Remember that vid on Top Gear of the FQ400 against the Murcielago?

http://youtube.com/watch?v=s1ZWJjC648I

When the FQ400 was being reviewed, the vortex generator on it was referred to as a "hedgehog arrangement" (3:30min in). It appears to me that the fins are actually taller and larger than on the ones we get here. Just wondering if that's the case and if so, where can we buy the FQ version of the vortex generator?

 

this is not Best Motoring, it's Top Gear, a British car show

 

dude, it's the resolution of the video...have you noticed the car also appears taller than usual? lol

unfortunately, its the only video of the episode out there on the public domain that I'm aware of.

Why is this in "Evo Advanced"?

 

actually a while back..i saw in the JDM magazine...there were different design of vortex generator...

 

Does the vortex generator actually do anything?

 

yes

 

It's just hard to imagine that a tiny piece of plastic actually makes any difference....

 

yeah at like 150mph... but it still didnt stop me from getting one from rexspeed.

 

i works at lower speeds to. reduces the dynamic drag of the car. which raised the effectiveness of the wing and helps with gas mileage also.

 

I know, it breaks up the wind as it flow over the rear of the car and spoiler. just being stupid, sorry.

 

dont be sorry. i mainly liked mine on the mr because i thought it looked cool. and besides it makes people ask funny questions. especially the dumb females at drive threws

 

Hi all, this is my first post on EvoM so bare with me. Ive been lurking on these board for a while, saw this topic and felt it would be the perfect point to jump in. Just as background, i have a master degree in aerospace engineering with my focus on aerodynamics and fluid mechanics, so take my explination as you see fit. I dont know if this has been explained before, but here it goes, sorry if its long winded:

A vortex generator has been a secret tool of wind tunnel designers for a long time. As a rule of thumb, as low speed air (anything below Mach 0.8 or so) sees a divergent section, the angle of the divergence can only be around 7-8 degrees max before the boundary layer of the flow seperates creating turbulent, and thus unpredictable airflow. This relates to the back of a car since from the roofline down the rear window is a perfect example of a divergent cross sectional area. On a car, it is almost always greater than 7 degrees. In order to keep the flow attached to the walls at higher divergent angles, designers of wind tunnels employ vortex generators just before the divergence. What they do is purposly seperates the flow, creating a clockwise vortex. Now a turbulent vortex can be seen as a tiny swirlling vaccum that sucks in high momentum air. As the vortex gains this momentum, it forces itself back down against the wall, or in this case, the rear window. This allows designers to create divergent sections up to 13 degrees with attached boundary layers and thus laminar flow. Eventually the flow will seperate again creating turbulence, but at a lower plane then it would have before. Most people here say that it then redirects it over the wing. I wont speculate upon the purpose or affect of turbulent flow over a wing, so ill trust that mitsu did thier homework and its fine. Overall the affect of the VGs lower the Cd due to the delayed speration of the flow. In fact, the shape, and most importantly hieght, of the VGs are designed to be the exact height of the boundary layer at that location at some optimized speed. Meaning the aero engineers had to have picked a certain speed in order to optimize the VGs. Not saying they wont work at other speeds, but are most effective at, lets say, 60 mph. I will also speculate that the early seperation will allow for a greater rear vortex behind the car, otherwise known as the 'Kutta Condition.' This is important for reducing the overall drag of the car by creating suction on the front. But thats sort of a stretch.

 

it was carbon fiber...thats what i really want

 

welcome akyap. ur explanation is perfect. thanks for the long winded post. i sums everything up nicely. in words that i meant but u are better at stating.

 

Great post AkYap! That clears up some of the confusion! I just wonder what speed the VGs have been optimized to on the evos....?