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Aerodynamic issue?

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Old 04-16-2012, 12:40 PM
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tmg57
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Default Aerodynamic issue?

It's been reported on another 991 forum that people are experiencing very annoying wind "buffeting" when driving with the windows down and the sunroof closed starting at about 85MPH. A couple of owners who have reached speeds of 120+ at the track report that it becomes almost unbearable, even with a helmet. I am wondering if any 991 owners on this forum have any comment?
Old 04-16-2012, 01:17 PM
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chance
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yep. noticed that very first day of highway driving. don't have a sunroof, for me windows down a requirement–very annoying.
Old 04-16-2012, 01:35 PM
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frayed
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Well that sucks. Does that mean you need a sunroof for track driving or you'll go batschit crazy with buffeting? Even that's difficult b/c most DEs dont want to see your sunroof open.

What if the passenger window is just cracked open and the driver's all the way down?
Old 04-16-2012, 01:47 PM
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97c2s993
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Originally Posted by frayed
Well that sucks.
What if the passenger window is just cracked open and the driver's all the way down?
I agree, this totally sucks. That said, I only noticed the buffeting with just the driver's window down. This is solved by slightly cracking the passenger window, and doesn't require the sunroof to be open. Have the same issue in my 993...
Old 04-16-2012, 05:46 PM
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frayed
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OK, thanks. No biggie then.
Old 04-16-2012, 10:43 PM
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Ed Burdell
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Originally Posted by 97c2s993
I ...Have the same issue in my 993...
Never noticed. I'll have to try it and see now.
Old 04-16-2012, 11:31 PM
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SSST
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Well the 996tt cab does not buffet at 140 with the top down. Don't ask me how I know.
Old 04-17-2012, 01:58 AM
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C DeVito
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Same with every 911 I've even owned. Always need to crack the passenger window or roof at highway speeds.
Old 04-17-2012, 08:23 AM
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tmg57
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Just to clarify, the posters on the other forum claimed that the problem exists with BOTH windows all the way down. As frayed pointed out (above), this can become a problem at track events where there is windows down requirement.

I think that one of the guys from the other forum posts here. Maybe he will chime in.
Old 04-17-2012, 12:10 PM
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jcf7
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Originally Posted by 97c2s993
I agree, this totally sucks. That said, I only noticed the buffeting with just the driver's window down. This is solved by slightly cracking the passenger window, and doesn't require the sunroof to be open. Have the same issue in my 993...
Same for me.
Old 04-17-2012, 12:55 PM
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jumper5836
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Is it the roof liner that is the cause?
Old 04-17-2012, 01:01 PM
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frayed
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The buffeting is like a standing wave and many cars do it. Heck, my Tundra does it when the rear windows are down but fronts up. Maybe some enterprising armchair engineer can come up with a deflector to prevent the buffeting. Shouldn't take much.
Old 04-17-2012, 06:05 PM
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930man
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oh it is an issue!!!!!! was the first thing i noticed.. I raised the passenger window about inch and it was better... it was loud at 145!!!!!!
Old 04-17-2012, 06:06 PM
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930man
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Originally Posted by jumper5836
Is it the roof liner that is the cause?
turbulence off rear window
Old 04-19-2012, 11:43 AM
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Scott997
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Originally Posted by 930man
oh it is an issue!!!!!! was the first thing i noticed.. I raised the passenger window about inch and it was better... it was loud at 145!!!!!!
Downright violent! I hope its not an issue in the next GT3. In the US on tracks we drive with the windows down. In Europe they drive with the windows up. The car is amazing in every other way. I'll try finding that sweet spot with the window up just a tad.


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