Nice comb

[Megatron]

Very interesting approach to aerodynamic effenicy by Multimatic on the tail. Did you notice the "comb" design? What does this do to the air?

[RobweenerPI]

We don't like DP's round these parts stranger.

[Try Hard]

I'm not sure what you mean by comb, and i can't find any pictures of the rear end from this years rolex 24hr.
If you refering to the huge gurney on the back section of the bodywork, then it's a highly effective way of gaining more downforce for little drag.

From Dailysportcar.com's Technical section on the Multimatic Ford Focus
"It was found that this gurney had almost the exact same effect as the filled in space, and that they gained the same significant downforce with only a slight increase in drag. “Probably the most cost-effective improvement we’ve ever made,” Holt said."

Basically, the story goes that multimatic were looking for a downforce increase to counteract the lift being created by the fastback-shape body. Originally they tried filling in the channels either sde of the engine cover, effectivly raising the rear bodywork, but as they had already submitted a style for approval to GA (in which the channels weren't filled), they had to find another solutin, which is how the gurney appeared.
Hope it helps

BTW I personnaly find any kind of race car interesting, even if they do look butt ugly. The "We don't like DP's" line is a little sterotypical if you ask me. Just cause they don't look like we think they should, doesn't mean we shouldn't like them. After all it seems the people who matter (the drivers) do really like them!

Ed

[Aysedasi]

Originally posted by RobweenerPI
We don't like DP's round these parts stranger.

Well, they're still sportscars, no matter what some of us may think about them. So members are free to dicsuss them if they wish......

[Danske]

The #70 Multimatic modified their gurney to have comb-like teeth at the edge, like so: ^^^^^^^^^^. I'm not certain if they added or removed material to do that, though.

[Try Hard]

It's probably something to do with having vortices shed off the points, filling the hole behind the car better. But thats just my guess, based on a minimal amount of aero knowledge.

(on a different note, I remember seeing a similar thing on the surface of a McLaren F1 car's wing before, but in that application, as far as i understand, it had something to do with keeping the bondary layer conected to the wing for longer.)

[Danske]

#70 Multimatic (photo by Ken May for racingfanatics.com) Ah, there's the picture.

[blueflagger]

Maybe they are just cutting edges for duct tape repairs

Sorry, couldn't help the comment when I saw the picture; it's the first thing that came to mind.

[skycafe]

It makes it difficult for an errant dog to grab ahold and slow the car down?

[MulsanneMike]

Multimatic's aero guy seems to like the serrated gurney idea, bottom image:

http://www.mulsannescorner.com/panozlmp07-5.html

[blueflagger]

I guess I can see where it would act like a taller gurney if I imagine it in a wind tunnel. The trick would be in the angled edges changing the shape of the air flowing over them. The air flow would be pushed a bit higher. Twice as high? I'd want to see the colored smoke test. Admittedly though, I'm not an aero engineer so I'd better trust them.