CGT Prices - Page 166 - Rennlist - Porsche Discussion Forums

Notices
Porsche Supercars Carrera GT, 918,960

CGT Prices

Reply

Old 01-12-2018, 04:15 PM
  #2476
W8MM
Addict
Rennlist Member

 
W8MM's Avatar
 
Join Date: Nov 2002
Location: Cincinnati, USA
Posts: 1,050
Default

Originally Posted by E-Man View Post
but it can be destroyed by slipping while lots of throttle is applied

Mike, Isn't that exactly what Christijan is doing in the video?
I didn’t watch the video. Maybe he’s destroying the clutch? Ask David Donohue or Hurley Haywood if you don’t believe me.

As they say, “One can always go fastest in someone else’s car!”
W8MM is offline  
Reply With Quote
Old 01-12-2018, 05:34 PM
  #2477
E-Man
Addict
Rennlist Member
 
E-Man's Avatar
 
Join Date: Dec 2008
Posts: 419
Default

Mike,I think you misunderstood me, I believe you 100%. I am asking you if you watch the video, doesn't it appear that he's putting excessive wear on the clutch?
E-Man is offline  
Reply With Quote
Old 01-12-2018, 06:50 PM
  #2478
W8MM
Addict
Rennlist Member

 
W8MM's Avatar
 
Join Date: Nov 2002
Location: Cincinnati, USA
Posts: 1,050
Default

Originally Posted by E-Man View Post
Mike,I think you misunderstood me, I believe you 100%. I am asking you if you watch the video, doesn't it appear that he's putting excessive wear on the clutch?
OK, I watched the video.

The driver seems to be “hot *******” the throttle application quite a bit, but notice that he doesn’t keep the revs up as he engages the clutch to start moving. It’s mostly audio entertainment and not big time clutch abuse.

OTOH, I wouldn’t recommend copying his technique because there are a number of ways to get it wrong that would be detrimental to clutch life.
W8MM is offline  
Reply With Quote
Old 01-12-2018, 10:07 PM
  #2479
nuvolari612
Addict
Rennlist Member
 
nuvolari612's Avatar
 
Join Date: Sep 2010
Location: midwest
Posts: 1,683
Default

Pasted a link to the entire article - few items below that shed some light on the operations of the clutch / transmission.

https://www.stuttcars.com/porsche-models/carrera-gt/

Ceramic clutch


The Carrera GT is also the first car in the world equipped with a ceramic clutch. It is called PCCC or Porsche Ceramic Composite Clutch. The two-plate clutch diameter is only 169 mm / 6.65" and it allows a maximum torque of 1000 Nm. The clutch weighs just 3.5 kg / 7.7 lb which is 1/3 of the mass of the 996 Turbo clutch. And due to the low clutch diameter the mass moment of inertia accounts for only 1/10.Transmission

The extremely severe requirements with regard to the overall concept of the car excluded the installation of a standard transmission. In order to cope with the specific boundary conditions in terms of input torque, wheelbase, aerodynamics and center-of-gravity level, a completely new transmission was developed for the Carrera GT. It was decided to use a transverse transmission with integrated engine oil tank and cyclone separator for oil foam suppression. With this concept, the masses are concentrated at the center of gravity while providing space enough for the installation of a aerodynamic diffusor across the entire width of the car. Due to the need to use a clutch as compact as possible, the Carrera GT does not come with a two-mass flywheel – but the function of such a flywheel is provided nevertheless by the special design of the input shafts: the first main shaft is hollow, with a long and thin full shaft running inside as a spring rod. Together with the mass weight of the angle drive the two shafts acting as a torsion spring serve to absorb possible jolts coming from the engine, reducing transmission noise in the process.







nuvolari612 is offline  
Reply With Quote
Old 01-17-2018, 05:52 AM
  #2480
Better4Worse
User
 
Join Date: Aug 2015
Posts: 17
Default

Originally Posted by W8MM View Post
The Carrera GT clutch "problem" has nothing to do with the clutch. It has to do with the teeny-tiny flywheel inertia built into the engine. The low rotating mass allows the engine to rev like a motorcycle and supplies very little rotational energy to "dump" into a starting-from-rest event.

