want a better controlled feel at high speeds
#31
07-11-2008, 11:37 AM
I have H & R springs only installed on my 2003 tiptronic.. lowered the car to a height I love... but I feel at high speeds the car feels light in the front end.. steering feels light.. not solid feeling.. could that be from the springs? I also have new tires all around.. alignment was done with tires... would different shocks help me ride? do I need to remove the H & R springs and start over? car is only driven on the street.. no track use..
thanks
thanks
yeah i was nervous about this too when i installed my spring but car feels dead stable....189+
#32
07-11-2008, 06:23 PM
[media]http://www.youtube.com/watch?v=y65oUlBMSUs[/media]
Great discussion Jean-
#33
07-11-2008, 06:33 PM
Hm... I know full well Porsche does their homework but is this really optimal? Lots of rear end down force but lots of front end lift? I can see how this would work well for low speed corners, but what about 100+ mph flat out corners??? How does a 996 GT2 compare in front lift and rear down force?
#34
07-11-2008, 08:14 PM
I'd also like to know the source of the data supporting the statement about friend end lift. Porsche's published data states the 996 GT3 RS has no net lift.
http://www.porscheengineering.com/fi...letype=default
http://www.porscheengineering.com/fi...letype=default
Hm... I know full well Porsche does their homework but is this really optimal? Lots of rear end down force but lots of front end lift? I can see how this would work well for low speed corners, but what about 100+ mph flat out corners??? How does a 996 GT2 compare in front lift and rear down force?
#35
07-12-2008, 10:29 PM
I'd also like to know the source of the data supporting the statement about friend end lift. Porsche's published data states the 996 GT3 RS has no net lift.
http://www.porscheengineering.com/fi...letype=default
http://www.porscheengineering.com/fi...letype=default
Your statement is right, net lift is close to zero for the GT3RS (and for the TT):
Front: - 19kgs
Rear: 25kgs
Net: 6kgs of downforce
996TT:
Front: - 7Kgs
Rear: 6kgs
Net: -1 KG of lift.
Carnerd, those front lift numbers are very small, those aerodynamic figures are among the best in the world. The higher rear downforce gives you faster acceleration out of a corner at speed and limits nosediving on braking, which reduces mass transfer to the front tires, and improves braking distance.
Consider this, at 125mph, the Corvette C6 has a net -82 kgs of lift, whereas the CGT has 89KGS of downforce. At top speed those downforce numbers get close to 400kgs (800lbs+). Now we know why the CGT is a track monster and a slow 0-300kph performer.
#37
07-13-2008, 02:02 PM
Join Date: Apr 2008
Location: Huntington NY & boca raton florida
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NO... I think my new tires just need to break in some more.. only have about 300 miles on them... BUT I am looking into coilover suspension for the near future.. I want something that is not too hard... because I only drive on street.. no track.. main thing is high speed feel control.. and less lean, I want it to feel more like my Lambo did if thats possible.. I dont know..
#38
07-13-2008, 03:19 PM
New tires definately feel a bit vague untill all the mold release/oils are worked out. But, you could also easily lower front tire pressure to see how you like the feel. Of course, what's good for steering isn't necessarily good for tire longevity with highway driving.
#39
07-13-2008, 03:59 PM
Very much so. Thanks Jean! I wonder how much difference the RS CF wing blade makes in terms of rear end down force compared to the stock 3?
#40
07-13-2008, 08:45 PM
Jean,
There is knock-off, supposedly of a Ruf chin spoiler, and it has small winglets at either side. The total width of the piece is 69" so the winglets can only be about about 1 1/2 inches per side. The pics are not clear but it appears there is a small air sluiceway between the winglet and the fender. In theory this should add downforce to an area that has lift in stock trim.
If it is a copy of a Ruf piece (which I can't find in their catalog) then there is a possibility of associated wind tunnel testing. Are you aware of the knock-off I'm talking about and are you aware of any downforce data?
Tnx,
Al
There is knock-off, supposedly of a Ruf chin spoiler, and it has small winglets at either side. The total width of the piece is 69" so the winglets can only be about about 1 1/2 inches per side. The pics are not clear but it appears there is a small air sluiceway between the winglet and the fender. In theory this should add downforce to an area that has lift in stock trim.
If it is a copy of a Ruf piece (which I can't find in their catalog) then there is a possibility of associated wind tunnel testing. Are you aware of the knock-off I'm talking about and are you aware of any downforce data?
Tnx,
Al
#41
07-13-2008, 10:34 PM
Al, sorry I don't know which wing you are talking about, the RT12 has 11kgs of lift in the front and 34 kgs of downforce in the rear. I am not sure if their supplier uses some sort of wind tunnel for their testing but I can find out. I know the front CTR2 bumper created lift for instance.
