, 04:49 PM   #14 (permalink)
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I totally saw that...And it worked...And they also proved that a hundred pounds or so of extra weight does absolutely nothing to the mpg...of a car of that weight and power..
No. They only proved that 100 lb of extra weight has minimal effect on a car already in motion. They deliberately (and rightly, for the experiment) ignored the fuel used to accelerate the extra mass.
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Old 03-29-2010, 05:42 PM   #15 (permalink)
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golf ball

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Originally Posted by eqmos View Post
Yes, but I'm the one who actually saw it.. actually happen

here, I'm not going to rehash all this...

MYTHBUSTERS prove golf ball dimple theory on cars works!!!

the fact is, the golf ball effect, is not limited to balls..

what's all that's required
wind resistance, and solid object, air being acted upon by dimple surfaced object

turbulent flow, via dimpled object, was proven
laminar flow, is undimpled object, is proven
Remember,the golf ball is quite small in comparison to an automobile.Even coming of the tee in a good wood shot at 110-mph,without the dimples,the ball would have a laminar boundary layer and flow would separate before it got to the back side of the ball.
The dimples guarantee an early transition to a turbulent boundary layer,which moves the separation point back behind the ball,reducing it's wake and also the base pressure of the wake for lower drag and a longer drive on the fairway.
An automobile transitions to a turbulent boundary layer at about 20-mph do to it's size in relation to velocity ( the definition of Reynolds Number ).Adding extra roughness can only degrade performance.
I think Bicycle Bob has probably hit on what's going on,that the dimples are behaving like turbulators to feed kinetic energy into a boundary layer on the verge of stalling,allowing the flow to remain attached across a body section which wasn't properly proportioned.
Typically,turbulators cost a drag penalty all the time,but if they reduce form drag more than they aggravate skin friction,there can be a net drag reduction.Proper placement would require rigorous testing.
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Old 03-30-2010, 02:15 AM   #16 (permalink)
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Just a quick note,the belly pan on the new Ford GT is dimpled.
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Old 03-30-2010, 02:20 AM   #17 (permalink)
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Quote:
Originally Posted by eqmos View Post
I totally saw that...And it worked...And they also proved that a hundred pounds or so of extra weight does absolutely nothing to the mpg...of a car of that weight and power..

So, the golfball effect works...it improved the mpg of the Taurus? car, by 15%? right, if I remember correctly.....totally spontaneously...and from what I remember, it was very very scientific and controlled..

But why oh why is it not being implemented? does it cost more to simply make dimples? or what?

I love that kind of educational program..


That was an 11% improvement in mileage from the dimples.
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Old 03-30-2010, 02:28 AM   #18 (permalink)
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Just as a point of interest i have experimented a wee bit with dimpling on the intake manifold port surfaces on a carbureted V8 engine ,and found a reduction in emissions of about 10%.This was years ago and wasn't worth writing home about.But there was an effect.
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Old 03-30-2010, 02:49 AM   #19 (permalink)
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Zipp has done extensive wind tunnel research over the years. The fastest bicycle wheels on the planet are dimpled, does this advantage transfer to cars highway speeds? I was told years ago that a tennis ball will go faster with the fuzz on it than without it, seems like you want a "fuzzy" (or dimpled) surface for optimum drag reduction at speeds most of us encounter on the road.
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Old 03-30-2010, 04:35 AM   #20 (permalink)
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[QUOTE=Major Puffer;168373]Zipp has done extensive wind tunnel research over the years. The fastest bicycle wheels on the planet are dimpled, does this advantage transfer to cars highway speeds? I was told years ago that a tennis ball will go faster with the fuzz on it than without it, seems like you want a "fuzzy" (or dimpled) surface for optimum drag reduction at speeds most of us encounter on the road.[ /QUOTE] How about i take a tennis ball , flow test it on my cylinder head flow bench,then give it a shave and flow it again .Should give us an indication as to what is going on.

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