Why its ok to track a CGT but not other cabrios/roadsters
Discussion
"Porsche’s motor racing division designed and developed the Carrera GT’s body structure. The monocoque combines all structural functions. Unlike a conventional body shell made from numerous separate components, the monocoque is made from only a few elements that are bonded together in a high-pressure furnace to form a single or mono-structure that is exceptionally rigid and strong. Carbon fiber reinforced plastic (CFP) is the generic term for composite fiber materials that were developed primarily for aerospace applications but have been widely applied to motorsports vehicle construction. These materials provide supreme performance through their combination of minimum weight and maximum strength and stiffness. On the Carrera GT, CFP is used for the chassis, which includes the windshield frame (which is reinforced by a steel core) and supplemental safety bar system, engine/transmission support frame, doors, hoods, fenders, underfloor tray and even in many interior components.
The Carrera GT is the first road car built around such a chassis and also the first with an engine and transmission support made entirely of CFP, a concept developed by Porsche’s motorsports department and registered for patent. The system was devised because of carbon-reinforced plastic’s structural strength and thermal resistance. CFP is also used in the Carrera GT’s removable roof, which consists of two lightweight panels. It is held in place by rapid-action catches and can be stored in the car’s front luggage compartment.
The Carrera GT has steel reinforcement in its windshield structure and the longitudinal arms commonly referred to as chassis legs are made from high-strength stainless steel and help create a crash structure at the front and rear of the vehicle. Aluminum inserts connect the longitudinal arms to the chassis at the front and to the engine/transmission support frame at the rear. The bumper system is made of a strong aluminum crossbar and impact tubes."
Source: [url]www.seriouswheels.com/cars/top-2004-Porsche-Carrera-GT.htm[/url]
Other supercars like the Pagani Zonda, the Veyron and the Enzo, are not convertible. Is the CFP-made chassis the reason why the CGT can be tracked even if its a roadster?
Anyone out here is tracking a cabrio/roadster Porsche of some sort? What happens exactly?
Kay
PS: The Ferrari F50 was a roadster/cabrio, but had it's rear drivetrain attached to the engine, and the engine bolted to the front part of the car as well as some specific material used for the chassis, like the CGT.
The Carrera GT is the first road car built around such a chassis and also the first with an engine and transmission support made entirely of CFP, a concept developed by Porsche’s motorsports department and registered for patent. The system was devised because of carbon-reinforced plastic’s structural strength and thermal resistance. CFP is also used in the Carrera GT’s removable roof, which consists of two lightweight panels. It is held in place by rapid-action catches and can be stored in the car’s front luggage compartment.
The Carrera GT has steel reinforcement in its windshield structure and the longitudinal arms commonly referred to as chassis legs are made from high-strength stainless steel and help create a crash structure at the front and rear of the vehicle. Aluminum inserts connect the longitudinal arms to the chassis at the front and to the engine/transmission support frame at the rear. The bumper system is made of a strong aluminum crossbar and impact tubes."
Source: [url]www.seriouswheels.com/cars/top-2004-Porsche-Carrera-GT.htm[/url]
Other supercars like the Pagani Zonda, the Veyron and the Enzo, are not convertible. Is the CFP-made chassis the reason why the CGT can be tracked even if its a roadster?
Anyone out here is tracking a cabrio/roadster Porsche of some sort? What happens exactly?
Kay
PS: The Ferrari F50 was a roadster/cabrio, but had it's rear drivetrain attached to the engine, and the engine bolted to the front part of the car as well as some specific material used for the chassis, like the CGT.
barchetta_boy said:
Is it accepted wisdom that a cabrio / raodster cannot be tracked?
Joel
Joel
Interesting question that I ask as well. however, regarding the 50's, car hadnling was in another league. The thin tyres were far from producing the strain that we see today, thus making it a non-issue. I've read reports where fitting thick slicks on 70's cars (not super cars, normal cars) for severe tracking could end up cracking the windscreen!
magic torch said:
Suppose it comes down to what the car was originally designed to be. I'm guessing the 911 was designed to have a roof.
But that's the problem, I constantly read that Porsche engineers design the 911 as a cabrio first, therefore, making the cabrio variant much more rigid than other cabrios out there. So what is the trauma behind cabrios that trackers have?
Kay
There are no rules against tracking convertibles per se - although they are always (other things being equal) going to be less rigid than their fully closed monococque brothers - if they exist, so don't expect to see the Porsche Supercup running cabrios anytime soon.
I would bet you that a fully closed monococque CGT would also be stiffer than the actual car, but for what I assume were 'marketing reasons', they chose to build it as an open car in the knowledge that they knew they could achieve 'more than adequate' stiffness from the chosen design at 'an acceptable weight'.
I have been out on track in a friends track prepared 3.2 carrera cabrio and I was blown away by the experience. This car feels so planted and scary-fast (from the passnger seat) and almost up there with the 993 RS that I also rode in that day. I was really surprised by this as I had assumed that 'an old 911 cab' would have been 'nothing special' on the track. Big mistake!
This guy has an FIA approved triangulated half cage in the back which presumably gives a little extra stiffness and a reasonable amount of rollver protection and he's won his class in the series that he runs it in (in France) so it must be competitive....
Also, this 996 Cab. has just done 380,5kmph at Nardo...
I would bet you that a fully closed monococque CGT would also be stiffer than the actual car, but for what I assume were 'marketing reasons', they chose to build it as an open car in the knowledge that they knew they could achieve 'more than adequate' stiffness from the chosen design at 'an acceptable weight'.
