DUMB Wheel question
 

https://www.hubcaphaven.com/mm5/grap...wheelcover.jpg

will taping over the little vents/holes in my hubcaps for long trips help with aero or mpg? obviously they are there for brake cooling, but i dont plan on doing any braking while driving for hours in the middle of nowhere on the interstate with cruise control set to 90mph...

would duct taping over the holes just for a day add any benefit? even if its 1mpg?

Those hubcaps look already quite aerodynamic, I wouldn't hold my breath for an actual MPG improvement if you cover those vents.

The dumbest question is the one you didn't ask. ;)

That said, I agree those wheels look pretty aerodynamic already. If you have time to test the duct tape mod, it would be nice to have actual data. But I'm guessing any benefit would be marginal.

Edit to add: Maybe you could use your road trip as a mpg test. Use the duct tape mod for half the trip, and remove it for the other half. See what happens.

Are all 4 identical, or do you have symetical caps for left and right?

I had aero caps on the Prius where all 4 were identical. That meant half appeared to be facing the wrong direction.

Just checked. Yeah they must all be the same. Cuz the two on the left side of the car are facing a different direction than the two on the right side haha

So it can't hurt to just do the two on whichever side is retrograde to the direction of travel.

What do you mean? And I’m gonna try to tape over the holes for the long trip to Arizona. If people can do pizza pans and survive city traffic, I think I could survive highway

'Can't hurt' or 'retrograde'?

Can't hurt = not worth doing.

retrograde = the side that sucks air out instead of in.

Aluminum tape looks better than duct tape, and leaves less residue.

I taped them up. Let’s see if the dollar tree grey duct tape holds on! Blends pretty well

taping over
 

Since the sub- Cd 0.17, M-B Vision EQXX has non-ventilated wheel covers, and low drag was of paramount concern to M-B, it implies that, like so many other 'record' vehicles: when you want really low drag, get as close as you can to MOON wheel covers.
One wind tunnel investigation by John Shinella of GM, specifically tested tape on the wheel covers of the 1982 Pontiac Firebird Trans Am. It registered the lowest drag of any configuration examined.
Renault, for their sub- Cd 0.19, 1987, Vesta-II concept, essentially 'taped' all but one opening in their wheel covers. It obviously took care of brake cooling, plus allowed for the valve stem access. Also, the actual opening on these covers were uni-directional in design. Something of interest to us.

You can have lefts and rights if you roll your own.
https://ecomodder.com/forum/member-f...8857-6lcms.jpg

I don't want to go too far off topic, but I got this idea...
The main reason (other than looks, but this can be disputed) for NOT having fully covering moon-caps (and closing up from the inside and below) is brake ventilation.

So how about if there would be small flaps in the front bumper which would open each time the brake pedal would be pressed, scooping air from the front and channeling it onto the front wheels' brakes.

The flaps would mess up aero, but only during physical braking, so wouldn't impact FE.

brake flap inlets
 

This sort of thing has already been proven at Bonneville in the streamliner class. In the 1930s if memory serves me.:thumbup:

Access to the valve stem?

Granted:thumbup:

But you access the valve only in a periodic, controlled way, and never when rolling.

So the access can be by removing or bending the cap, a removeable cover over the hole, etc.

Messing up aero while braking could eventually improve braking, and decrease wear and tear of the brakes too. Not a bad idea at all, yet controlling the flaps may add a layer of complexity and weight...

controlling
 

The brake light circuit could be the trigger. It's enabled at all times.
Since rotors and drums have the facility to store quite a bit of heat flux, actual flap opening could be delayed on a timer, as well as the closure.
An interrogating remote infrared sensor, calibrated for open circuit threshold would initiate the end of the cooling cycle once rotor or drum temp. parameter was satisfied.
Low power 12-VDC solenoids could actuate the flaps against a mechanical spring preload and viscous damper.
Or wire them 'fail-open'.

Update, regular duct tape doesn’t hold up well at 90 mph and head winds haha. May have to find some grey gorilla tape versus plain duct tape

Hundred-mile-an-hour tape got it's name for some reason.

It's also not so smooth as it would be desirable for an aerodynamic purpose...

Also, you need to consider what would happen if one of the flaps fails. If one side gets cooling airflow but the other does not, that may result in uneven braking (i.e. pulling to one side). That might be dangerous, depending on the situation.

Another consideration would be legality, in the event of a crash. If the opposing attorney finds out you modified the braking system and it failed, they will have a field day with that.

The flaps could be physically connected to ensure they always open & close symmetrically.

Also, I think the slight asymmetry in aero wouldn't be noticeable - many cars already have this. For example - no side mirror on the passenger side, antennas or flags on 1 side, asymmetrically open windows, dents and missing parts...

Not more than any other mods that are done by Ecomodders, ricers, Rednecks;)

The braking system itself would not be altered, the flap actuators would piggyback on top of it, like the braking light - If the light fails the brakes still work. The only thing effected by the failure of the flaps system is brake cooling. Similar effect by full mooncaps, closing the wheelwell gap, better undertray, etc.

The attorney would have to be a hell of an ambulance-chaser to figure out how the device works and what's its purpose :turtle:

Just don't have the patent application in the glove box. :)

Interesting discussion on flaps for brake cooling. I'd be tempted to try a shape memory alloy flap actuator so the flap is opened when the brake exceeds some temperature or other. AFAIK all cars need to pass a brake test which consists of 10 consecutive rapid stops from 90% of maximum speed, so they should withstand a fair amount of heat soak.

Thermostatically-controlled flaps may be a good idea, yet eventually the flaps wouldn't even be required considering normal driving conditions.