Aero - Vortex Generators on an STi

[odysseyesm]

Spotted this today at the SA TA. It was on the Willall STi that Martin Donnen was driving.
Don't know where the idea came from but I reckon they (Willall) would have seen it somewhere on another Sti - prolly in Japan I'd say. I can't imagine Willal having enough cash to put the car in a windtunnel and see what they could come up wit - might have wool tufted it maybe... dunno.

With out reading up on it I'm pretty sure they do the opposite to a Gurney flap, in that it keeps the airflow going smoothly over the rest of the car due to the airflow disruption of the scoop and making the rear wing more effective.
If you look at passenger jets you'll see these all along the leading edge of the wing to make the flaps etc on the trailing edge more effective.
There's a few other things going on - but that's the gist to it.
http://i1038.photobucket.com/albums/a469/odysseyesm/IMG_1136-1.jpg

Edit: I just noticed the Pilatus sticker on the bonnet beside the VG's, if it's the Pilatus I'm thinking of they make aircraft. RFDS and the RAAF aerobatic team are Pilatus aircraft, maybe they've done something for them as a bit of a contra deal?

[0dd0ne]

95% chance they do fuck all or make the flow worse. same as the vortex generators people stick on the roof of the cars. even with the wool string you'd have no way of really seeing if they help etc and the tiniest movements make a difference in flow. that includes angle of attack. if you want them to look cool though, go nuts.

[Zadok]

I'm surprised they still keep the blue triangular stickers on the bonnet though, they clearly add unnecessary weight (not to mention wind resistance) that could be shed to make the car go faster!

[fauxpas]

The only reason they'd have them mounted there is to clean up (or attempt to keep clean) the air hitting the windscreen... Maybe at speed the wipers don't work properly or the wipers get buffeted... Or even an attempt to keep a nice waterspray pattern on the windscreen at a particular speed...

Either way they are the cheap vortex generators off ebay...

[lovecolt]

I say it MiGHT work.....but only as good as what the vortex generator is on the evo, which I believe only work when they are above 160-180 km/h. Guess it's no harm having in a racing condition as they weight nothing.

[Corosith]

My guess is that they are there to "disturb" the air just after the bonnet scoop to maybe create some pressure differences to make the cooling more efficient, can't imagine they'd bother with anything to do with windscreen wipers etc. (yes they are the cheap ebay ones).:)

[lovecolt]

My guess is that they are there to "disturb" the air just after the bonnet scoop to maybe create some pressure differences to make the cooling more efficient, can't imagine they'd bother with anything to do with windscreen wipers etc. (yes they are the cheap ebay ones).:)

But wouldn't it be placed before the top opening than after, if it's there to improve the cooling?

[Corosith]

Maybe so, just throwing ideas around. Another idea is that the bonnet scoop was creating a pocket of bad air, and the flow over the roof to the spoiler wasn't efficient as could be. The vortex generators would pull the airflow back down to the surface of the car so it runs straight and true over the top of the car. There is a vid on you tube showing something very similar with before and after shots with them fitted and not fitted (using stick on wind vanes to show the disruption/flow of the air). Willal Racing would have buckets of money considering the amount of hi-po cars the guy has had over the years and the amount of money spent on them, he also has a helicopter business and has owned every new GTR that has come out at the time.

[rokkuchan]

overall it's gay and just a cheap compulsive buy on ebay.

EDIT: meant to say 'impulsive'. but probably compulsive too

[alba]

overall it's gay and just a cheap compulsive buy on ebay.

this

the very definition of RICE

[fauxpas]

Just remember that vortex generators were invented to help keep airflow straight and clean for longer... They are placed on plane's wings where they found the airflow became dirty before the air passed the entire wing...

Their use on the evos is sound... They keep air coming off the roof clean at speed so it hits the boot wing cleanly giving downforce... Without them, the air gets turbulent and only some air will hit the wing as desired...

Whatever the intentions for use on that rex, there are some truths:

1. The generators will only affect air trailing them

2. They look ugly as sin on that bonnet and the rex owner needs terminating immediately

:)

[Kstiffy]

Lol probably to stop cats sleeping on his bonnet after its been run :p

[wombat]

That's Martin Donnon's STI.

I highly doubt Willal Racing would stick shit on the car if there wasn't an added benefit to doing it. These guys don't muck around, they're a serious racing outfit. Hardly 'Rice' in my opinion.

[oodLes]

LOL As if this fucking does anything on the bonnet.

[Macca]

they will work anywhere. as long as there is airflow.

The reason you place them somewhere is another story.

What Faux said is right.

they would work above that scoop maybe they were getting some turbulent air from it, but its worth in fixing stuff is far far less than how hideous it looks.

To be wanting the tiny tiny bit of down force they may aid in bt stopping turbulent air from the scoop.

[rokkuchan]

These guys have money, big deal if they have full outfit blah blah ... maybe if i stick them into my rear of my pants my fart gets better flow into peoples faces :D

[0dd0ne]

yeah go read about the ones on the evo. they are like a fraction of a cm off dead straight to make the air flow properly over the wing. they would have fucking spent hours workin it out in a wind tunnel. worth it? maybe on an F1 car. on the bonnet of an evo that likely wont get over 200km on any track, no.

[odysseyesm]

I'm going with Faux & Macca on the theory side.
I dunno wether they'd get much benefit at the speeds the car goes at on the track or the road. Coro saying that the dude owns choppers explains a bit. For mthe amount of gain Vs development costs I reckon they've copied it from somewhere. Either that or they just want to generate conversation from people about whatever Willall is doing ATM.

But then I made up a 20mm Gurney flap using some tile edging from bunnings and stuck on the stock rear wing with double sided tape. I think it works quite well at tightening up the back end at higher speeds (+80klms).
Only cost me $8 all up, I'm sure plenty of people will think it's bullshit but I'm going to leave it there. It basically looks like the one on the rear wing of Ken Block's Fiesta.
http://www.flickr.com/photos/aipsensmall/5208725106/
Not as high though.

[fauxpas]

Wanna know if they work on the Evos? Check this youtube vid out...

Also, has anyone thought of asking the rex's ownder/builder why they are there?


http://www.youtube.com/watch?v=DlXiRoIqGpU

[wombat]

Maybe we should get Donnon off the evo gsr forum to explain the deal with it?

[kalt]

What if the vortex generators were placed inside the bonnet scoop in a row, and maybe possibly fit a shark fin antenna on the roof.... then would it look more like a predator??? ;)