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Discussion Starter #1
Black & Gold in So. Cal.

My 02 WRX seemed to get bounced around quite a bit in strong wind at speed. The STi is much more stable. Could it be the wing? I'm talking around 75 mph.

Jim
 

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I noticed the same thing. Right around 75-85. You had to fight it a little to keep it straight at that speed. I noticed my STI doesnt do that.
 

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Comparing a wingless WRX to a winged STi doesn't tell you anything about the wing. We all know there are many suspension diffs. between the two. The only way to tell would be to put a wing on your WRX and feel for the diff. Or take the wing off the STi and check it out. There are a few swaps around. I'm curious to know...I'm thinking of swapping and going wingless on my STi.
 

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He didnt say it was the wing, he said it could be the wing. All I know is my STI doesnt get blown around in the wind like my wingless regular wrx did.
 

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Oh boy....we need to sticky this type of thread.

In a nutshell, our wing is functional. It doesn't create downforce per say, but it instead decreases the amount of lift created on the rear of the car that would otherwise be created by the turbulence of the flow that separates from the rear window.
 

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Discussion Starter #7
I think what Rob said makes sense, plus the uprights on the sides of the wing probably act as vertical stabilizers like an airplane.

I don't s'pose any WRX owners with STi wings read this forum much, would be interesting. to hear from them on the subject.

Jim
 

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YES, it does work.

the top fin actually directs air to go under the fin, to direct airflow to the bottom flush piece of the spoiler creates the downforce.

downforce is also created by the tall "fences", the high sides of the spoiler. In spoiler design on race cars, notice that a lot of them have high wings, a center mount, but long fences hang downwards. Thats why none of the ricer crap from APR work... none of them have long fences.. they all think that the multiple horizontal fins aimed aggressively is all you need...

also on the STi wing, it smoothens the turbulence created by the pressure coming out from under the car, over the car, and through the spoiler.... i know it does that, but i dont know to what extent. Most likely not very effective since the WRX impreza has all these fins in it now...
 

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Not quite, but at least we agree on the 'it works' part.

If we were to take the top part of the spoiler off, it would take away all positive effects of the rear wing. Small wings, such as the stock WRX wing, do nothing for downforce. The profile of the Impreza puts it in the box cabin type, which are known to cause flow separation beginning at the top of the rear window which creates a turbulence zone that doesn't end until the air has left the rear deck of the car. This means that the only air most little spoilers (WRX stocker) catch is turbulent air, which will do nothing to combat the lift effects caused by the turbulence air.

The top section is high enough that it is in the laminar flow that continues to come off the top of the car. By putting that surface in the laminar flow, the top part of the wing negates the effects of the turbulent lift created below it. It isn't creating downforce, it isn't directing air anywhere...it's just sitting up in the clean air keeping the rear end from feeling the lift.

The fences on the side....not of a great deal of help in this case. When you get into actually aerodynamically designed rear wings (see WRC, F1), they care about the air escaping off the sides of the airfoil once it has hit it. Obviously if air is spilling off of the wing, it isn't creating the lift that it should. Since our wing doesn't actually create downforce, this really shouldn't apply much at all.

Smoothing flow at the rear of the car.....I don't think any wing does that. You just created a giant hole in the air with the car....there is going to be a mad rush of air behind the car unless you taper the rear of the car down like a race biker's helmet. Again, you can kind of see this thought in the rear design of F1 cars....they start to flare back in. The Impreza...most certainly does not.

There is a great write up out there somewhere that has detailed discussions about this as well as road tests showing the airflows around different cab types, wing types, you name it......
 

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Hey Rob,

If you've got that link handy I'd love to check it out. Maybe we could get some CFD's done on the car to make those oh so pretty pictures :)
 

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It was on NASIOC somewhere. I know it was linked to from a 'wing' thread in the old STi forum.....I don't have the time right now but if I get the chance I'll go hunting.
 

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Buy now... or wait?

Fhqwhgads said:
Hey Rob,

If you've got that link handy I'd love to check it out. Maybe we could get some CFD's done on the car to make those oh so pretty pictures :)
CFD would look rather nasty for the flow on the back of the car (a lot of turbulent, re-circulating flow) :) there certainly would be a lot of colors in the pictures :p
 

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think this is the most convinving thread so far and I have put my plan to dewing my car on hold.

http://forums.nasioc.com/forums/showthread.php?s=&threadid=398276&highlight=STi+wing+FAQ

Would still like to do it - but until I have found good plugs for the holes and enough funds to get the inside 3rd brakelight.

May even consider masking the wing black so at least it does not stand out so much at night. But black wing on a silver STi may not be my cup of tea.

I'll worry about the winter wheel/tyres first for now.

Chif
 

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matadorCE said:
CFD would look rather nasty for the flow on the back of the car (a lot of turbulent, re-circulating flow) :) there certainly would be a lot of colors in the pictures :p
Lots of colors is what I want to see :) Sure would make a nice background

I was figuring with the rather sharp windshield and sharp drop in the back it would happen.
 
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