 Aerodynamic Question, Front Wheel Wells high or low pressure? |
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| race914 |
 Mar 14 2006, 02:16 PM
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#1
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73 914-4  Group: Members Posts: 1,006 Joined: 31-October 05 From: Nipomo, California (Central Coast) Member No.: 5,027 Region Association: Central California  |
I was watching a special on last years ALMS series at Sebring, and during a pit stop for the Corvette team, you could see the light coming through the front wheel well vents onto the tire.
I had always assumed the vents like on the Corvette C6.R and/or Porsche 935s were to equalize high pressure built up in the wheel well. Then I recalled the Oil Cooler - Round 2 thread noted that the front wheel wells are a low pressure area. Can anyone help out? Attached image(s) 
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| ArtechnikA |
Mar 14 2006, 02:24 PM
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#2
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rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
it's all relative...
yes, the upper-fender vents (or the aft-fender vents on the RSR's) are to vent the nose and prevent lift. yes, the wheel wells are low-pressure areas - relative to the front of the spoiler (oil cooler air inlet). and if the oil cooler is venting into the fenderwell, along with the brake heat, anything you can do to get the hot air out is A Good Thing. which is yet another reason 935's ran with wheel turbines on their BBS wheels... |
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| race914 |
Mar 14 2006, 03:27 PM
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#3
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73 914-4 Group: Members Posts: 1,006 Joined: 31-October 05 From: Nipomo, California (Central Coast) Member No.: 5,027 Region Association: Central California |
Thanks for the reply and putting the 'low pressure' comment in the 'oil cooler' thread into context. I wasn't looking at it from the right point of view.
Your right about everything being relative. My financial advisor told me it's easy to make a small fortune day trading stocks.... You just need to start with a large fortune! |
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| TimT |
Mar 14 2006, 04:01 PM
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#4
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retired Group: Members Posts: 4,033 Joined: 18-February 03 From: Wantagh, NY Member No.: 313 |
Here is some info from Porsche wind tunnel testing.
Attached image(s) 
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| East coaster |
Mar 14 2006, 04:06 PM
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#5
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Senior Member Group: Members Posts: 1,668 Joined: 28-March 03 From: Brigantine, NJ Member No.: 487 Region Association: None 
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Wow............facts are cool !!
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| race914 |
Mar 14 2006, 04:11 PM
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#6
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73 914-4 Group: Members Posts: 1,006 Joined: 31-October 05 From: Nipomo, California (Central Coast) Member No.: 5,027 Region Association: Central California |
Great diagram showing the difference in low pressure areas with & without louvres.
And again I had it backwards, the end objective of the vents are to negate the low pressure areas going over the car, not to 'release' the high pressure in the wheel wells... Learn something every day! What is the source document for the Porsche Wind Tunnel testing info? |
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| Brett W |
Mar 14 2006, 04:12 PM
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#7
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Advanced Member Group: Members Posts: 2,856 Joined: 17-September 03 From: huntsville, al Member No.: 1,169 Region Association: None
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Tim
Where did that info come from? |
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| Terrance |
Mar 14 2006, 04:15 PM
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#8
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Member Group: Members Posts: 125 Joined: 2-August 05 From: Milpitas, CA Member No.: 4,526 |
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| TimT |
Mar 14 2006, 04:18 PM
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#9
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retired Group: Members Posts: 4,033 Joined: 18-February 03 From: Wantagh, NY Member No.: 313 |
Another set of figures from testing the 936, in this case the louvers are taped,up and drag decreases, and front lift increases.
Attached image(s) 
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| TimT |
Mar 14 2006, 04:20 PM
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#10
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retired Group: Members Posts: 4,033 Joined: 18-February 03 From: Wantagh, NY Member No.: 313 |
The info I scanned is from a book "Porsche racing cars of the 70's"
By Paul Frere Mulsannes Corner has some great areo info also.. I had forgotten about that site. |
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| race914 |
Mar 14 2006, 04:31 PM
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#11
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73 914-4 Group: Members Posts: 1,006 Joined: 31-October 05 From: Nipomo, California (Central Coast) Member No.: 5,027 Region Association: Central California |
Thanks Guys... Great info.
I just ordered: Race Car Aerodynamics: Designing for Speed and Competition Car Downforce |
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| TimT |
Mar 14 2006, 04:38 PM
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#12
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retired Group: Members Posts: 4,033 Joined: 18-February 03 From: Wantagh, NY Member No.: 313 |
I have both those books, they are very handy and informative. Im not sure if Freres book is still being published
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| lapuwali |
Mar 14 2006, 04:45 PM
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#13
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743  |
Frere's book is out of print, but Barnes & Noble can order it used through their network. Just snagged a copy.
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| Air_Cooled_Nut |
Mar 14 2006, 11:52 PM
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#14
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914 Ronin - 914 owner who lost his 914club.com Group: Members Posts: 1,748 Joined: 19-April 03 From: Beaverton, Oregon Member No.: 584 Region Association: None |
There's this as well:
http://www.icbm.org/cmgallery/displayimage...?album=23&pos=5 |
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| race914 |
Mar 15 2006, 08:50 AM
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#15
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73 914-4 Group: Members Posts: 1,006 Joined: 31-October 05 From: Nipomo, California (Central Coast) Member No.: 5,027 Region Association: Central California |
Another good diagram! Gives a good visual on why the 935 front fender louvre placement is slightly ahead of the tire's verticle center. Anyone done front wheel well louvres on their 914? Got any pics? |
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