991s first track event
05-22-2013, 09:54 AM
#16
Nordschleife Master
05-22-2013, 10:39 PM
#18
Nordschleife Master
Jenk12m, your avatar is turn two at the Glen? I got my solo sign off Tuesday, and my first session I was first on the track. So my first track solo was with a totally open Watkins Glen track at my disposal! First lap was one of my top ten life moments!
05-23-2013, 12:25 AM
#20
Rennlist Member
Have fun, I'm a member there and actually got to drive another members 991s with aerokit. I'm a big fan of a manual and this was my 1st time driving the new pdk. I have to admit I was really impressed and I was only 1.5 second off my fastest lap in my RS. My buddies car was stock everything and I only did 3 laps
05-23-2013, 01:31 AM
#21
Tim K, lol, yes, talking about the spoiler only! Not sure how I missed that.
As was stated the down force doubles relative to the increase in speed, so lets say its good for 80 pounds at 80mph. If I am going into a corner at 80mph, decelerate to 70 and the wing goes down I now have zero down force instead of about 60 pounds at a time when I likely want whatever I can get.
Now are there a lot of corners exactly like this, and is the difference between no down force and 60 pounds (assuming that is even close to what it generates) going to make a big difference in how much speed I can carry right there? Probably not. However, by leaving the wing up, I have whatever down force is available and there is no sudden, artificial decrease due to the spoiler retracting when I might want whatever help it could provide.
As was stated the down force doubles relative to the increase in speed, so lets say its good for 80 pounds at 80mph. If I am going into a corner at 80mph, decelerate to 70 and the wing goes down I now have zero down force instead of about 60 pounds at a time when I likely want whatever I can get.
Now are there a lot of corners exactly like this, and is the difference between no down force and 60 pounds (assuming that is even close to what it generates) going to make a big difference in how much speed I can carry right there? Probably not. However, by leaving the wing up, I have whatever down force is available and there is no sudden, artificial decrease due to the spoiler retracting when I might want whatever help it could provide.
05-23-2013, 08:30 AM
#23
Race Car
Tim K, lol, yes, talking about the spoiler only! Not sure how I missed that.
As was stated the down force doubles relative to the increase in speed, so lets say its good for 80 pounds at 80mph. If I am going into a corner at 80mph, decelerate to 70 and the wing goes down I now have zero down force instead of about 60 pounds at a time when I likely want whatever I can get.
Now are there a lot of corners exactly like this, and is the difference between no down force and 60 pounds (assuming that is even close to what it generates) going to make a big difference in how much speed I can carry right there? Probably not. However, by leaving the wing up, I have whatever down force is available and there is no sudden, artificial decrease due to the spoiler retracting when I might want whatever help it could provide.
As was stated the down force doubles relative to the increase in speed, so lets say its good for 80 pounds at 80mph. If I am going into a corner at 80mph, decelerate to 70 and the wing goes down I now have zero down force instead of about 60 pounds at a time when I likely want whatever I can get.
Now are there a lot of corners exactly like this, and is the difference between no down force and 60 pounds (assuming that is even close to what it generates) going to make a big difference in how much speed I can carry right there? Probably not. However, by leaving the wing up, I have whatever down force is available and there is no sudden, artificial decrease due to the spoiler retracting when I might want whatever help it could provide.
05-23-2013, 08:32 AM
#24
Race Car
Tim K, lol, yes, talking about the spoiler only! Not sure how I missed that.
As was stated the down force doubles relative to the increase in speed, so lets say its good for 80 pounds at 80mph. If I am going into a corner at 80mph, decelerate to 70 and the wing goes down I now have zero down force instead of about 60 pounds at a time when I likely want whatever I can get.
Now are there a lot of corners exactly like this, and is the difference between no down force and 60 pounds (assuming that is even close to what it generates) going to make a big difference in how much speed I can carry right there? Probably not. However, by leaving the wing up, I have whatever down force is available and there is no sudden, artificial decrease due to the spoiler retracting when I might want whatever help it could provide.
As was stated the down force doubles relative to the increase in speed, so lets say its good for 80 pounds at 80mph. If I am going into a corner at 80mph, decelerate to 70 and the wing goes down I now have zero down force instead of about 60 pounds at a time when I likely want whatever I can get.
