Scion xA aero mods

[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?