Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > Porsche 911 Technical Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
wastintime's Avatar
 
Join Date: Nov 2001
Location: Bethesda, MD
Posts: 1,625
Send a message via AIM to wastintime
downforce of carrera vs. turbo spoilers

Hey everyone,
I have the stock spoiler that came on my RSA, which is the carrera tail. It had been suggested that a very easy way to add more downforce would be to swap out the carrera rubber for the rubber from an early (pre-964) turbo tail. Does anyone happen to know the actual difference in downforce?

Thanks,
Andrew
Old 06-22-2004, 08:42 AM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Aug 2002
Location: Orchard Park, NY
Posts: 10,521
Porsche published the differences and were once found in the Up-Fixin series published by PCA. Bill Verburg has the same graphs.

The Turbo style provides more downforce, but in either case the downforce generated is not enough to overcome the rear lift inherent in the car's body shape. There is still "net" lift. The difference is about 50 lbs of additonal downforce for the Turbo vs Carrera tail at 150 mph, or so....as I recall ( don't have those publications in front of me at the moment).

BTW....if you increase the downforce in the rear if you, how do you counter-balance the front? How do you intend to add more front downforce if you add a Turbo rear tail?

---Wil
__________________
Wil Ferch
85 Carrera ( gone, but not forgotten )
Old 06-22-2004, 09:02 AM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Registered User
 
Join Date: May 2004
Location: washington,DC
Posts: 1,087
RUF opted for the Carrera tail on the yellowbird,according to RUF it offered enough downforce with less drag then the turbo version.This was a car capable of over 200 mph,safely,from what the testers said it was pretty stable.RUF had an underbody spoiler also which was a rubber lip similar to the 914.
__________________
my life begins at 150MPH
Old 06-22-2004, 09:15 AM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Registered User
 
Hald's Avatar
 
Join Date: Sep 2002
Location: Pepperell, MA
Posts: 211
Let's see if this is legible when reduced from >500KB ...

__________________
Mark
'77 Carrera 3.0
http://members.rennlist.com/hald
Old 06-22-2004, 11:56 AM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Aug 2002
Location: Orchard Park, NY
Posts: 10,521
From Fig 2....if we assume "turbo" means early turbo that is much like the Carrera spoiler...and if we assume "3.3 Turbo" is the commonly-held view of the later high-sided turbo style....

...then the 50 lbs difference is about right at 150 mph, it seems...

---Wil
__________________
Wil Ferch
85 Carrera ( gone, but not forgotten )
Old 06-22-2004, 01:10 PM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
which ain't much, in my opinion.

plus the carrera and turbo 3.0 tails look better than the turbo 3.3 tail, if you have to have a tail (IMHO). I'm really surprised the ducktail is that close to the turbo 3.0. looks like 20-25 pounds perhaps. drag might be a different story...

Mark, were there drag numbers or graphs from that same source?

TIA
__________________
Andy
Old 06-22-2004, 01:39 PM
  Pelican Parts Technical Article Directory    Reply With Quote #6 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 21,822
Garage
Groan, , a search of 'downforce and drag' might be educational
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 06-22-2004, 01:52 PM
  Pelican Parts Technical Article Directory    Reply With Quote #7 (permalink)
Registered User
 
wastintime's Avatar
 
Join Date: Nov 2001
Location: Bethesda, MD
Posts: 1,625
Send a message via AIM to wastintime
I understand that it's going to make more drag, but I'm not really as concerned with drag as I am getting as much downforce in the rear as possible without changing tails. I'm going to switch to the turbo rubber, I was just curious how much more downforce it actually generated.

I already kinda felt like the front needs splitters with just the carrera tail, so i'm sure the splitters will do their job with the turbo element as well.
__________________
-Andy

'67 912, '92 C2, and '93 RSA - all gone
Old 06-22-2004, 02:25 PM
  Pelican Parts Technical Article Directory    Reply With Quote #8 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
Quote:
Originally posted by Bill Verburg
Groan, , a search of 'downforce and drag' might be educational
My apologies. I just asked about drag since we were already talking about lift. I did a search on your suggestion, lots of info. No need to rehash.
__________________
Andy
Old 06-22-2004, 02:44 PM
  Pelican Parts Technical Article Directory    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Dec 2001
Location: MA USA
Posts: 2,938
Nice groan Bill
__________________
Dean
911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno,
Old 06-22-2004, 02:46 PM
  Pelican Parts Technical Article Directory    Reply With Quote #10 (permalink)
Registered User
 
Hald's Avatar
 
Join Date: Sep 2002
Location: Pepperell, MA
Posts: 211
__________________
Mark
'77 Carrera 3.0
http://members.rennlist.com/hald
Old 06-22-2004, 03:29 PM
  Pelican Parts Technical Article Directory    Reply With Quote #11 (permalink)
Registered User
 
Join Date: Feb 2004
Location: Frankfurt/Germany
Posts: 33
Hi,

I was thinking about the turbo rubber on my Carrera spoiler, too, to get more downforce in the rear. I only wanted to change the rubber, not the body of the spoiler, but there are 2 things I do not know:

1. Does the turbo rubber fit with the same holes as the Carrera spoiler?

2. Is the higher downforce (50 lbs) of the turbo spoiler to much for the Carreras spoiler body (would the spoiler crack or would the engine lid get damaged?), because the backside of the turbo spoilerbody has an other shape?

