Shield the tires - will it help?
 

I'm not sure. Sorry for the cell phone pics, but you get the idea.

http://i287.photobucket.com/albums/l...ez/photo-3.jpg

http://i287.photobucket.com/albums/l...ez/photo-2.jpg

Whats the goal here? Does an open wheel well into a rounded tire edge (as from the factory) have a lower drag, or does this idea, with the sharp edges and somewhat blunt angle? I'm thinking the reasoning is that the spinning tire creates quite a bit of turbulence, and keeping air out of the wheel wells is just generally a good idea. But I have no intuitive feel for whether the blunt angle of the front piece would just wash even more wake out to the sides of the car.

Would be made of abs plastic and bolted to the bumper. I can't imagine any benefit or loss will be especially noticeable in mpg testing.

So what do you guys think? Either give me the motivation to knock em out, or save me hours of wasted time, haha.

I'd be curious. I upsized my tires/rims from 175/65R 14's to 195/60R 14's and upped the rims from 14 x 5.5" wide to 14" x 6" wide. My rims are lighter than the stock steel wheels though.

I for one would love to find out what fairings would do for tires/wheels.

I just realized that this design is kind of like a "canard", often used in racing.

From: Automotive Aerodynamics - Sport Compact Car Magazine
"canards generate strong vortices that travel down the sides of the car and act as a barrier. If the canards are positioned correctly, these strong vortices act to keep high-pressure air around the car from entering the low-pressure underbody region, thus maintaining more downforce. If air was allowed to enter the underside, the pressure would inevitably rise, reducing downforce. Therefore, these strong vortices act like a virtual curtain or dam, restricting higher-pressure air around the car's sides from entering the underbody region. As a result, the low pressure under the car is maintained and downforce is maximized. Unfortunately, canards are not very efficient, since the strong vortices create a significant amount of drag. They are more useful for fine-tuning aerodynamic balance."

This is kind of ridiculous though:
Splitters-Canards-Winglets - CB7Tuner Forums

It will help, most if you properly fair the device gently so the outer edge of the tire is protected from wind blast. Also, air turbulence behind the tire should be faired, and that's the other half of the battle.

Aye. The angle of the front fairing may be fairly steep if the wheelwell happens to be a cooling air exit. You could tape on a few streamers to check how the air flows now. Behind the wheel, you want the usual 15 deg or so recovery, or a continuous shape to the rear wheel, and you want a rounded front edge as well. This stuff pays well for detailing as well as basic shapes.

This (small) picture might be of some use
http://image.circletrack.com/f/techa...4_aero_5_z.jpg

Can't read anything on the picture. Can you resize it. Where did you extract it?

I'm on a public computer right now so not much I can do right now but the image is just a link from here

http://image.circletrack.com/f/techa...4_aero_5_z.jpg

The basic idea is that the air coming off the front of the car (to the sides) has some lateral momentum and may, in some designs, largely skip over the wheel well openings. This came up in discussion about the diverters I put on my car a while back (you can see pics in my album).

I seem to remember MetroMPG testing front wheel skirts for his metro and not seeing any improvement IIRC.

My personal concern is that my wheels are open spokes. I was worried air flow was going into the wheel and the open spokes are causing drag. That is why the wheel fairings / skirts interest me. I guess I'll have to research the differences of wheel surfaces.

Found the bigger version
http://image.circletrack.com/f/94035...4_aero_5_z.jpg
And the text that goes with it-
"As the car travels through the air, some of the airflow is directed around the nose and to the sides of the front fenders and wheelwells. If the sides of the nose are angled from a top view, the air will flow out away from the wheelwells and create a very low-pressure area just outside the wheels. The air under the hood is mostly stationary, and some of that air rushes to the wheelwells to fill the void created by this suction. This creates a low-pressure area under the hood, and the pressure differential between the top and bottom creates the downforce needed to provide more grip in the front of the car."
From- Aerodynamics - Tech & Definitions - Circle Track Magazine

Probably not 100% true for many FWD cars (like mine) since the wheel well is separated from the engine compartment, but the idea for the outside flow is relevant.

I think that a tire strake can help, but it would be better if it had a smoother front i.e. a long panel that angled from near the front of the car back to join with the piece you are showing. The underside could begin to push the air down and around the face of the tires, too.

