Porsche 911 GT3 RS

[aerohead]

Originally Posted by serialk11r

The roof fins caught my attention. I wonder what they do. The standard 911 body should have fully attached airflow and minimal trailing vortices over the rear.

I agree about the roofline. By 1993, Porsche had taken 6-degrees of slope out of the 911's rear since it debuted in 1965. Water-cooled, and with a front radiator, it no longer relied on separation-induced downwash to get cooling air.

The black car shown does not have the fences, only the white car.
I've driven the old 911 S on dirt roads in West Texas. It WILL oversteer, although judicious use of the throttle makes for uneventful power-steer 'drifting' and big smiles.
On a wet race course, and at speed, should one loose traction, and over-rotate, the roof fences would kill some unwanted induced lift, and perhaps allow the owner to race another day.

[Leinaad]

Originally Posted by serialk11r

The roof fins caught my attention. I wonder what they do. The standard 911 body should have fully attached airflow and minimal trailing vortices over the rear.

There was an explanation for that in a different video.
I don´t fully remember but it´s to ensure the engine intake gets cool air. They placed the water cooler in the trunk like in the race cars and redirect the hot air to the sides so it doesn´t flow over the roof into the air intake.

[freebeard]

It's in this video about the 5 minute mark. The fins work together with the new radiator outlet. to manage the radiator outflow.