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Author Topic: Underfloor aerodynamics Back to Topics
Camry05

All-Star Author
Indiana

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Message Posted: Sep 23, 2013 12:16:25 PM

Have any of you tried bolt on plastic panels for the under body, that claim to clean up the turbulence between the road surface and the car and therefore improve mileage.
REPLIES (newest first) Post a Reply
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Dulaya
Rookie Author Las Vegas

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Message Posted: Nov 2, 2013 3:39:54 AM

Nope. I believe Tesla have that design with their electric cars. The drag coefficient is less than those exotic cars. /watch?v=1kCG-WqpVnI
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the1roadhog
Champion Author Atlanta

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Message Posted: Oct 25, 2013 10:03:20 AM

Ummm, that's a 10-4, backdoor.
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Dennis783
Champion Author Des Moines

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Message Posted: Oct 25, 2013 7:56:39 AM

never needed to, my cars have been GT or R/T editions
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oilpan4
Champion Author Virginia

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Message Posted: Oct 12, 2013 10:20:31 PM

"As a followup to the original question, where could I buy one?"

You buy the materials and hardware then build it.
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Camry05
All-Star Author Indiana

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Message Posted: Oct 12, 2013 8:39:27 PM

As a followup to the original question, where could I buy one?
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oilpan4
Champion Author Virginia

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Message Posted: Oct 11, 2013 2:20:48 PM

"Another crazy idea".....

If its a crazy idea why does tesla, lotus, volt, EV-1 and other note able highly aero dynamic cars use it?
I just think you don't know any thing about vehicles or aerodynamics.
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contiki
Champion Author Ontario

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Message Posted: Oct 11, 2013 6:36:39 AM

Another crazy idea.....
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RalphHightower
Champion Author South Carolina

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Message Posted: Oct 11, 2013 6:07:35 AM

no
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Demomann
Rookie Author Ventura

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Message Posted: Oct 11, 2013 1:15:05 AM

I lose fuel economy when I have any of my underbody panels missing, but I haven't had a chance to improve on OEM yet. Election signs get cleaned up a bit too well where I live.
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oilpan4
Champion Author Virginia

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Message Posted: Oct 10, 2013 9:52:15 PM

Most people are content with 20 to 30mpg because they don't know any better.
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oilpan4
Champion Author Virginia

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Message Posted: Oct 10, 2013 9:49:41 PM

"I'm not sure I believe this."
This is basic aero dynamics, what's so unbelievable about this division of established fluids science?

"I think it's just another idea someone had for selling a product and making some money."

No one is selling anything.
If you want a belly pan go buy a few dollars worth of chloroplast (plastic cardboard) from a sign shop or collect political ads the day after elections.

If you want an air dam use lawn edging or old conveyer belt.
Strangely enough lawn edging makes a better air dam than most OEM air dams do.
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OilerFan
Champion Author Tulsa

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Message Posted: Oct 10, 2013 7:57:53 AM

I'm not sure I believe this. I think it's just another idea someone had for selling a product and making some money.
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GLM4205
Champion Author Toledo

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Message Posted: Oct 10, 2013 5:13:46 AM

No
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oilpan4
Champion Author Virginia

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Message Posted: Oct 10, 2013 2:35:11 AM

Another modification completed but that I am unable to use during warmer weather is my grill shutters.
A good addition for cold weather operation, faster warmups, better aero (like the new trucks) and will hold the heat in the engine bay after shutdown longer for trips to the store.
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HotRod10
Champion Author Wyoming

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Message Posted: Oct 9, 2013 3:57:16 PM

My apologies oilpan. I must have confused you with someone else; I was thinking you had a newer truck.

Isn't it amazing how good the gas mileage was for those older vehicles compared to the '90s and '00s. Especially since, like you said, aerodynamics was a bad word when it came to trucks. In the last 10 years they've finally gotten back to the mileage that was typical 30 years ago.
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oilpan4
Champion Author Virginia

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Message Posted: Oct 9, 2013 3:16:01 PM

"You should take this to GM! I'm sure all those engineers with advanced degrees in fluid mechanics would be interested in the modifications you made to their designs that increased the mileage of their vehicle by 10%."

You think I only get 10 to 15 mpg with my suburban? HA!
No, it gets a little over 20mpg on the highway.
My suburban's body style was produced from 1978 to 1991, in the 70s truck design and aero dynamics were never uttered in the sentence together, anyone that did so my have been caned or whipped in the spot.