I have been out on track in a friends track prepared 3.2 carrera cabrio and I was blown away by the experience. This car feels so planted and scary-fast (from the passnger seat) and almost up there with the 993 RS that I also rode in that day. I was really surprised by this as I had assumed that 'an old 911 cab' would have been 'nothing special' on the track. Big mistake!
This guy has an FIA approved triangulated half cage in the back which presumably gives a little extra stiffness and a reasonable amount of rollver protection and he's won his class in the series that he runs it in (in France) so it must be competitive....
Also, this 996 Cab. has just done 380,5kmph at Nardo...
Mogulboy said:
This guy has an FIA approved triangulated half cage in the back which presumably gives a little extra stiffness and a reasonable amount of rollver protection
As far as I know, a roll cage, or half a roll cage gives back some if not all of the stiffness that is lost from being roof less.
Roll bars that cross over the head of the driver from one side to the other, like the Carrera GT, and many other cars (Z4, in two roll hoops in one piece I think eventhough not sure), also gives some of it back, but not all.
Kay
Mogulboy said:
I have been out on track in a friends track prepared 3.2 carrera cabrio and I was blown away by the experience. This car feels so planted and scary-fast (from the passnger seat) and almost up there with the 993 RS that I also rode in that day. I was really surprised by this as I had assumed that 'an old 911 cab' would have been 'nothing special' on the track. Big mistake!
This guy has an FIA approved triangulated half cage in the back which presumably gives a little extra stiffness and a reasonable amount of rollver protection and he's won his class in the series that he runs it in (in France) so it must be competitive....
This guy has an FIA approved triangulated half cage in the back which presumably gives a little extra stiffness and a reasonable amount of rollver protection and he's won his class in the series that he runs it in (in France) so it must be competitive....
That'll be Nick's car then. He lives in Switzerland but they have no tracks there. I've driven that car round Paul Ricard (I was faster than him
) and there is very little body roll. Went round Magny Cours a few weeks ago with him driving (brakes gave up before I got a go 
), where there was a joint race/tack day weekend. The car feels very stable, but the lack of door bars worries me a bit. I like having a full cage round me when I race.
Yes, he's a good friend of mine. He didn't have the cage fitted though. He was at the garage having work done on his 964 C4 a few years ago and saw the cab there. It belonged to the garage owner's friend and he had looked after it (i.e. properly) for years. Nick bought it and a year or two later sold the 964 cos it then seemed too dull. The garage may have had the cage fitted in the past - they are RS Tuning of Geneva.
The 3.2 does go well, it had an engine rebuild this year and gearbox rebuild with different ratios and has 964 (big red?) brakes and pagid yellows, which stop it superbly on the Toyo 888s.
The 3.2 does go well, it had an engine rebuild this year and gearbox rebuild with different ratios and has 964 (big red?) brakes and pagid yellows, which stop it superbly on the Toyo 888s.
wildoliver said:
I do like that cage, it obviously doesnt hamper the roof either!
I also need to make a set of those light protectors, I have just broken my 3rd lens in as many months!
I also need to make a set of those light protectors, I have just broken my 3rd lens in as many months!
The roof works fine. I don't think you'll have been able to tell but the cage is even upholstered! Not sure how you're meant to check it's thickness though (for competition spec there are small holes so the tube wall thickness can be seen and determined to be adequate to meet regs).
I think the light protectors are easily available. I've seen them on a few race cars and keep thinking I should get some. I've not gone through many lenses but currently have LHD ones which were lying around his workshop so the mechanic 'donated' to this season's budget. Every little helps...........
Thats my car, I was suprised to see it on the piston heads web site!
The roll cage was fitted at the factory, I have been thinking about changing it for a stronger one with door bars. The roof will still fit if I change it but I only raced it this year for fun so will probably leave the car in its original form.
The light covers are common over here, I can find out where they come from if you would like.
The roll cage was fitted at the factory, I have been thinking about changing it for a stronger one with door bars. The roof will still fit if I change it but I only raced it this year for fun so will probably leave the car in its original form.
The light covers are common over here, I can find out where they come from if you would like.
Baby Blonde said:
The roll cage was fitted at the factory, I have been thinking about changing it for a stronger one with door bars. The roof will still fit if I change it but I only raced it this year for fun so will probably leave the car in its original form.
Baby Blonde, if the car didn't have a roll cage, would there be anything that you would have to do different, like use softer suspension, etc, and would the car drive differently without a roll cage?
I don't mean accident protection, I just mean chassis rigidity for tracking.
Kay
The car would twist a bit more if the cage was not there, the suspension bars on the car are standard, all I have changed is the front dampers to the Bilstien yellow. The car has always driven very well on track days but now I have been racing it this year I have found out that the brakes are still failing due to cracked disks and damaged pads. I am now using Pagid blacks and hope they cope better with the heat over a two hour race.
Edited by Baby Blonde on Thursday 7th December 07:29
Baby Blonde said:
The car would twist a bit more if the cage was not there, the suspension bars on the car are standard, all I have changed is the front dampers to the Bilstien yellow. The car has always driven very well on track days but now I have been racing it this year I have found out that the brakes are still failing due to cracked disks and damaged pads. I am now using Pagid blacks and hope they cope better with the heat over a two hour race.
Edited by Baby Blonde on Thursday 7th December 07:29
You have answered my curiosity. So there is an easily detectable difference between the chassis twist of a convertible car and one that isn't.
How does the "twist" manifest itself? Does the car simply slide more because the chassis can't keep the wheels to the ground rigidly? Or do you feel/hear anything? I'm very interested to know.
Kay
Gassing Station | Porsche General | Top of Page | What's New | My Stuff