Never expect a Porsche aftermarket wing (regardless who builds it, no one has access to state of the art wind tunnel facilities) to give you results as good as Porsche's own, they will have either imbalanced lift fr/rr or disproportionate increased drag. The key is in getting drag and lift balanced, and that's why Porsche spends so much in wind tunnel testing. In a test conducted between 5 997TT modified tuner cars 9FF, Gemballa, Speedart, Techart, Wendland, and a stock 997TT, the stock 997TT achieved the fastest slalom speeds amongst all, certainly not related to aero alone, but it is an interesting comparison.
The 997GT2 has better aero data than the RT12 and was faster in almost every turn at the Nurburgring in its stock form, aero is fundamental to high speed handling, braking and top speed.
Last edited by Jean; 07-13-2008 at 10:49 PM.
#42
07-14-2008, 12:17 AM
It added 25 kgs (50+lbs) of downforce and increased front lift a bit (less than 15lbs) as a result at 125mph. I don't know what wing setting was used.
Al, sorry I don't know which wing you are talking about, the RT12 has 11kgs of lift in the front and 34 kgs of downforce in the rear. I am not sure if their supplier uses some sort of wind tunnel for their testing but I can find out. I know the front CTR2 bumper created lift for instance.
Never expect a Porsche aftermarket wing (regardless who builds it, no one has access to state of the art wind tunnel facilities) to give you results as good as Porsche's own, they will have either imbalanced lift fr/rr or disproportionate increased drag. The key is in getting drag and lift balanced, and that's why Porsche spends so much in wind tunnel testing. In a test conducted between 5 997TT modified tuner cars 9FF, Gemballa, Speedart, Techart, Wendland, and a stock 997TT, the stock 997TT achieved the fastest slalom speeds amongst all, certainly not related to aero alone, but it is an interesting comparison.
The 997GT2 has better aero data than the RT12 and was faster in almost every turn at the Nurburgring in its stock form, aero is fundamental to high speed handling, braking and top speed.
Al, sorry I don't know which wing you are talking about, the RT12 has 11kgs of lift in the front and 34 kgs of downforce in the rear. I am not sure if their supplier uses some sort of wind tunnel for their testing but I can find out. I know the front CTR2 bumper created lift for instance.
Never expect a Porsche aftermarket wing (regardless who builds it, no one has access to state of the art wind tunnel facilities) to give you results as good as Porsche's own, they will have either imbalanced lift fr/rr or disproportionate increased drag. The key is in getting drag and lift balanced, and that's why Porsche spends so much in wind tunnel testing. In a test conducted between 5 997TT modified tuner cars 9FF, Gemballa, Speedart, Techart, Wendland, and a stock 997TT, the stock 997TT achieved the fastest slalom speeds amongst all, certainly not related to aero alone, but it is an interesting comparison.
The 997GT2 has better aero data than the RT12 and was faster in almost every turn at the Nurburgring in its stock form, aero is fundamental to high speed handling, braking and top speed.
Thanks for all the info Jean!
#43
07-14-2008, 06:37 AM
Jean,
Here is a link to the spoiler I'm interested in.
http://cgi.ebay.com/ebaymotors/Porsc...3911.m14.l1318
Here is a link to the spoiler I'm interested in.
http://cgi.ebay.com/ebaymotors/Porsc...3911.m14.l1318
Last edited by Al Norton; 07-14-2008 at 05:03 PM.
#44
07-14-2008, 09:19 AM
Jean- this was one of the more interesting threads I've read in a long time. thanks.
A
A
#45
07-15-2008, 10:03 PM
Ard, this is a very complex field, whatever we know is a fraction of what is out there to know, but you are welcome and thank you. 
AL, now I know which one you are talking about. This is the same as the 993GT2 street front spoiler. The winglets are supposed to provide stability at highish speeds. I cannot tell you whether they will help or not, I know the factory 993 GT2 ones were functional and worked. The trick is that the slightest change in shape of the front lip might change all the dynamics of the air passing through the winglets and make it worse, but very difficult to tell except if put through a wind tunnel.
If you like the looks, go for it, I would not count on funcitonality of this modification much though, especially in the US where most of the driving is not very hgh speed.
Cheers
AL, now I know which one you are talking about. This is the same as the 993GT2 street front spoiler. The winglets are supposed to provide stability at highish speeds. I cannot tell you whether they will help or not, I know the factory 993 GT2 ones were functional and worked. The trick is that the slightest change in shape of the front lip might change all the dynamics of the air passing through the winglets and make it worse, but very difficult to tell except if put through a wind tunnel.
If you like the looks, go for it, I would not count on funcitonality of this modification much though, especially in the US where most of the driving is not very hgh speed.
Cheers