Now are there a lot of corners exactly like this, and is the difference between no down force and 60 pounds (assuming that is even close to what it generates) going to make a big difference in how much speed I can carry right there? Probably not. However, by leaving the wing up, I have whatever down force is available and there is no sudden, artificial decrease due to the spoiler retracting when I might want whatever help it could provide.
05-23-2013, 08:06 PM
#25
Rennlist Member
I always thought it was primarily for cooling, not downforce. Not sure about the 991s but certainly on the 981s I can't imagine the spoiler support linkage being able to transmit much force.
05-23-2013, 08:48 PM
#26
Race Car
The spoilers purpose is to, get ready, spoil. It moves the flow of air up and off of the rear of car, reducing lift and drag. Wings (inverted) generate downforce.
05-23-2013, 09:39 PM
#27
Chuckbdc, maybe I should just get a ball peen hammer and dimple it like a golf ball! ;-)
But I am now curious how much downforce is actually generated. Not even sure how to find out. Can't imagine the local dealer would have any idea. At least not mine...
But I am now curious how much downforce is actually generated. Not even sure how to find out. Can't imagine the local dealer would have any idea. At least not mine...
05-23-2013, 10:30 PM
#28
Race Car
Better, take a look at:
http://www.yourepeat.com/watch/?v=z_wgbrTc8tU
I could not find it, but somewhere on the web or at Porsche.com there is information about the amount of lift reduction with the standard front spoiler/rear spoiler and downforce with the Sport PASM front spoiler/rear extended spoiler settings.
05-23-2013, 10:44 PM
#29
Race Car
chuckj posted the following on 6speedonline on 4/40/12:
"I found some interesting technical data in the Porsche Service Information Technical Manual that I thought some might be interested in:
1. The 991C2S has ¼ sq. feet less drag than the 997C2S at ~6.25’.
2. The 991C2S has the same drag as the 997 C2 (~6.5’). Smaller wheels perhaps?
3. The PASM Sports chassis (-20mm) for the first time has zero total lift on the car and perhaps more importantly slight lift on the front (.02*) and rear (-.02*). The 997C2S has .05 and .02 respectively with a total lift of .07. Hopefully the track guys will confirm that this helps them in high speed corners.
ChuckJ
* Assume this is in KG as it was not marked"
"I found some interesting technical data in the Porsche Service Information Technical Manual that I thought some might be interested in:
1. The 991C2S has ¼ sq. feet less drag than the 997C2S at ~6.25’.
2. The 991C2S has the same drag as the 997 C2 (~6.5’). Smaller wheels perhaps?
3. The PASM Sports chassis (-20mm) for the first time has zero total lift on the car and perhaps more importantly slight lift on the front (.02*) and rear (-.02*). The 997C2S has .05 and .02 respectively with a total lift of .07. Hopefully the track guys will confirm that this helps them in high speed corners.
ChuckJ
* Assume this is in KG as it was not marked"
05-23-2013, 10:51 PM
#30
Race Car
Found it:
http://press.porsche.com/vehicles/12...oduct_Info.pdf
see:
"The rear spoiler extends to different heights and at different angles depending upon vehicle speed. It also features a flow element on its leading edge. The element is controlled by a special pivoting kinetic mechanism to assure optimal airflow over the spoiler blade. As a result, downforce approaching 200 pounds can be applied to the rear of the vehicle at maximum speed when equipped with the optional 20 mm lower Sports Suspension."
(note to parkerfe: you ain't gonna get anywhere near maximum speed at the Glen, just faster than you think you should be going just before right handers after the pit straight and a couple other places)
http://press.porsche.com/vehicles/12...oduct_Info.pdf
see:
"The rear spoiler extends to different heights and at different angles depending upon vehicle speed. It also features a flow element on its leading edge. The element is controlled by a special pivoting kinetic mechanism to assure optimal airflow over the spoiler blade. As a result, downforce approaching 200 pounds can be applied to the rear of the vehicle at maximum speed when equipped with the optional 20 mm lower Sports Suspension."
(note to parkerfe: you ain't gonna get anywhere near maximum speed at the Glen, just faster than you think you should be going just before right handers after the pit straight and a couple other places)