Aerodynamics & Diverting Wind Resistance ?

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Another thought, either lose the front bumper, and run nerf bars, or maybe consider running a back bumper off a 1st gen Camaro or Firebird as a front bumper. Either one would allow a custom front valance. Another option would be to cut the bottom portion of the front bumper off. Save some weight off the front.
Believe this or not, I've actually looked and thought to cut the "bottom" portion of the front bumper off for weight loss - at the farthest point forward. But I also wonder if the 'rounded" bumper helps with wind resistance for the underneath. Is it directing air flow ???
 
And at what "speed" or MPH before it matters ??
And even then, how MUCH does it matter ???

Definitely anything over 100 MPH, and quite a bit. I need to adjust my ET when the wind flags show a headwind.
 
And at what "speed" or MPH before it matters ??
And even then, how MUCH does it matter ???


Definitely anything over 100 MPH, and quite a bit. I need to adjust my ET when the wind flags show a headwind.
precisely... head wind or tail wind moves the ET. It also moves the gas mileage when traveling across the Interstate, especially in a truck or van. And that might be at 65 MPH.
 
Just so you know from my experience. I had a 89 D200 with a 360. Money got tight for me driving 500 miles a week with $4.00 a gallon gas. I made a perimeter frame out of 2x4’s flush inside the box and covered it with 1/4” plywood. I went from 16 mpg to 17mpg. I rattle canned it flat black and even made it pivot at the back of the cab to lift up for easy access. I wonder if I could have picked up a little more with a smooth paint finish like a coat of ploy urethane.
 
Just so you know from my experience. I had a 89 D200 with a 360. Money got tight for me driving 500 miles a week with $4.00 a gallon gas. I made a perimeter frame out of 2x4’s flush inside the box and covered it with 1/4” plywood. I went from 16 mpg to 17mpg. I rattle canned it flat black and even made it pivot at the back of the cab to lift up for easy access. I wonder if I could have picked up a little more with a smooth paint finish like a coat of ploy urethane.
Nice! I don't know if they are still available, but I was thinking of the old "snap on vinyl" coverings they used to sell for the trucks.....
 
While that does not sound like much, I picked up another 29 miles pretty much for the week. Any thing helps when it takes $88.00 to fill a 22 gallon gas tank.
 
Like I said I was tight on Money and I used materials that I had laying around. I even had the rattle can on my paint shelf. Matter of fact it was dead after one coat.
 
A few old boys around here claim they gain fuel mileage when their fishing boat is fixed to the top of their truck.
 
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An upholstery shop should be able to make one...
I'm thinking one of those old 70s - 80's aluminum topper. Very cheap, light, and would prove the point one way or the other. If it weighed 60 lbs and I still dropped a 1/2 tenth, then... Put it on with C-clamps, make a pass, remove it, make another pass. Should be a tale-tale
 
I'm thinking one of those old 70s - 80's aluminum topper. Very cheap, light, and would prove the point one way or the other. If it weighed 60 lbs and I still dropped a 1/2 tenth, then... Put it on with C-clamps, make a pass, remove it, make another pass. Should be a tale-tale
However wide your bed is 5 and 1/2 ft or so?.. get two of those by 4 ft and they could lay down in the back of the bed and then put them on and turn them sideways..
Speaking of sideways....lol...
Wouldn't the torque of a stroker kit push you through all this trouble? LOL....
 
However wide your bed is 5 and 1/2 ft or so?.. get two of those by 4 ft and they could lay down in the back of the bed and then put them on and turn them sideways..
Speaking of sideways....lol...
Wouldn't the torque of a stroker kit push you through all this trouble? LOL....
It has a stroker. I have a 318 with a 3.58 stroke and I was able to go .090 over on this one! :)
 
I'm thinking one of those old 70s - 80's aluminum topper. Very cheap, light, and would prove the point one way or the other. If it weighed 60 lbs and I still dropped a 1/2 tenth, then... Put it on with C-clamps, make a pass, remove it, make another pass. Should be a tale-tale

The Farm Truck has a topper, I always thought it was to hide the roll bar. Maybe it is for aero?
 
