Partial front wheel covers/skirts question.

[Tesla]

I have been thinking about doing these, and have a temp cover in place, but before I do the permanent versions:
Is it better to have the cover close the gap all around the front tyre, or just close front and top, leaving back open to let air out?
I have seen some comments like rounding rear of wheel arch to help exiting air merge with the side air along body, so I assume there is a need to keep the rear open more than the front and top.
Havesearched around and haven't been able to find the answer to my question.

[Sven7]

Probably a good idea to leave the back open unless it's done perfectly.

[aerohead]

I would vote also to keep the rear open.
With regards to doing some radius back there,I don't have any specific numbers for that kind of a mod.
I went ahead and did them on my T-100.It took a full 8-hrs to do the fabrication and install.
I'm presuming that they will assist the merging of the out flowing stream from the wheel well,with that flowing straight down the side.
If you've driven next to cars in the rain you may have noticed a jet of water-laiden air blasting transversely out the wells.This is what you're going after.
If you haven't seen basjoos AeroCivic,he has the ultimate solution.

[Tesla]

Thanks for responses,
I have seen & read about the AeroCivic, bit extreme for my situation, mine is a Fourby and still needs to retain significant off road capability.
Will stick to the front & top only, though may taper the top down a little at the rear for styling.
The plan is to use a solid lip of about 2" and additional 2-3" rubber which will give flex when the tyre may touch it.
The mockups seem to have had some benefit in improving the coasting ability, but I think they are getting this advantage moreso as an addition to the front airdam.
Want to also look at some kind of attachment at rear of wheel arch to direct air coming from road to go under body rather than up into wheel arch, so was thinking of using some heavy rubber coming out from body horizontally and curving down to point to where the tyre exits road contact. I imagine this would act like a bit of a scraper directing some of the air under the vehicle, obviously it wouldn't be touching tyre, I imagine it would be about a 2" gap.

[jime57]

Originally Posted by aerohead

I would vote also to keep the rear open.
With regards to doing some radius back there,I don't have any specific numbers for that kind of a mod.
I went ahead and did them on my T-100.It took a full 8-hrs to do the fabrication and install.
I'm presuming that they will assist the merging of the out flowing stream from the wheel well,with that flowing straight down the side.
If you've driven next to cars in the rain you may have noticed a jet of water-laiden air blasting transversely out the wells.This is what you're going after.
If you haven't seen basjoos AeroCivic,he has the ultimate solution.

I will just add that on the Honda Insight Gen 1, they included a very generous radius on the rear edge. They took a lot of effort aerodynamically, so I assume it helps a bit.

On the Insight they also scolloped the fender just behind the front wheel. That is imparactical for most DIY folks, but worth noting. Look at some Insight pictures on Autotrader and you will see what I mean.

I like the idea of smoothing in the front and top. That should minimize the amount of turbulence in the wheelwells.

In Hucho, the second best treatment of engine compartment air flow is to channel it out throught the front wheel well. It would require a lot of underneath sealing, probably with a good full car underbelly.

[Tesla]

Had another look at the Honda Insight, still looking at how additional venting could be added at the rear of the front wheel arch, I do wonder how the insight goes with road grime and stone damage on the body panels, without any mud guard, or if the airflow actually deflects most of this.

[Sven7]

Ferrari knew what they were doing back in the 50's.

[Tesla]

The front wheel exits look good, still though, how did they go with road debris coming off the front wheels, and not sure about the open top being aero friendly.

[expensivehobby22]

In general, you want to have a radius on the rearward side of the wheel lip to encourage airflow out of the wheelhouse.

Your wheel shroud looks reasonably good. Just try to minimize the addition of frontal area. Only have it as far out as it needs to be.

[Tesla]

Thanks, still learning something new every day.