A 1mpg improvement is a 5% improvement to me, A typical stubby OEM air dam improves fuel economy by around 5% to 6%.
Ideally the air dam would touch the ground.
Any mechanical engineer that has passed fluid dynamics 1 knows this.
Any one who has ever driven a truck off road knows that a huge low hanging air dam would be torn away.

My air dam is not a typical truck air dam. It comes down 9 inches and is wide enough to double as a front tire spat*. It also only covers 2/3 of the front because of how my intercooler is mounted. Most OEM truck air dams only come down 3 or 4 inches and do not block air flow to the tires.
When I incorporate the intercooler and air dam together completing the build I expect to see closer to a 10% improvement.
Before I installed my air dam I had no air dam below the bumper, air would just flow up under the suburban and get hung up around turbo charger piping, steering and frame structures and hit the surface of my very un aero dynamic tires.

* A tire spat is a structure that acts as an air dam or spoiler to deflect air away from the tires. They improve aerodynamics and reduce wind noise.

I have not come up with anything new, I am just adapting a well known feature to better fit my application, which is highway driving.
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Chazzer
Champion Author Nevada

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Message Posted: Oct 9, 2013 1:41:36 PM

My air dam broke ... after I reinstalled it my gas mileage improved dramatically!
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HotRod10
Champion Author Wyoming

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Message Posted: Oct 9, 2013 11:12:05 AM

"I picked up 1 to 1.5 MPG when I air dammed my suburban."

You should take this to GM! I'm sure all those engineers with advanced degrees in fluid mechanics would be interested in the modifications you made to their designs that increased the mileage of their vehicle by 10%.

[Edited by: HotRod10 at 10/9/2013 11:12:44 AM EST]
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oilpan4
Champion Author Virginia

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Message Posted: Oct 8, 2013 3:00:55 PM

"Any savings would be negligible, you wouldn't even see it when checking fuel mileage."

I picked up 1 to 1.5 MPG when I air dammed my suburban.
So you're wrong.
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TomB2
Champion Author St. Louis

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Message Posted: Oct 7, 2013 3:52:00 PM

Any savings would be negligible, you wouldn't even see it when checking fuel mileage.
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HotRod10
Champion Author Wyoming

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Message Posted: Oct 7, 2013 3:40:25 PM

Mine's fairly smooth already, except under the engine and where the exhaust is. Not a good idea to bolt plastic panels over either of those.
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Houckster
Champion Author Atlanta

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Message Posted: Oct 5, 2013 10:10:45 AM

BOYRR writes: "not going to save a thing at normal speeds."
_____
Correction, it will save fuel at normal speeds just as closed windows do. Normal speeds include the 45-80 MPH.
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sagnat
Champion Author Riverside

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Message Posted: Oct 5, 2013 2:05:01 AM

My 2012 VW has several under carriage panels.
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Camry05
All-Star Author Indiana

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Message Posted: Oct 1, 2013 7:37:03 PM

drydem, thank you, did not know that the prius 3rd gen, oil change access door tends to warp.
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oilpan4
Champion Author Virginia

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Message Posted: Oct 1, 2013 3:00:28 PM

"not going to save a thing at normal speeds."

Define normal speed.
Are we talking 25 to 45 mph or 65mph+?
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OceanArcher
Champion Author Mississippi

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Message Posted: Oct 1, 2013 1:09:09 PM

Mine came with 'em
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Boyrr
Champion Author Allentown

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Message Posted: Oct 1, 2013 12:20:50 PM

not going to save a thing at normal speeds.
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drydem
Veteran Author Maryland

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Message Posted: Oct 1, 2013 7:44:21 AM

The 2010 Prius already has a series of plastic panels under the body that lower the aerodynamic coefficient Cd by .01 to .02 ... The plastic panels under the engine is insulated to prevent thermal loss. The Prius' under body (engine shield) plastic panel's oil change access door has a tendency to warp and fall off.
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jl1rp
Champion Author New Hampshire

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Message Posted: Oct 1, 2013 12:53:38 AM

no
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oilpan4
Champion Author Virginia

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Message Posted: Sep 27, 2013 1:12:44 PM

Install the chip last, that way you have some time to verify the claims. The problem with chipping a N/A gas engine is that the gains they advertise no one really sees.
The only application where chipping the engine computer can make a huge difference in power and fuel economy is on tubodiesels. These chip makers will advertise the gains for the turbodiesels and they will be true, but what they wont do is go out of your way to tell you diesels respond a lot better to chipping than a gas engine and they will advertise the gains in power and fuel economy for the diesels in a way that makes you think you will see something similar if you put one to work on your gas motor.
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Houckster
Champion Author Atlanta

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Message Posted: Sep 26, 2013 4:53:58 PM

I looked at the GForce chip and there are an awful lot of dissatisfied people. And are the positive reviews real? Two nights ago on the PBS News Hour, they discussed a growing problem with internet reviews: a good portion of them are fake. One woman was interviewed and she was quite up front that she's paid $4 per positive review even when she's never seen the product she's reviewing. Particularly distressing was the review where the GForce chip fried his ECU that cost him $1000 to replace.