Plenty of drivers like to rev the engine a little (stores up some rotational energy) and then let out the clutch while the revs are still up. This driver-dependent technique usually can be gotten away with in cars with ordinary high-mass flywheels because the flywheel has enough stored energy to move the car from rest before it is all used up. Not so with the Carrera GT. If one used this technique with a CGT, one immediately stalled the car because all the flywheel energy was exhausted before the engine turned over a few revolutions.

Even Car and Driver summed up trying to get good 1/4-mile times or 0-60 times as "burn, buck, or stall". All from side-effects of that gorgeous, motorcycle-like, free-revving, low-mass flywheel.

The "idle-control" loop in the ECU was augmented to be able to keep the car running after clutch release with no throttle application as a driver workaround.
Originally Posted by W8MM View Post
"Manual blipping before it grabs" won't work because the blipping only lasts a fraction of a second. The blip dies before engagement and the car stalls. To make blipping-before-grab successful, a more conventional flywheel is required so that there is enough energy left to keep the engine running when the clutch finally grabs. Adding throttle at the exact same time it grabs (not before) is what is needed.

The ECU programming doesn't "blip" anything. It merely struggles to keep the engine at idle speed when releasing the clutch tries to slow down the engine as it grabs. The ECU programming is powerful enough to smoothly maintain idle during move-off. The engine by itself would never experience that sort of trouble trying to stay running. Idling at rest and then maintaining idle as one releases the clutch is not the usual task of the ECU, so it required inventive programming.

I found that keeping my foot off of the throttle was fabulous for maneuvering around the garage or parking lot. I didn't like it so much for regular traffic starts. Since I was already used to driving cars with racing engines that had very small flywheels, I was easily able to adjust to the CGT engine/clutch requirements after only a few traffic starts. If one is new to light flywheel cars, it can take longer to learn how to coordinate gas and clutch.

Some early owners refused to learn how to move off from rest in a coordinated way and fried the clutch by slipping the crap out of it on start up. The CGT clutch is plenty capable of the task at hand, but it can be destroyed by slipping while lots of throttle is applied.
Thank you for sharing the encyclopedic explanation.

Few people understand the GT's engineering meticulously , even fewer are able to articulate it so clearly !
Better4Worse is offline  
Reply With Quote
Old 01-18-2018, 01:17 AM
  #2481
Sterling Sackey
User
 
Join Date: May 2016
Posts: 38
Default

Originally Posted by Better4Worse View Post
Thank you for sharing the encyclopedic explanation.

Few people understand the GT's engineering meticulously , even fewer are able to articulate it so clearly !
Agreed, great explanation and description of the actual issue at hand.
Sterling Sackey is offline  
Reply With Quote
Old 01-19-2018, 11:32 AM
  #2482
nuvolari612
Addict
Rennlist Member
 
nuvolari612's Avatar
 
Join Date: Sep 2010
Location: midwest
Posts: 1,683
Default

No offense ... looking at an 04 meeting with a tech who has worked on CGT's for years trying to find out if somethings changed later on the CGT system. Originally this system per Porsche was supposed to last 100,000 miles. The throttle blips up to an additional 2 - 400 rpm's that's a blip IMO and others click the link. The prior owner of my CGT was a race car driver not to be named - the clutch after 5500 miles showed little use and he stated that he accelerated from a dead stop after that conversation the salesman and prior owner suggested not to touch the gas and let the system do it's job. Purchased a brand new clutch off the shelf to have a spare and learn about the clutch operating system. It's the biggest issue with the CGT I think it deserves clarity.

https://www.6speedonline.com/forums/...ays-cgt-2.html

Last edited by nuvolari612; 01-19-2018 at 11:52 AM.
nuvolari612 is offline  
Reply With Quote
Old 01-19-2018, 12:15 PM
  #2483
W8MM
Addict
Rennlist Member

 
W8MM's Avatar
 
Join Date: Nov 2002
Location: Cincinnati, USA
Posts: 1,050
Default

Originally Posted by nuvolari612 View Post
No offense ... looking at an 04 meeting with a tech who has worked on CGT's for years trying to find out if somethings changed later on the CGT system. Originally this system per Porsche was supposed to last 100,000 miles. The throttle blips up to an additional 2 - 400 rpm's that's a blip IMO and others click the link. The prior owner of my CGT was a race car driver not to be named - the clutch after 5500 miles showed little use and he stated that he accelerated from a dead stop after that conversation the salesman and prior owner suggested not to touch the gas and let the system do it's job. Purchase a brand new clutch off the shelf to have a spare and learn about the clutch operating system. It's the biggest issue with the CGT I think it deserves clarity.