Do you see many hollow airplanes?...
Just a few...just bustin' your chops.
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I'm thinking one of those old 70s - 80's aluminum topper. Very cheap, light, and would prove the point one way or the other. If it weighed 60 lbs and I still dropped a 1/2 tenth, then... Put it on with C-clamps, make a pass, remove it, make another pass. Should be a tale-tale

"Farm Truck" ... is fast .. lol
 
I'm at work and don't have time to read 4 pages right now in case anybody else mentioned it, but there is a website called ecomodders.com that offers a lot of info on fuel mileage gains. Not just in modifications-as the name would suggest, but also driving tips, etc. Some of it way out there, but regardless, a lot of aerodynamic mods done to the rear of the vehicle to reduce the suction effect of a blunt ***-end. Thats why you see those flaps on the back of semi-trailers to help steer the wind to blend back together.
Thats why the Daytona and Superbird also got the back window treatment along with the pointy nose.
 
MPH is a huge factor in aerodynamics. One easy example is the Dodge Daytona. The body was designed to be clean up to road speeds of about 100 MPH. Anything under that speed and the car was clean and relatively stable. From 100 to 150 MPH, the car was a bit twitchy, but a decent sized wicker bill on the spoiler would make the car tolerable.

What happened after 150 should be a textbook lesson in aerodynamics. The body at speeds about 150 MPH started to generate lift. The air pressure under the car was greater than the air pressure over the car and the car would literally try to stand up. It was actually borderline unsafe.

The “cure” was a bigger, more effective rear spoiler with a relatively large wicker bill and a bigger spoiler up front to keep the air from going under the car.

The problem with those modifications is they take a bunch of power. Using a bigger spoiler and wicker bill causes more drag, and more drag takes more power. So that particular car was at a huge disadvantage as a Pro Stock car. In know, for a fact that Alderman hated those cars. You couldn’t win with them unless you wanted to drive a car that was loose over 150 MPH. Pretty easy to go full turtle when the car is unstable at those speeds.

The upshot to all this is this. What looks good at one air speed may not be good at another air speed. To the point the car can become unsafe.

Obviously you are not talking about speeds that high but the principle stands on its own. Unless you have some way to quantify any change you make you have no idea what the end result will be at various MPH.

If you can use CFD that would be a good start. Air flow can be quite counterintuitive. A change that looks good at 100 MPH may be a death trap at 150.
 
I thought the winged cars were docile at 150+? I read one report that " at 150 the wind noise went away and the car settled in nicely..." one was faster than the other, had to do with the chin spoiler and rear window shape. Myth busters did a test on open or closed tailgate for mileage, they both ran out of of gas (80-85 miles) within 5% of each other, the tailgate UP won! They said the pressure buildup in the open bed of the closed tailgate made the wind go over the truck smoother. the open tailgate didnt have the same high pressure bubble and the back of the cab acted like a parachute with a low pressure area. I see semi trucks with tail cones now.
 
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I thought the winged cars were docile at 150+? I read one report that " at 150 the wind noise went away and the car settled in nicely..." one was faster than the other, had to do with the chin spoiler and rear window shape. Myth busters did a test on open or closed tailgate for mileage, they both ran out of of gas (80-85 miles) within 5% of each other, the tailgate UP won! They said the pressure buildup in the open bed of the closed tailgate made the wind go over the truck smoother. the open tailgate didnt have the same high pressure bubble and the back of the cab acted like a parachute with a low pressure area. I see semi trucks with tail cones now.


I’m not sure on anything except the Daytona body and it’s instability over 150 MPH.

Interesting thing about the tail cones. There is a huge exit loss at the back of those trailers. The air is crashing back into the end of the trailer trying to fill up the space, which is lower pressure. That creates vortices which cause drag. It’s a great study to watch the air move around the back of those trailers. It’s a very good object lesson.

Anything you can do to put the air back together smoothly at the end of the trailer reduces drag, and therefore increases fuel mileage.
 
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