XDEEDUBBX

they are already made in cf.. Look on ebay.. Haha

Wolverine

Since I am the first with them. I'm sure that Mitsubishi and Subaru designers are just a bunch of idiots that don't know nothing about aerodynamics and should listen to all you experts sitting at home. Here's a photo for all you playa haters.....

rx8spiritR

i actually think they look nice..................
at least better than some huge trunk spoiler

WreakLoosE

Maybe they work well for the Mitsubishi and the STI not RX8 or Mazda may have thought to put them on as well. Aero Dynamics was a huge design consept for the 8. Both the Evo and WRX use them because both cars are three-box sedans - and it's this shape which often has a lot of aerodynamic problems. A small wake behind the car (ie leaving only a small amount of disturbed air) will usually reduce drag. Cars with sloping tails can achieve airflow that remains attached right to the trailing edge, but that's often not the case for booted sedans. Instead, on these cars, the flow often separates on the rear window, which is bad news for drag reduction. Vortex Geerators and Roof Spoilers Help keep the air flow attached better to the rear of the vehicle and provide better aero dynamic flow for that type of sedan. The 8 has more of a sloped design so the air does not separate nearly as much as the evo and wrx. So the Generators will do little to no good at all. And in some cases even cause more drag on sloped type vehicles. So Wolverie you are right the Aerodynamic Engineers for Mitsubishi and Subaru knew what they where doing for the type of car they where working on.

Wolverine

Here's an unbiased report on vortex generators....

http://autospeed.com.au/cms/A_3058/article.html

http://autospeed.com.au/cms/A_3059/article.html

http://autospeed.com.au/cms/A_3060/article.html

http://autospeed.com.au/cms/A_3061/article.html

Wolverine

If I hadn't already placed the vortex generators, I could do the wool tuft test. Unfortunately I do not know anybody else who owns an RX-8 in my area.

Wolverine

Maybe we could ask Adam and Jaime of Mythbusters to do the test for us. They already proved that tailgate up is more aerodynamically efficient than tailgate down.

WreakLoosE

That was the same Article I just looked at. To make sure I was telling you the correct stuff. They work for the correct application. I just think the RX8 will show no benefit from it because the Rear of the car slope is smoother than the EVO. So not much Turbulence is created and the aerodynamic Boundry layer is a lot closer to the car than that of the Evo. Oh yes. for the VG's to even work properly for the vehicle. We would need to know the thickness of the boundry layer in the back of the vehicle. If the VG's are too tall they create too much drag and cause a problem. They also need to be the correct height for the particular boundry layer the 8 makes. A rule of thumb is that the height of the vortex generators should not be much greater than the thickness of the boundary layer. So for them to even have a chance to work correctly for the car you would need to know where the boundry layer begins on the 8. That small detail makes it a bit harder to have universal VG's

Oh yes tailgate up is better. Because of the locked vortex flow, or separated Bubble for pickups was the reason why they are more aerodynamicly better with the tail gate up rather than it down. The air flow falls back on the tailgate when it is down causing drag. When it is up. The locked vortex flow allows the air to pass over the truck bed completly with less drag. in a nutshell with a up tailgate, a lower moving (sort of pillow of air) would flow in the bed and the passing air would go over it. When the tail gate is down this breaks up that pillow and the passing air makes more drag on the vehicle.

I think I heard of myth busters doing a test of this type.

sorry for whatever typos in this post i am tired.

Wolverine

Yes, I do understand what you and the article means. The flow separation, the amount of angle(the slope) between the roof and the rear window is much more severe on the Evo MR than on an RX-8. Nevertheless, the RX-8 does still have a slope. A lesser slope at that, as you can see on the Mazdaspeed RX-8 in my sig. Until we can do a wool tuft test, we cannot yet cofirm, say it's plausible, or say it's busted. On the next episode of Mythbusters!....

Wolverine

BTW. Look at the slope of the [TURBO????] Toyota Prius. It is very similar to the RX-8.

WreakLoosE

Yea it may be similar angle but the curvature of the 8 window is another thing. and may also be smaler than the Prius Turbo??? and reduce that issue. But like you said it may be plausible. We cannot bust for sure unless it is tested. I think I may try some Tufting testing today to see if VG's are needed on the 8.

Jethro Tull

iTrader: (6)

I used to design aerodynamic structures in a previous life...this thread has been amusing. Yes, the "vortex generators" can have a positive effect on drag reduction (if located properly) but there are so many other areas to clean-up on even the most slippery car, that they don't make much difference all on their own and at typical highway speeds. It's "drop in the bucket" time. WreakLoosE has been aluding to this while trying to be polite.

nordichunter

would it make more of a difference if the vgs were put on the trunk as opposed to the edge of the roof line?

Spin9k

Ok then here's a ? for you. I'm not caring about reducing drag at 'highway speeds'; I'm caring about reducing drag at 'as fast as I can possibly go speeds'.

At just what speed do you think it DOES make a measureable difference? 100mph..120mpg... 200mph? Thanks for your expert opinion!

nordichunter

some more VGs.... @ airtab.com

daisuke

A buddy of mine bought the fuel line magnets off of ebay... what a tard... he should buy these too "wow... if the evo has them they must work!"