https://www.6speedonline.com/forums/...ays-cgt-2.html
OK. I guess we're just talking semantics. You'll notice in that old 6speedonline post I used quotation marks around "blip". The small increase in RPM when the idle servo reacts to the clutch engagement is just mild overshoot of the feedback-control loop in the ECU/engine system. When most people speak of blipping the throttle they mean jabbing the pedal and getting 1,000 or more RPM rise out of the engine. The ECU doesn't "jab" the throttle, it tries to smoothly increase the engine's output to make up for the drag of the car moving off from rest. It's the nature of control loop design to trade a little overshoot of the intended target RPM so as to react quickly enough to the stimulus of the clutch drag. So, it overdoes the idle stability by a few hundred RPM is some situations.
W8MM is offline  
Reply With Quote
Old 01-19-2018, 04:45 PM
  #2484
Sterling Sackey
User
 
Join Date: May 2016
Posts: 38
Default

Sold for $715,000 at Gooding Scottsdale 2018 after buyer's premium:

https://www.goodingco.com/vehicle/20...-carrera-gt-3/
Sterling Sackey is offline  
Reply With Quote
Old 01-19-2018, 05:00 PM
  #2485
jvmax
Addict
Rennlist Member
 
jvmax's Avatar
 
Join Date: Apr 2007
Location: orlando, fl
Posts: 920
Default

Originally Posted by Sterling Sackey View Post
Sold for $715,000 at Gooding Scottsdale 2018 after buyer's premium:

https://www.goodingco.com/vehicle/20...-carrera-gt-3/
$650k was hammer price, 2800 mile silver/ascot brown
jvmax is offline  
Reply With Quote
Old 01-19-2018, 05:05 PM
  #2486
Sterling Sackey
User
 
Join Date: May 2016
Posts: 38
Default

Correct, originally delivered to Tim Allen. I would say that's a growth sale!
Sterling Sackey is offline  
Reply With Quote
Old 01-19-2018, 05:07 PM
  #2487
CGT000
User
 
CGT000's Avatar
 
Join Date: Dec 2013
Location: NYC
Posts: 664
Default

Originally Posted by Sterling Sackey View Post
Correct, originally delivered to Tim Allen. I would say that's a growth sale!
Learning new things every day. What is a "growth sale"?
CGT000 is offline  
Reply With Quote
Old 01-19-2018, 05:09 PM
  #2488
Sterling Sackey
User
 
Join Date: May 2016
Posts: 38
Default

Originally Posted by CGT000 View Post
Learning new things every day. What is a "growth sale"?
In other words, it indicates that the market is going back up for the CGT, at least based on other auction results and private sales I've seen over the past year.
Sterling Sackey is offline  
Reply With Quote
Old 01-19-2018, 05:13 PM
  #2489
CGT000
User
 
CGT000's Avatar
 
Join Date: Dec 2013
Location: NYC
Posts: 664
Default

Originally Posted by Sterling Sackey View Post
In other words, it indicates that the market is going back up for the CGT, at least based on other auction results and private sales I've seen over the past year.
Thank you for the explanation and that is good news!
CGT000 is offline  
Reply With Quote
Old 01-20-2018, 02:52 AM
  #2490
F40-r
User
 
Join Date: Jan 2016
Posts: 58
Default

As owners, we all want them to be worth $1 million already!

The CGT is still lagging behind a few other cars and the gap between the CGT and 918 is quite huge to say the least.

nonetheless, we’re off to a good start, let’s see where it takes us this year.
F40-r is offline  
Reply With Quote
 

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
964TURBOCHAS
911 Forum
34
12-09-2016 12:45 AM
Ronan
Rennlist Canada
19
09-30-2016 05:01 PM
Veloce Raptor
Racing & Drivers Education Forum
82
04-12-2016 11:42 AM
jrgordonsenior
Racing & Drivers Education Forum
20
01-28-2016 02:46 PM
Noahs944
924/931/944/951/968 Forum
2
01-14-2016 10:48 AM


Thread Tools
Search this Thread
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -3. The time now is 01:13 PM.


Copyright © 1998 - 2017 Rennlist.com We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: