Scion xA aero mods

[whokilledthejams]

I like the hood-gap-gasket idea, so I went and scrounged up some rubber weatherstripping/gasket. Of course, when I attempt to test-fit it, it's too small. The gap isn't that big, but the way the hood of the xB is shaped, I can't easily mount what I have.

I guess a trip to Home Depot is in order.

I still need to replace the coroplast in my air dam/grille block with something smoother. That is to say, expanding foam + bondo. Luckily, a significant part of my car is hand-painted in flat black paint, so I can ghetto-rig all sorts of crap and cover it up well.

[NeilBlanchard]

Hello,

I made some rear wheel skirts this weekend:



I'm not real happy about the acrylic glass -- the stuff is pretty brittle, and where it curves down and under at the front and back -- the tape keeps pulling off. I bought a heat gun to try and soften it up and let it form to the curve, and this may have helped a little...

At first, I tried to use just the acrylic glass, but the air pushed them in and they touched the rims (no matter how much a carved the edge...), so I added the 1/8" x 3/4" aluminum bar, and this seems to have helped.

I think I will do them again (using these as patterns) and use Coroplast (if I can find some). I was hoping the the transparent material would be less noticable, but I think the Coroplast would be a better look -- because we WANT to draw attention to ourselves, right?

Tomorrow, I'll see if they survive the commute to work.

Next on the agenda: foil tape on the alloy wheels to see if they can be made a little more aerodynamic!

[Xringer]

But, I'm wondering why you have them cut out in the bottom (around the center area).?.
Almost all the skirts I've seen were flat across the bottom..

I think Coroplas might be the better way to go. It's much lighter than acrylic/Plexiglas(?).
If that stuff were to fly off the car, it might not be something anyone would want hit or be hit by..
Whereas a piece of Coroplas weighs about the same as cardboard..

I have two pieces of blue Coroplas one is 2x4 feet and the other is
about 24x32 inches. I used some for an airplane tail..
http://i46.photobucket.com/albums/f1...PA32D/d0ce.jpg
It looks a little lighter blue in this pic..

Anyways, if that's enough make a pair of skirts, I'll sell the stuff to you cheap.

Cheers,
Rich

[NeilBlanchard]

Hi Rich,

The bottom of the body panels curve well inboard of the tire on the xA, and with the Plexiglas, I had to cut it this way to clear the tire. If I can get Coroplas (sp?) I should be able to form a wedge to flare the bottom out (just) beyond the tire, so the bottom edge could be considerably lower down; covering a majority of the tire.

I am going to contact the local sign shop (right in Maynard where I live) and try to get some dark blue Coroplas. If they don't have that, I think I'll use black. The light blue is my third choice, I think. I'll need each to be ~30" x 18"-20". I'm also hoping to avoid needing the aluminum bar...

[Xringer]

Coroplas is stiffer than cardboard, but it's still darn flexible.
My guess is you will need the aluminum bar to keep it from flopping at highway speeds.

On model airplane wings, 5/32" steel rod (called music wire) is used to
reinforce coro. You spray a little silicon inside one of the little channels and then force the steel rod inside.
This wing has a 16" music wire about 2" behind the fuel tank.
http://i46.photobucket.com/albums/f1...SPA3D/654d.jpg

I'm not 100% sure, but I don't think my Blue coro is the light blue version.
But it does look lighter in the pic (above)..

It's a little tricky painting coro, since it has some kind of coating over it.
I've noticed the paint on my stuff isn't too durable. I've heard of guys
heating it with a propane torch to burn off the coating. That's the tricky part, not scorching the plastic so bad it melts.

My fav for models is the White or Yellow. I like the way it looks and it seems to cut better. The darker colors almost seems softer for some reason.

I just got back from Auto-zone and they didn't have any metal tape.
I'm gonna haft to wing it..

[NeilBlanchard]

Hello,

Thanks for mentioning the piano wire -- that will help a lot.

I got metal foil tape at the local hardware store, and the large home centers will also have it; often in the heating\ventilation section.

[Xringer]

piano wire has to be a lot thinner..

I was just at Lowes and found the stuff I wanted, it was a big wide roll of
aluminum flashing with adhesive (w/ pull away paper) on one side.
It was in the roofing dept.. But, it was more than I needed and cost
around $24 for the roll..

I may try cutting some plastic plugs for my rim holes, if I can find some plastic & glue that will work together..
---------

I've been thinking about how to make a bow at the bottom of a wheel skirt.
If you had a 5/32" steel music wire installed with a 1/2" sticking out both ends and could have a little L-bracket (or Z-bracket) bolted in on both sides of the wheel well..
You could use 5/32" holes in the brackets, and flex out the bow and plug the ends of the music wire into the holes.. That gives you a bow and fore-n-aft mounting..

------
If you had a fat molding around your wheel well and your wheels didn't stick out too much, you might be able to drill (2) 5/32 holes in the molding(on the inside, facing each other).
Then cut the coroplas to fit inside the wheel well.
Install the music wire with 1/2 protruding, flex the bottom and plug it in..
Maybe use a couple of smaller rods up on the top to hold it in up there.
You would have to be sure to make the bottom wider, so it could bow and still fit inside the molding..

[NeilBlanchard]

Hello,

I've determined that the approximate frontal area of the Scion xA is ~18.01 square feet. [See adjusted number below] I inserted this photo into DataCAD 12, scaled it based on the measuring tape just below the bumper, and I then carefully traced the outline of the car with a polyline, and the hatched it with a 1'-0" square grid.

Now, there is some distortion due to the camera being at a point (this is not a true "elevation" view). To minimize this, I used the zoom lens on it's longest focal length, and tried to position the height of the lens to ~1/2 the height of the car. The height scales to ~4'-2 1/2" whereas the specification is 60.2" (~5'-0 1/4"), and the width scales to 5'-1 7/8" vs 66.7" in the spec. so the actual area is like a little greater. In fact, the width is ~19% low and the height is ~7.75% too low, so that averages to 13.375%, so:

18.01 + 13.375% = 20.42 sq ft

[Edit: I will take another photo with a longer lens to try to reduce the error, and post the results later.]

[xbUser]

With the hood taped or rubber gasket installed, what improvement you have noticed? Will the ventilation air becomes cooler? or any mpg increases?

[NeilBlanchard]

Hello,

Taping over the upper grill and installing the flush lens on the fog lights added ~5mpg; and had no appreciably affect on the coolant temperatures. Good change -- and easy, too.

[NeilBlanchard]

Hello,

Okay, from Daox's CdA list:

Make Model Year Cd Height (In) Width (In) Frontal Area (ft^2) CdA
Scion Xa 2004 - 2007 0.31 60.2 66.7 23.4 7.26

So, my number is a little low -- or the official number is a little high?

[Daox]

That number is a calculation based on an average. Its unfortunately not an official number. If you can find one I'd gladly use it. The average is based on Hucho's findings that you can take length X width and multiply by .81 and come up with a good approximation. Actual measurement is likely much more accurate. I'll actually be updating that list real soon with some additional Saturn info.

I had also changed my formula back (I was using a different one) that was comming up with a greater frontal area. The new calculation shows your xA as 22.6 ft^2.

[NeilBlanchard]

Hi,

I'll try taking another photo with a longer lens; and I'll ask someone to run this photo through some corrective software, which can correct the perspective based on the specific lens and camera. (I'm using a Nikon D40x with the standard kit lens.) DataCAD is quite accurate -- it'll all come down to the polyline that I trace...

[NeilBlanchard]

Hiya,

An update on the first tankful with the Plexiglas rear wheel skirts -- they added ~1-1 1/2mpg, which is certainly something, but a bit less than I'd hoped. I got my best mileage so far -- 47.5mpg, which is ~0.8mpg better than my previous best tankful.

I will be getting a sheet of Coroplast on Monday (or so), so I will make a new version that cover up more of the wheel -- they will have to wedge out at the bottom to clear around the wheel. Maybe this will improve things some more?

After that, I'm going to try some metal foil tape on the alloy wheels (though this will not be able to cover more than half, due to the pattern and the location of the valve stem). And, I'm hoping to do something with the front wheels; just not full covers. And I'd like to finalize the upper grill block, and possibly do a partial lower grill block, too.

[NeilBlanchard]

Hi y'all,

Updating this thread: I've added AirTabs (pictures and results to come), and I've switched to Gorilla Tape for the grill block. The WeatherSeal tape is pretty strong, but it shirinks a lot, and needs full contact to stick well. It has been lifting off around the fog lights and the grill had been barely staying put; and it finally let go in the heavy rain we've been getting lately.

I got a sheet of dark blue Coroplast today! So, this weekend will be devoted to making some new wheel skirts out of it, that cover more of the wheel. I'm going to have to find some 5/32" metal rod to stiffen the lower edge; or should it be stiff enough on it's own?

[azraelswrd]

Nearly every skirt I've seen has a support bar at the bottom and at higher speeds or hot temps, that plastic is going to bend, warp and wobble. Guess it depends on how close they are to the tires/wheels.

[Xringer]

I think I've seen the 5/32" rod at Ace hardware in the dowel area.
Many hobby shops (RC Airplane etc) carry it too. Call ahead and save gas..

Nope, I also agree that coro is not going to be firm enough to hold it's shape
when under windloading.

If you were to use it to make some small air dams for the tires, it might be
stiff enough, if you put the corrugations going vertically.
(It's much harder to bend in that direction).

I've been thinking of making some for my tires, but can't decide on what size they should be.


This one only looks about 3" tall..?.

[NeilBlanchard]

Hi,

I go every Friday night to my local slot car track to race, and I'll check to see what he has in stock.

[NeilBlanchard]

Hi,

I've rebuilt the wheel skirts out of dark blue Coroplast -- I'm pleased with how they came out. Pictures soon, and data after that.

I'm not optimistic that the Airtabs are helping -- in fact, it seems like they are hurting my MPG. I don't know (yet) for sure, because it rained buckets (so I had to use A/C) and I've had four people in the car for much of my recent driving. But, after my commute to work this morning, I was only able to raise the average from 39.7 to 41.1mpg. Considering that I have averaged 45+ for the past 11 tankfuls, and my worst tank recently was 42+ -- I'm not holding my breath.

[NeilBlanchard]

Hi,

I've removed the AirTabs because they were hurting the MPG (by ~3mpg).

I also just removed the Gorilla tape from the "chin" -- I had used it to seal up the air vents, because I thought that if all the air went through the radiator, it would help. In fact, sealing it up hurt my MPG.

I have also done a partial block (covering about 2/3's) of the lower grill opening, and while I don't know if it is helping improve the MPG's yet -- but it is not hurting the temps! Not even a little bit...how much extra grill is there?