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Saw an EVO with the VG's and the Roof Vane today..


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Guest Vortekz

BTW I think the roof wing looks cool no doubt. And I would guess that if you increased the pressure of the air going by the VG's it may enhance the VG's effects.

 

I guess this one will be one for the next round of wind tunnel testing. I will pitch a bit in if we can do one test with no wing and make it a test car vs. same test car with VG's. I would also like to see this test done on a car with a flat roof.

 

Matt Dawson

www.vortekz.com

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Hey Matt.. sorry for this late response..

 

I didnt actually test the VG's or provide any of the data..

 

After reading the windtunnel results.. I decided to try them on my car.. I dont know who was the first to do em.. but here's my thread

 

http://forums.hybridz.org/showthread.php?t=122621

 

I am using your product and there is alot of info in this thread.. ALOT to read =)

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Not offering any answers here, but reminding everyone that, with the S30, it's not necessarily all about reducing drag, it's also about reducing lift as well. Those can be conflicting pursuits. Increasing drag can reduce lift, if applied in the right location. It just depends what result you're after. Seems the magic combination for the S30 would be something that reduces lift, yet dissipates that huge cloud of air a S30 hauls behind it everywhere. Just my thoughts.

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I need to clarify, at the back of the roof your wanting the air to continue to flow down the hatch and to the spoiler, right?

 

Like this on the back of the hatch to draw air downward.

 

http://cgi.ebay.com/ebaymotors/83-94-92-Chevy-S10-Blazer-4-3L-TBI-Rear-Spoiler-Wing_W0QQcmdZViewItemQQcategoryZ33638QQihZ016QQitemZ260168543846QQrdZ1QQsspagenameZWD1V

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I would suggest people get a hold of a couple of good books on the subject of aero if they are at all interested in it.

 

http://www.amazon.com/Competition-Car-Aerodynamics-practical-handbook/dp/1844252302/ref=pd_bbs_sr_1/103-3140541-9606231?ie=UTF8&s=books&qid=1192851260&sr=8-1

 

and

 

http://www.amazon.com/Race-Car-Aerodynamics-Engineering-Performance/dp/0837601428/ref=pd_bbs_2/103-3140541-9606231?ie=UTF8&s=books&qid=1192851260&sr=8-2

 

are both excellent.

 

FWIW IMNSHO, Matt Dawson is way off the money, and Jon is right on it.

 

Dave

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  • 4 weeks later...

as the air comes off the back of the roof, it tries to go straight.but it will also follow the body line if it slopes, as it does in the s30. so what ends up happening is it pulls up on the rear of the car unloading the tires. a spoiler counteracts that affect by redirecting the air back upward, thus pushing down on the car. the vg's on the otherhand (also known as turbulator strips) break up the air as it leaves the flat part of the roof, brealing this "suction" and making a even higher drag spoiler less/unnessicary. this is why cars like the lotus europa and vega kammback wagon came about, to get rid of the slope for aerodynamic purposes. hope this helps!

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as the air comes off the back of the roof, it tries to go straight.but it will also follow the body line if it slopes, as it does in the s30. so what ends up happening is it pulls up on the rear of the car unloading the tires. a spoiler counteracts that affect by redirecting the air back upward, thus pushing down on the car. the vg's on the otherhand (also known as turbulator strips) break up the air as it leaves the flat part of the roof, brealing this "suction" and making a even higher drag spoiler less/unnessicary. this is why cars like the lotus europa and vega kammback wagon came about, to get rid of the slope for aerodynamic purposes. hope this helps!

 

What? LoL

 

I think you know what your talking about.. just can't word it properly..

 

Vortex generators simply interfere with the boundary layer and create a turbulent airflow which "extends" that boundary layer. As long as the moving air "sticks" to the boundary layer, there will be no separation. The point of VG's is to delay the boundary separation.

 

In order to maximize the efficiency, the VG's are mounted as far back on the roof line, at the highest point (if possible) to re-direct the airflow separation towards the spoiler.

 

I dont believe VG's create lift.. just interference drag. As for the "roof vane" there is very very small induced lift (which unloads suspension not the tires). With induced lift comes drag.

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  • 3 weeks later...

I suppose some testing would be needed to figure it out for sure, but seems like someone is on a quest for more bling and figured if one is good than surely two is better...

 

I really hate to disagree with you jon, because i know you know plenty more than me, but my gut just doesn't let me let this comment pass/slide by.

 

Subaru and Mitsu have put more engineering work into the sti and evo than many companies put into entire platform lines. They get down right anal about the creation of these cars and their performance proves their work.

 

I'm no expert so I can't say for sure, but I'd be very surprised if the dual wing stock STI setup WASN'T for performance FIRST, and possibly looks second. And I'd be shocked if subie didn't do extensive testing like mitsu did with the VGs in making sure it works well.

 

 

Besides, have you seen how hideous the new STI is? How could they be doing anything for looks....

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I was praying I misunderstood something alone the way.

 

When was using both mentioned? I guess I might have found it so obvious you wouldn't use both that any mention of it might have gone completely unditected.

 

I'll go back and read the first few posts. Thanks for the clarification though jon.

 

Back to your regularly scheduled thread...

 

EDIT: You're right jon, the title of the thread clearly states... Geez, way to pay attention...

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I seem to remember that Mitsubishi did this test for us already. If you read the Mitsubishi paper on VG's iI want to say that it found that downforce did increase by just using the VG's, but the amount was so minimal that there really isn't any point. The idea is to get the air closer to the hatch so that when it hits the surface of the spoiler it has a greater effect, or in the case of a wing it keeps cleaner air hitting the wing.

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Does anyone know where the picture is of the Z-car in a wind tunnel with smoke going over it? I'm looking into these VGs and wanted to see the seperation happening to decide where to put the VGs. I know I have seen a pic of a car in a wind tunnel with smoke showing seperation and what not, I thought it was here in Hybridz. I think there might have even been a close up of the roofline/hatch area, giving a real good idea of where the air streams seperate up/back there. Just can't find the pic.

texis30O- Yes, with the VGs, your wing doesn't need to be as tall relative to the back of the hatch to catch a lot of air and cause a significant amount of downforce. The VGs make lower profile wings more effective, but I'm not sure how they affect tall wings (10" high and up). I would guess they would make them more effective too, but not quite as noticeably. Unless the VG's work so well that they pull the airstream real tight to the hatch/body. Then the bulk of the fast moving air might go under the tall wing, but I doubt this would be an issue, a tall wing sticking up into the air is gonna cause down force not matter what.

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  • 4 months later...

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