Heresy! Smooth Wheel Covers- Myth Busted!!!

[aerohead]

Originally Posted by easythereturbo

So much win here on page7. Good enough > perfection. Emotional investment.. and black wheels so so trendy. But to each.

I feel the same way about large wheels, so trendy. But what sells on the showroom floor matters to car makers more than anything. Understandably. So wide glossy black 22x10's sticking right up to the fender edge it is. Aero be damned.

Here is one for anybody who thinks you need huge wheels to have a sporting time in a car..

IMO the FRS dev team got it right when they spec'd skinny LRR tires as standard on that one. And the fun to fuel cost ratio on that vehicle happens to be very high.

CAR and DRIVER did the same thing on a Corvette in the 90s.It nearly scored as high a lateral G rating on the skidpad,as with the big fatty,OEM speed rated rubber. Isn't rubber compounding wonderful?

[freebeard]

Originally Posted by aerohead

...re-test the Pontiac at Windstream,with and without rotation,and publish the difference.

That is pretty genius, A-B-A test the wind tunnel.

On the Beetle? Black? ... So, boring old silver.

Those are the obvious choices, but if I didn't think I'd get bored of it, a classic artillery spoke look:

https://classicgaragellc.wordpress.c...l-restoration/

http://www.2040-parts.com/1920s-1930...sler-i1966008/

So, maybe satin black with the wood-graining done in Plastidip?

[ptjones]

I have a 2013 FORD CMAX with 250K miles and I have been using flat LEXAN wheel covers for 240k miles and I gained 2 mpg which I have tested many times. I have read they increase 4 % mpg's. https://fordcmaxhybridforum.com/uplo...1382541182.jpg My mpg average for the last 140k miles is 52.8 mpg.

Paul

[freebeard]

Clear Lexan?

How are they adhered?

[TimRogers]

Originally Posted by aerohead

The only way to factually determine a 'downside' is, to re-test the Pontiac at Windstream,with and without rotation,and publish the difference.Otherwise,it is scientifically impossible to know,one way or another,and pure speculation on your part.

What I should have said was that that the Lockheed testing was incomplete and not reflective of real world situations. I think the coast down testing that our members do here is more relevant than static wind tunnel testing, at least for the design of the underside, fender openings and wheels.

[gumby79]

Originally Posted by freebeard

Clear Lexan?

How are they adhered?

Appears a single bolt in the center through an aftermarket center cap press fit into to the wheel.

[JulianEdgar]

Originally Posted by ptjones

I have a 2013 FORD CMAX with 250K miles and I have been using flat LEXAN wheel covers for 240k miles and I gained 2 mpg which I have tested many times. I have read they increase 4 % mpg's. https://fordcmaxhybridforum.com/uplo...1382541182.jpg My mpg average for the last 140k miles is 52.8 mpg.

Paul

Very neat.

[ptjones]

Originally Posted by freebeard

Clear Lexan?

How are they adhered?

I used a 1/4"-20 x 2" SS screw with 1/4"ID x 1.5" fender washer thru a 1/2"OD/ 1/4" ID x 1/2" long Nylon bushing. Machined a 2"Diameter aluminum plug w/1/4"-20 threaded hole to go inside the backside of the wheel to screw in the 1/4" screw. Used silicon rubber to glue in the plug so it could be removed and stuck back in when replacing tires. Use Lock Tight/Permatex medium strength glue on threads to keep screw from unscrewing. Used a nylon 1/4"-20x 1.5" screw near the edge of the cover screwed thru the cover and on the inside I have a 1/4"-20 nylon nut to lock the screw in place, this keeps the cover from turning when stepping on the brakes and damaging wheel spokes.
On the inside of the cover at the edge I use foam window seal tape 3/16"H x 3/8" W to stick on the inside of cover and go between the wheel cover and edge of the wheel all the way around. When it gets hot I have had problems with the tape adhesive losing grip so have used Supper Glue on the cover to stick the the foam tape on better.

Paul

Paul

[aerohead]

Originally Posted by TimRogers

What I should have said was that that the Lockheed testing was incomplete and not reflective of real world situations. I think the coast down testing that our members do here is more relevant than static wind tunnel testing, at least for the design of the underside, fender openings and wheels.

*FKFS had three wind tunnels. One was a rolling-road type. Fachsenfeld reports the differences in drag they measured, with and without rotation. The results would have to be considered in the context of the typical passenger cars of the day.
*General Motors also explored rolling-road wind tunnel results around 1953 and reported that the difference in data was numerically insignificant,and could be easily compensated for,through simple modifications of tires during static testing.Again,the conclusion would have to be taken within the context of the reporting timeline.
*Wolf H.Hucho basically said the same thing in 1987.For high-speed sports cars and race cars it was another matter.Especially open-wheeled race cars.
*I don't believe that there's any disagreement as to the superiority to the rolling-road technology,however,any arbitrary extrapolation regarding the magnitude in error of drag coefficients derived in earlier,static-wheel testing would be un-founded and dubious at best,unless actually backed up by re-testing of a given specific vehicle,with and without the rotation and moving floor.This is my main objection to Mr. Edgar's claims. There exists no 'a priori',generalized knowledge of drag variability as a function of wheel rotation/stasis. Any excursion from this 'condition' would demand scientific verification,on a case-specific basis.
We could attack Julian for not employing laser-doppler-anemometry when compiling his pressure study data.If the results are the same,or within some standard deviation,do we want to go there?

[ptjones]

When I am doing testing, when I take the covers off to clean covers and wheels, it is easy to see the MPG difference on my trip MPG gauge.

Paul