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


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didnt have a chance to snap some pics but it looked surprisingly good!

 

 

The combo with Vortex Generators with Subaru's roof vane introduced in the 2007 models... and the EVO wing looks amazing.

 

I cant imagine how much drag that cleaned up.

 

If anyone hasnt seen the roof vane it looks like this

subaru_roofspoiler_1.jpg

 

and this are VG's on an EVO

eg-sp-rr-evo8-2.jpg

 

 

Too bad the roof vanes are like $130 on ebay.. damn!

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I wonder if those two devices work well in conjunction with each other. My instinct tells me no, because either you're creating vortices and then trying to steer them, or you're steering the air so that it's stays attached to the rear window and then creating vortices which would lessen the pressure on the rear window.

 

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...

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Geez, if that's the same 'Buffum' that was running a TR7 in the 76 POR WRC Rally, then yeah...I'd agree that photo was old! LOL

 

(Same guy got more noteriety driving RX7's and an Audi Quattro later in his career!)

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  • 2 weeks later...
Guest Vortekz

Hi all this is Matt Dawson from Vortekz.com glad to see you guys are talking about the VG's.

 

Proxlamus, I have been trying to get in touch with you. I saw your post about wind tunnel testing on Zcar.com I posted a reply but the post was so old I don't think anyone saw it. In that post you mentioned you had the results from your aero testing but I could not find a link to the info. I would love to see it. Please email it to me at service@vortekz.com or post a link if you have it up online.

 

Someone on another board brought up the Subaru roof vane. They said that the vane did the same thing as the VG’s here was my response.

 

The Subaru WRX sti roof wing does the same thing. That could not be further from the truth. That wing may increase aero drag by creating more slow moving turbulent air flow off the rear end and create up force in the middle of the car. Also it slows the air down before sending it under the rear wing (all be it it is going faster under the rear wing than it would without it but it is still slowing the air down vs. VG's). Also it may in fact decrease the effect of the rear wing because of the turbulence that it creates. VG's actually help speed the air not by pushing fast air through the slow air but by sucking the slow air into a number of fast moving vortexes increasing its speed and pressure. The slow air pulls or sucks the vortexes down and that is why the vortex generators decrease drag. So in reality the roof vane may actually increase drag and turbulence both bad.

 

My 2 cents.

 

Matt Dawson

www.Vortekz.com

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Hi all this is Matt Dawson from Vortekz.com glad to see you guys are talking about the VG's.

 

Proxlamus, I have been trying to get in touch with you. I saw your post about wind tunnel testing on Zcar.com I posted a reply but the post was so old I don't think anyone saw it. In that post you mentioned you had the results from your aero testing but I could not find a link to the info. I would love to see it. Please email it to me at service@vortekz.com or post a link if you have it up online.

 

Someone on another board brought up the Subaru roof vane. They said that the vane did the same thing as the VG’s here was my response.

 

The Subaru WRX sti roof wing does the same thing. That could not be further from the truth. That wing increases aero drag by creating more slow moving turbulent air flow off the rear end and creates up force in the middle of the car. Also it slows the air down before sending it under the rear wing (all be it it is going faster under the rear wing than it would without it but it is still slowing the air down vs. VG's). Also it may in fact decrease the effect of the rear wing because of the turbulence that it creates. VG's actually help speed the air not by pushing fast air through the slow air but by sucking the slow air into a number of fast moving vortexes increasing its speed and pressure. The slow air pulls or sucks the vortexes down and that is why the vortex generators decrease drag. So in reality the roof vane may actually increase drag and turbulence both bad.

 

My 2 cents.

 

Matt Dawson

www.Vortekz.com

 

Thanks for the insight Matt, Its great that you came over here and checking out the products and how they are working on our older cars. I hope you stick around.

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I don't think Matt is right about the function of the wing/deflector/whatever you want to call it on the Subaru. The idea is the same, to get the air to more closely follow the body line of the car reducing the size of the turbulent wake drag which sits behind the rear glass. They are just two different ways of accomplishing the same goal. The effect on the wing is the same in that they direct the air down to follow the body line of the car and hence into the wing directly. The effect on drag might be minimally different, in that the vortex generators each produce a small amount of drag, and the deflector also produces drag, but is a larger piece. The deflector might produce less drag or more drag, haven't seen any testing either way.

 

Vortekz, see post #14 here for a windtunnel test showing the effect of the two devices: http://forums.hybridz.org/showthread.php?t=117165

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Guest Vortekz

I just noticed the wind tunnel test data posted by Mikelly. I DLed the pdf from Nissan Sport. It is going to take me a long time to digest that.

 

I don't see a test with the same exact specs with and without the VG's am I mistaken or is ther one? I would love to see what the VG's alone did to drag. I know you guys just wana see if they can help that rear end stick : ) and it looks like they did. But I would love to see what they did with drag for a car with no wing then I could start selling to all the mpg. guys as well.

 

I was thinking the other day and thought of a good point let me know your opinions.

 

In the Evo papers you will notice both the VG aero tests are done with the wing. The #'s they are comparing this to are without the VG's but still with the wing. If the wing adds and additional 15lb down force w/VG's at the speed they are testing and still reduces overall aero drag even by a smidgen then without the wing the decrees in drag #'s would shoot through the roof. I mean think of this, how many lbs of drag does it take to create 15lbs of new down force (seems it would be much more than 15lbs.) and they still reduce overall aero drag on the car.

 

Any thoughts guys?

 

Matt Dawson

www.Vortekz.com

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It's not about what ONE component does to the drag. It's about the total drag. What I mean is if you put the vortex generator in the wind tunnel, it's going to generate drag. No question about it. But if it reduces the wake drag, you may end up with an overall drag reduction.

 

The vortex generators were not tested alone to determine their effect on drag. But you can buy VG's for semis specifically for that purpose, this too was discussed in one of the older threads before the testing was actually done. I have no doubt that the VG's reduce drag in the end. But they increase drag in their immediate vicinity, as shown by the Mitsubishi paper in pics 11 and 12: http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/2004/16E_03.pdf#search=%22vortex%20generators%22

 

There is also this quote:

However, negative pressure region around the VGs indicate that the VGs themselves cause drag
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Guest Vortekz

jm that is great info, I went and looked at the post and my preliminary observations are this. It seems this test was done without VG's on the Mitsu. I cannot really tell what the roof wing has done. If the roof wing had worked wouldn't the smoke be shot under the roof wing and rear wing?

 

Mitsu put the VG’s 100MM before the air flow separation while Subaru places the wing after the air separates from the roof and in that image actually looks to be even with the roof line.

 

Matt Dawson

www.Vortekz.com

 

P.S. Not an engineer

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Guest Vortekz
It's not about what ONE component does to the drag. It's about the total drag. What I mean is if you put the vortex generator in the wind tunnel, it's going to generate drag. No question about it. But if it reduces the wake drag, you may end up with an overall drag reduction.

 

The vortex generators were not tested alone to determine their effect on drag. But you can buy VG's for semis specifically for that purpose, this too was discussed in one of the older threads before the testing was actually done. I have no doubt that the VG's reduce drag in the end. But they increase drag in their immediate vicinity, as shown by the Mitsubishi paper in pics 11 and 12: http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/2004/16E_03.pdf#search=%22vortex%20generators%22

 

There is also this quote:

 

Yes I understand that, I got off topic with the gas saving aspect, but what I am saying is if you add the huge increase in drag from the rear wing + the slight increase in drag from the VG's you still get less overall drag. If you take away the rear wing will that not lower the drag by leaps and bounds (relatively)?

 

If that is the case then that is good info for people trying to save a few bucks a year on gas.

 

Matt Dawson

www.Vortekz.com

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I don't know the answer to your questions. I am not sure if that is just a crappy pic or if they compared the non VG'd Evo to the Subaru. I think you'd have to have a before and after pic for both setups to really be able to compare the effectiveness of one to the other. Right now we're just guessing.

 

I'm not an engineer either, by the way.

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