Those look like they'd be forcing the air pretty far to the sides and creating a lot of high pressure in front of them. While blocking the tires is beneficial, you might want to make those longer and at a softer angle, preferably starting from near the front of your bumper.

Though on the Corvette C6 ZO6, there are wheelwell extensions that are completely perpendicular to the car's surface, as well as a soft, rounded exit for air. There's one at a local dealership here, and I'll see if I can take some pictures of it sometime. For now, here's these:

http://www.bryandickey.com/old/image...p-1280x960.jpg

http://www.theautochannel.com/news/2...27178.1-lg.jpg

You can see the flat deflector in the front in that picture, and the wheelwell inside is curved to meet the side behind the front tire.

http://www.z06vette.com/gallery/imag...1_Image006.jpg

It also looks like they use a hard edge behind the rear tires:

http://www.cargurus.com/images/2007/...pic-31863.jpeg

The Corvette is able to get 22 highway MPG because of it's very low drag.

Thanks aeromodder! That is quite interesting. GM must have found that shielding the tires was better than not. But the width of their piece of quite small. I wonder if "tripping" the air flow over that hard edge helps make a curtain of air down the side of the vehicle.

I'm sure my plan would work out better if I bring the front piece out way forward on the bumper... but that is a lot more material, and more difficult to cut & shape. Hmmm....

Deezler, have you looked at what Tasdouille has done to his Mk III Jetta for his 79 mpg mileage run? He shielded the tires much lower. I like the Corvette style flap. Wiki Gurney flap and see what a little lip did for a rear spoiler wing.

http://ecomodder.com/forum/showthrea...15-a-4805.html

my car (peugeot 106) has these as stock, but that looks too steap. blend it into the body more.

I believe the best way to shiled you tire is not a tool install on the outside, but instead on the inside of your wheels. For protection of wheels and tires the best way is definitely the FLATS OVER System. It is made of rubber so it does not transfer impact from the contact of the floor to the wheels in case of bumps and flat tires.
It is also efficient against fire arms. I saw it on a test in Italy and got very impressed. They drove something like 100Km with a flat tire, than shot the tire, then the tire came off after some 50Km flat and shot at and still the car maintained perfect driving conditions. I just got one for my car and some for my company’s cars as well. Easy to install and uninstall to transfer to other wheel of the same size. Any mechanics can do it following the manual. Highly recommended. I found them at Google at first.
It might sort your problem with no difference in your car appearance.

Sure looks like spam to me.

Spam? Yes. Triggered probably by "shield the tires."

Its an anti-car jack, abduction device to allow driving off when the tires are
shot out. A big, fat rubber donut that installs on the rim, inside the tire...
Strangely, it reminded me of the US Pres being denied a hybrid vehicle by his
security forces.

Looking to find any possible connection with the topic of the thread, any
contribution to better MPGs would be limited. It would add flywheel effect,
and might help somewhat at maintaining steady velocity. But would hurt
greatly in town where frequent accelerations are called for.

Flats Over

Yea, I checked it out too and it's a pretty neat product (looks like a huge pain to install). But it would really add to rotating mass and - thinking about bicycles - that would consume a bit more power on acceleration. Could help out any sort of electric regenerative brakes I imagine, but I have no idea how those really work.

OffT: In the fuel shortages that will turn the world into a Mad Max sequel, those puppies would come in very handy. You can bet there will be no shortage of bullets.:eek:

OT: Shield the tires!! They are #2 behind the behind of your car in drag production.

Seems like a good idea to make conduits from the hot engine compartment out through the engine bay sidewalls and the fender liners, to draw that hot air out and thereby improve cooling efficiency. The moving car is, after all, a sort of linear pump, so may as well take advantage of it.

Efficient cooling inlets are only half the battle: It is equally important to provide an efficient outlet, too.

Ha, yeah it was his first and only post. Not trying to protect the tires.... just keep airflow off of them (as much as possible).

Orange, #2 source of drag? Really? Dang, that might be enough inspiration for me to get back to making something up here. Kind of difficult - the best solution would have a formed piece that curves nicely, to straighten out parallel to the vehicle axis by the time I get to the wheel well, but my abs plastic is rather rigid. Perhaps this calls for some thinner material.