I won't write the GForce chip off completely but I'm going to wait until I know a LOT more before I try to install this chip.
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alphanyr
Champion Author Connecticut

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Message Posted: Sep 26, 2013 4:45:27 PM

OK
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oilpan4
Champion Author Virginia

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Message Posted: Sep 26, 2013 2:30:50 PM

"I would love to implement this on my Ranger but the aftermarket isn't doing much if anything for the Ranger and I probably don't have the skills necessary to fabricate something on my own."

You have a newer ford ranger so you will love this:
38mpg ford ranger

This guy "wasted his time and money" making a normal 25mpg ford ranger into a 35 to 38 mpg vehicle.

But just think of how much time and money people spend when they switch from a 25mpg light truck such as a ranger to a small 35mpg car.
If you go to a dealer it will be quick, but they are going to make several thousand dollars off you, they will screw you on trade in value for your truck then sell you a car for top dollar.
If you "for sale by owner" your truck and get the replacement car by a privet sale it take lots of time.
And now that you have a car you can't do any more truck stuff, so every time you want to move something big you have to spend time and money begging, barrowing or renting a truck to do it.
On top of that any time a vehicle changes owners the state makes a few hundred dollars off you.
Modifying the vehicle in this case was clearly the best option.
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oilpan4
Champion Author Virginia

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Message Posted: Sep 26, 2013 2:07:42 PM

"Believe me, you are totally wasting your money for nothing."

I fabricated an air dam for my suburban out of scraps and left over material. I picked up 1 to 1.5 MPG.
That means I am saving at least $4 or $5 per fill up. How is that wasting time and money?
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Houckster
Champion Author Atlanta

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Message Posted: Sep 26, 2013 10:39:09 AM

Oh how it love the comments that brush off an idea without a first thought.

Diverting air from the underside of the vehicle WILL help people save gas if they do a lot of highway driving. If most of one's driving is around town it won't help much.

I would love to implement this on my Ranger but the aftermarket isn't doing much if anything for the Ranger and I probably don't have the skills necessary to fabricate something on my own.

[Edited by: Houckster at 9/26/2013 10:40:05 AM EST]
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Boyrr
Champion Author Allentown

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Message Posted: Sep 26, 2013 6:16:27 AM

waste of time and money
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MertieMan
Champion Author Lexington

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Message Posted: Sep 26, 2013 5:12:49 AM

Believe me, you are totally wasting your money for nothing.
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oilpan4
Champion Author Virginia

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Message Posted: Sep 25, 2013 9:41:22 PM

You are talking about a belly pan.
They require a lot of fabrication work and materials.

If you use an air dam you get most if not all the benefit of a belly pan with $6 worth of lawn edging hung under the nose of the car.
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WEPSMAN
Champion Author South Dakota

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Message Posted: Sep 24, 2013 9:17:52 AM

Nope, and not interested.
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33gort33
Champion Author Indiana

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Message Posted: Sep 24, 2013 8:39:52 AM

nope...and I don't believe they would make that much difference in saving $3.50 fuel.

The cost doesn't offset the savings (*if any*)
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Glasman
Champion Author South Carolina

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Message Posted: Sep 24, 2013 6:43:09 AM

haven't seen any "belly pans" in years- we used them back in the day when drag racing.
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RalphHightower
Champion Author South Carolina

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Message Posted: Sep 24, 2013 5:45:10 AM

no
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CactusBobs
Champion Author Arizona

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Message Posted: Sep 23, 2013 9:03:27 PM

Volvo did this on the 240 , from the mid 70's until the 240 ended
first it was made of metal and later it was plastic
the 240 was never the king of MPG , so i don't think it helped it much , but it did help channel air across the engine , for better cooling of the front brake rotors and under hood area
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OilerFan
Champion Author Tulsa

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Message Posted: Sep 23, 2013 7:45:42 PM

haven't seen them and don't know anyone that has tried them.
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forresj
Champion Author Wilmington

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Message Posted: Sep 23, 2013 7:40:25 PM

no
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alphanyr
Champion Author Connecticut

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Message Posted: Sep 23, 2013 4:16:52 PM

ok
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