smooth wheels/hub caps = MPG increase?

[WestonR]

All these flat and moon hub caps and covers sure are expensive. Wish i could find a used set for cheap. Doubt thats going to happen though. Has anyone ever tried to make their own? Out of plastic maybe?

[GasSavers_Loopie]

$69 a set.
http://www.autoenhance.com/trimr.html

Lighter wheels should show the most difference with acceleration/deceleration and suspension. Which lends itself to increased FE in heavy stop/go City traffic I suppose. Once at speed...I don't see how it can make much FE difference. I could be wrong.

I too am curious Brian about how much JUST a racing disk installation changes FE.

[RningOnFumes]

Craigslist for the 14 inch at 50 for the set: http://stlouis.craigslist.org/pts/611297722.html


Ebay 69 http://cgi.ebay.com/ebaymotors/HOT-R...em280193942739


Next cheapest is for 85 a set.
http://www.hubcapmike.com/racing_disc_wheelcovers.html

[GasSavers_Otto]

Keep the weight as low as possible, since it takes more energy to accelerate and decelerate a wheel/tire that has more mass. This is a big deal for handling and in city traffic. At constant cruise speed, not such a big deal, but the ride will be harsher with a heavier wheel/tire.

Wheels may act as turbines, drawing air out of the wheel well and into the slipstream. This may be good or bad, aerodynamically: Good if it relieves air buildup under the car and thereby improves cooling flow, etc.. Bad if it buggers and aggravates the slipstream along the sides of the car. You are paying for every eddy, turbulence, and backflow caused by the movement of your car, all of which impact fuel economy.

On a wet highway, it's interesting to study the turbulence patterns of various vehicles, made visible by the mist and spray. A few years ago, a group of ~30 Porsche 944 guys did a ~500 mile all-day high speed ratrace through British Columbia, much of it on wet roads. The cars all had the same shape, but wheels and tires ran the gamut among Porsche styles. (Some wheels were fairly smooth disks, others had airfoil-shaped spokes to enhance brake cooling, most somewhere between.) You could see wide disparity among them, with some throwing spray well out from the car body, whereas others not.

[Drag Limited]

Any hard figures on MPG increase from .cd improvements?

[JanGeo]

Hey got a friend I do some favors for that is going to buy me a set of speed disks / MoonEyes.

Loopie - are the

http://www.autoenhance.com/trimr.html

racing disks going to stay on the wheels ok ? Any idea how they compare to the MoonEyes like are they heavier or lighter??

The Mooneyes are spun aluminum clear powder coated and the Autoenhance at Stainless Steel.

[JanGeo]

It's a cool rainy day here in Newport but my Racing Disks came into Postall yesterday so when I venture out this morning I will go pick them up!

[JanGeo]

First issue is that the covers cover the valve stem - talk about aero extreem!
Not sure you easy it is going to be to pull them off - there are a LOT of little metal black painted fingers grabbing the rim and it looks like it fits right against the bead of the rim where wheel weights are mounted - should look pretty flush. I think I may give them a coat of tranlucent black to give them a black chrome finish since there is NO chrome on the xB and the polished stainless steel look doesn't quite look right.
Oh yeah just in time for my surprise trip to main in the next week or two - friend is coming in from Japan.

[theholycow]

Hmmm.....I just got an idea. In another thread, someone mentioned that heat-shrink boat wrap is available in clear. If you put it on any random wheelcovers and shrink it tight and smooth, they would then be as good and might look okay, on the cheap.

[OokiiMamoru]

Originally Posted by theholycow

Hmmm.....I just got an idea. In another thread, someone mentioned that heat-shrink boat wrap is available in clear. If you put it on any random wheelcovers and shrink it tight and smooth, they would then be as good and might look okay, on the cheap.

Had a similar thought while looking for ideas in my place of employment. (WM)

Stumbled across a roll of self adhesive clear carpet protector. I could not get the stuff to go on smooth at all, and have no idea if my FE has increased, but the wheels quited down on a 1989 Cadillac Eldardo, and seems to be holding.

I put some duck tape on the lower portion of the front bumper and instead of going under the car the air goes right for the tires/wheels and I had a major increase in noise from the front wheels. Almost thought my transmission was going out on the first go. Talk about nerve recking.

Just the lowering of decipeles was well worth the ten dollars to me, and I have plenty of material to continue to play with. Like experimental tire skirts (yeah it will push in, but will keep the air out.) Covering a few of the crevices along the body of the car, etc. One thing I am interested in is how the material interact with long term exposer to the paint.

OM