Tire Deflectors/Spats

[California98Civic]

Thanks for posting up your testing, as usual, Vekke. You've done of the cooler, "Mad Max" style modding and testing on this forum over the years.

One of the things that will make frontal area created by the tire different and more important than just any frontal area is the fact that it is a moving rough surface, a tread that is designed to force away fluids. The tire face must blast air both under the car and maybe a foot or more to the sides, creating an effective frontal area far larger than the face of the tire itself.

[freebeard]

[IRONICK]

The trend is to stop using those simple deflectors in front of the wheels.
Something else is being used now, you have two examples here:





You must do the same for the rear wheels.

[Vekke]

I have now tried over 10 variations of front deflectors. So far the best two have been the triangle and the D shape deflector. D shape is the best and there is a basic shape physics backing that idea up:


That table also shows why the flat plate that car manufacturers use is not the best option. On that use its not that clear difference as that chart shows as there is the bumber blocking some of the flow making it little bit wedge in a way but still shape is shape and better is better.

That D shape in front is 0,6 to 1,0 percent better than triangle. which is 0,1 to 0,2 kWh difference in my test route.

[freebeard]

That's the way I thought things should go. As I understand it, D-shaped in plan but flatted on the bottom in elevation.

But they're offset inward about half the width of the tire. Is that for the suspension area?

[Vekke]

Currently D is about 15mm narrower than tire on each side. The bottom is still open, it should be closed for best effect. That D shape is tricky for that curb driving situations.

Those oem style deflectors as seen on that red car are not best imo as more air can hit the tire surface.

[freebeard]

This is my design from 2013:



It was sized for a pickup truck but the dimensions are variable. Two pieces not connected on the bottom of the U shape so the conveyor belting can deflect on road strikes.

The lower trailing edge would naturally tend toward a D-shape.

[IRONICK]

The picture with the red car is from the previous model.
In my case, I did not want to cover the suspension arms with the deflector , because I have an air intake for the brakes. Especially since I use wheel covers that provide less ventilation.

[Vekke]

I wrote a article on linkedin conserning the topic and my findings:

[California98Civic]

Originally Posted by Vekke

I wrote a article on linkedin conserning the topic and my findings:

From the end of the article you linked in the quoted section above: "Writer of the article is a well know automotive engineer ..."

Which is the "D" shape that you identify as best? It seemed like the "D" shape was among the best but that it was equal to the "I" shape at 1.17 and the "O" shape. I must have misunderstood.