Show me your wheel spats!!!...

[blackcivic96]

Alright I thought I chime in here, I am no expert, so I will give some images for ideas

Firstly we just purchased a Chevy Traverse a couple months back. This 3 row, 7 seater (4700lb!) is currently getting 22MPG with my wife driving. (With the roof racks, don't ask)

First, I am hoping to provide an insight as to what the manufacturers are doing in this area. My attempt is second

First is the rear spat:




The fronts do not have any, it seems Chevy is relying completely on the front air dam, for that.


And now my vehicle, I used one piece of (the best I can describe it) a carpet stair tread corner protector I decided to go about .25 inch wider than the tire, then attach with stainless screws.

Scrap left over:




Installed angle one:


Installed angle two:


Just hoping to provide ideas, if anyone has comments, I'd love to hear 'em.

-Dave

[ecomodded]

I am curious of the benefit these would provide,Off hand without really understanding their use i am thinking that a spat ahead of the tire would be of benefit by reducing the amount of air that will pass over the rolling tire, thereby reducing the air resistance on the rotating tire.
The rear of the tire spats seem like they would restrict the air from leaving the rotating tire, causing unneeded drag.

[COcyclist]

Originally Posted by ecomodded

I am curious of the benefit these would provide,Off hand without really understanding their use i am thinking that a spat ahead of the tire would be of benefit by reducing the amount of air that will pass over the rolling tire, thereby reducing the air resistance on the rotating tire. The rear of the tire spats seem like they would restrict the air from leaving the rotating tire, causing unneeded drag.

I was just reviewing the Coventry papers that were on a thread here. There is one by Jeff Howell on Wheel-Wheelarch drag. They tested various front and rear fender skirt combinations and deduced that 80% of the drag penalty came from the exposed lower wheel(tire). In other words, even with front and rear side skirts a majority of the drag came from the air slamming into the front of the tire. I believe that is why tire spats are becoming commonplace, especially on Asian and German cars.

In another Coventry paper they tested "underfloor wheelarch blanking" on an Audi A2. They reduced drag by closing the gap between the belly pan and the tire. The tire spat may solve two problems by managing the airflow hitting the front of the tire and the turbulence of the wheelwell. Super slippery aerodynamic cars would utilize canoe-style boattailing in front and behind the tires. This is not practical for road going vehicles. A mini airdam (spat) in front of the tire can streamline the air around the tire and possibly prevent some turbulence in the wheelwell. Unfortunately, we do not have access to windtunnels to see what the perfect placement and size would be. The best we can do is to seek out similar vehicles and try to copy what the major manufacturers have done. I have been amazed to see how small some of the spats are in front of the rear tires of some Toyota SUVs (often smaller than a deck of cards). If you discount the hours of testing in the windtunnel, it is a cheap, easy fix for the automakers.

[cfg83]

COcyclist -

Originally Posted by COcyclist

...

In another Coventry paper they tested "underfloor wheelarch blanking" on an Audi A2. They reduced drag by closing the gap between the belly pan and the tire. The tire spat may solve two problems by managing the airflow hitting the front of the tire and the turbulence of the wheelwell. Super slippery aerodynamic cars would utilize canoe-style boattailing in front and behind the tires. This is not practical for road going vehicles. A mini airdam (spat) in front of the tire can streamline the air around the tire and possibly prevent some turbulence in the wheelwell. Unfortunately, we do not have access to windtunnels to see what the perfect placement and size would be. The best we can do is to seek out similar vehicles and try to copy what the major manufacturers have done. I have been amazed to see how small some of the spats are in front of the rear tires of some Toyota SUVs (often smaller than a deck of cards). If you discount the hours of testing in the windtunnel, it is a cheap, easy fix for the automakers.

Yes, that sums it up well. The spats work, but the devil is in the detail$ as to how they came about.

CarloSW2

[tvbd56]

Time to revive an old thread!

I made myself some rear wheel spats and after reading up on them more and more I feel like I made them too big. They are made of coroplast and they are cut into 4"x7" pieces and there is 3" showing.



From spats that I've seen on here and the big manufacturers the spats are smaller compared to the ones I made and I'm wondering if I should make them smaller or not.
and this is my air dam which was one of the first aero mods I put on this car and it turns out that it works to block both of the front tires as well.

[California98Civic]

Originally Posted by tvbd56

Thanks for these photos. I have a thought for you to consider. It is possible that these two outer edges are too far out, too close to the outer edge of the tire. When I did mine I saw research for the Prius, second gen I think, that suggested that the outer edge of the spats should be an inch or two inside the outer edge of the tires. It's about how far the airflow gets pushed to the side. You want it to go just far enough to clear the front of the wheel and not so far as to extend the effectual frontal area of the car (via blown out airflow, apparently).

Thanks again,
james

[tvbd56]

Originally Posted by California98Civic

Thanks for these photos. I have a thought for you to consider. It is possible that these two outer edges are too far out, too close to the outer edge of the tire. When I did mine I saw research for the Prius, second gen I think, that suggested that the outer edge of the spats should be an inch or two inside the outer edge of the tires. It's about how far the airflow gets pushed to the side. You want it to go just far enough to clear the front of the wheel and not so far as to extend the effectual frontal area of the car (via blown out airflow, apparently).

Thanks again,
james

Alright I'll try that, I'll cut two inches off of each spat. I have seen ones that are like that before. I'm hoping that there are actually doing something

[arcosine]

[macbuddy]

After reading this thread, you guys got me so worked up, I had to give this a try myself. Even though I wasn't exactly sure how to go about this, I just went ahead and did what I thought looked right. I used the previous posts as a guide.
About 2 weeks ago, and 4 tanks later (~1,800 miles), I can only report a meager .5 mpg increase. I am not sure if this is due to the warmer weather, or a change in my driving. Regardless, I have not seen any negative effects. With my 13.81 gallon tank, I may have extended my cruising range by 6.5+ miles. I think I am gonna leave these on for now. Hopefully, I will find that these do in fact work to my advantage.

[serialk11r]

I think the thing with factory wheel spats being relatively short might have to do with the fact that if you naively extend them down, their "aspect ratio" becomes bad and you can end up with powerful vortices coming off the sides of the spats. However perhaps in conjuction with a "lip spoiler" or side skirts, you could get them lower without this problem.