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Old 05-24-2012, 07:36 PM   #1 (permalink)
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Neon Aeromod coastdown testing Results

Hello everyone, sorry I don't post very often, I mostly just hang back and read, but my turn to contribute a bit, and hopefully get some feedback.

My car is a 2000 Dodge Neon, which you can see what I've done here:

http://ecomodder.com/forum/showthrea...ods-20741.html

For testing, I did 120-70 km/h coastdown testing, the road was not totally flat (none in southern Ontario are), but I figured that since I am only using it for comparison sake it should be okay since it is consistent. A friend of mine started and stopped the stopwatch, and didn't tell me any numbers during the testing just to try and keep this is objective as possible.

Anyways, my new mods that I tested were a vertical (Nascar style) spoiler at the very back of the car, which extended vertically above the trunk lid. Although it was not quite meeting up with the template line, I didn't want to go higher due to visibility concerns and also lack of material.





On it's own, this spoiler had an increase in drag of 4.3%. However when tested with version 1 of the kammback (see below), it was only a 3.4% increase in drag. In the pursuit of gas mileage, it is needless to say that this spoiler did not stay on long.

Next was my "bonneville" style spoiler. Which extended straight off the back of the trunklid. For this, I only went back about 6" because this allowed the back of the spoiler to be flush with the rear bumper, the final version will most likely extend a little bit farther out.



I would also greatly appreciate any input as to whether I should try an upward or downward slope to it, as well as any comments about overall length.

After doing some reading, I understand that going upwards with it could be beneficial to help it reach the template line, although sloping it down could reduce drag farther if it's long enough. I wanted to test these but I ran out of time.

Based on the coastdown testing, this spoiler alone gave a decrease in drag of 3.9%.

Tested with version 2 of the kammback gave a total of 7.1% decrease in drag (compared to only 4.56% drag reduction from kammback alone)

Here is the partial kammback, sorry I only have pictures of version 1. It got too dark by the time I revised it for any decent pictures. It will be going back on the car and can get updated pictures if you would like. I built it as you see for visibility, trunk access and the length was because that was how big of a piece of coroplast I had leftover.
Here it is:





If someone would mind double checking my angle, it would be a huge help, thank you!


This first version of the kammback, I know that I made the sides taper in too quickly, which was made a bit better in the second version, which I added 4" to it, allowing the side pieces to attach a better angle. I measured it to be 21*, so still too sharp, but better than before, and better than stock.

The first version of the kammback had an improvement of only 3.1% drag reduction, and the second (revised) version had a total drag reduction of 4.56%. I think that if I make it a bit longer, and keep working on the side angles I can get a little more from it.

So there we are, I still have a ways to go yet but this at least gives a good starting point, and some numbers for comparison as I revise these mods and keep testing.

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Old 05-24-2012, 08:14 PM   #2 (permalink)
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If anyone has any questions or comments I am open to feedback, Im sure that you guys know a LOT more than me.
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Old 05-24-2012, 08:21 PM   #3 (permalink)
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i've been considering a bonneville style spoiler myself, i didnt even consider the idea of sloping down, kicked around the idea of sloping up, but am thinking that i would try something flat. which when i thought about it, thats how they do it at bonneville, so it kinda made sense. likewise with the length, i think what you see on the cars at bonneville might be the best for aero, but i think at that length and limited profile (hard to see at certain angles) i could see issues arise in parking lots, backed into, walked into, door opened into, so i dont think i would extend it very far past the edge of the bumper.
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Old 05-24-2012, 08:25 PM   #4 (permalink)
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Thats exactly what I was thinking too, if I go past the rear bumper, it wont be much mlre than 1" or so, Luckily the neon bumper extends quite far out from the edge of the trunklid.
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Old 05-24-2012, 08:27 PM   #5 (permalink)
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I should mention, my bonneville spoiler has metal rod beneath the cardboard giving it strength, it did not flap at all.
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Old 05-24-2012, 08:34 PM   #6 (permalink)
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yea, i'm interested to see how your later versions are made / attached / look also... so i can copy it
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Old 05-24-2012, 08:43 PM   #7 (permalink)
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I have some aluminum sheet that I can use, although it is a very thin gauge so a frame of some sort will be necessary. As for attachment, since this car is very rough already, I might just bolt it on through the trunk lid, although Im debating some other mounting options.
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Old 05-24-2012, 08:49 PM   #8 (permalink)
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2000neon -

I'll let others chime in, but here is my overlay :



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Old 05-24-2012, 08:51 PM   #9 (permalink)
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guess i'd probably go with bolts or something simmilar too ,since i'd be replacing my stock spoiler and already have holes. alum. sheet plays on my parking lot issues, if you could do a rolled edge might give it strength, while making it less of a blade to passers by.
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Old 05-24-2012, 08:56 PM   #10 (permalink)
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Thanks cfg!

As for the aluminum, i did some of my belly pan with the aluminum around my exhaust, I did a double "factory fold" on the edges, it was amazing how much of a difference in strength it made. I might even do a piece of roundbar along the edge of it, although that adds more attachment problems, lol.

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