But I dont see any problems with the balance, when the turbo spoiler is installed, because the factory sold the SCs with the turbo rear spoiler.

Thorsten
Old 06-22-2004, 03:48 PM
  Pelican Parts Technical Article Directory    Reply With Quote #12 (permalink)
Registered User
 
North Coast Cab's Avatar
 
Join Date: Sep 2002
Location: Cleveland
Posts: 4,408
Garage
Bruce Andersons book shows several 911's on the cover and many of them have the Carrera tail with an added plexiglass piece to extend them. I always wondered if anyone ran one of these and if so how they performed.

John
__________________
1985.5 944 GTS
Old 06-22-2004, 04:09 PM
  Pelican Parts Technical Article Directory    Reply With Quote #13 (permalink)
Registered User
 
Hald's Avatar
 
Join Date: Sep 2002
Location: Pepperell, MA
Posts: 211
this may be a technicality, but, as I understand it, the various 911 spoilers we're talking about do not create "downforce". They "spoil" lift. The distinction being, if all lift were able to be removed by a spoiler, then the car would be no lighter, or heavier, than its static weight. A wing that exerts downforce, however, results in the car in motion actually being pushed on its suspension more than the weight of the car, alone.
__________________
Mark
'77 Carrera 3.0
http://members.rennlist.com/hald
Old 06-22-2004, 04:23 PM
  Pelican Parts Technical Article Directory    Reply With Quote #14 (permalink)
Registered User
 
}{arlequin's Avatar
 
Join Date: Jun 2003
Location: DC/Boston
Posts: 5,496
Garage
Reading this made me laugh, mostly due to this classic: 911 rake front/rear
__________________
dave
1973,5: one two thweeee!
no.don't.stop.
Old 06-22-2004, 04:43 PM
  Pelican Parts Technical Article Directory    Reply With Quote #15 (permalink)
Registered User
 
wastintime's Avatar
 
Join Date: Nov 2001
Location: Bethesda, MD
Posts: 1,625
Send a message via AIM to wastintime
mark,
these really are more wings than spoilers, just look at a carrera tail from the side, you can't help but notice it looks exactly like an aircraft wing with its flaps extended, that's why they use the lip extensions in Bruce Anderson's book, more drag, but much more downforce. The fact that depending upon the tail it isn't enough to completely counteract the lift the car generates doesn't mean it's simply spoiling the air rather than creating downforce. If you look at the graph, the 3.3 turbo tail compared to a car with no spoilers does almost negate the lift at speed.
__________________
-Andy

'67 912, '92 C2, and '93 RSA - all gone
Old 06-23-2004, 02:06 AM
  Pelican Parts Technical Article Directory    Reply With Quote #16 (permalink)
Registered User
 
Hald's Avatar
 
Join Date: Sep 2002
Location: Pepperell, MA
Posts: 211
I should know better than to try to add to a conversation on a subject about which I know nothing...
__________________
Mark
'77 Carrera 3.0
http://members.rennlist.com/hald
Old 06-23-2004, 02:43 AM
  Pelican Parts Technical Article Directory    Reply With Quote #17 (permalink)
Registered User
 
david914's Avatar
 
Join Date: Jun 2002
Location: Richmond, VA
Posts: 1,416
OK, while we're on the subject, how does the front chin spoiler function? Does it create a vacuum under the car by directing air around the car rather than under it, or ???
__________________
David Dryden
'86 911 Coupe
'05 BMW X5 4.4i
Old 06-23-2004, 08:21 AM
  Pelican Parts Technical Article Directory    Reply With Quote #18 (permalink)
Registered User
 
}{arlequin's Avatar
 
Join Date: Jun 2003
Location: DC/Boston
Posts: 5,496
Garage
I think it just directs more air over the car than otherwise would be possible without it.
__________________
dave
1973,5: one two thweeee!
no.don't.stop.
Old 06-23-2004, 08:24 AM
  Pelican Parts Technical Article Directory    Reply With Quote #19 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
Quote:
Originally posted by david914
OK, while we're on the subject, how does the front chin spoiler function? Does it create a vacuum under the car by directing air around the car rather than under it, or ???
It reduces the amount of air getting stuffed under the car.
__________________
Andy
Old 06-23-2004, 08:50 AM
  Pelican Parts Technical Article Directory    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 09:03 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2016 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.