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Spook's GT3 arrives!
- Thread starter pwebb
- Start date
http://www.hamiltongrays.com/2013-63-porsche-991-gt3-pdk-163129950_c6239.aspx £129,950 with Clubsport Package, Bi Xenon Headlights with PDLS, Telephone, Top Tinted Screen, Porsche VTS Tracker, 20 Inch Carrera GT3 Alloy Wheels
http://www.romansinternational.com/car/900/porsche-911-991-gt3 SOLD Leather & Alcantara Seats, Lifting System for Front Axle, 20" GT3 Alloys, Floor Mats, Sports Seats Plus, Guard Red Seat Belts, Sound Package Plus, Mobile Phone Preparation, Chrono Package Plus, PCM including Universal Audio Interface, Porsche Vehicle Tracking System
http://www.pistonheads.com/classifieds/used-cars/porsche/911-carrera-991/porsche-991-gt3/1980414 TBA WHITE 2014 991 GT3 COMFORT LIFTING FRONT AXEL BI-XONON LIGHT IN BLACK PRIVACY GLASS HEATED FRONT SEATS CRUISE CONTROL SOUND PACKAGE PLUS MOBILE PHONE PREPARATION CHRONO PACKAGE PLUS PCM WINDSCREEN TOP TINT VTS SUPAGARD (sic)
http://www.pistonheads.com/classifieds/used-cars/porsche/911-gt3-997/porsche-911-gt3-pdk/1992263?isexperiment=true £118,580 Carrera White with black Leather/Alcantara. Sound Package Plus, Grey Top Tinted Windscreen, Mobile Phone Preparation, Floor Mats, Bi Xenon Headlights in Black, Clear Glass Tail Lights, Lifting System Front Axle, Porsche Communication Management System, Sports Chrono Package Plus, 3rd Year Warranty, 3rd Year Porsche Assistance Cover, Porsche VTS Tracker
http://www.pistonheads.com/classifieds/used-cars/porsche/911-gt3-991/porsche-911-991-gt3-pdk-----------------2013/1970663?isexperiment=true £124,950 Metallic Basalt Black,Club sport package, Sports carbon back bucket seats, PCM, Bluetooth, Digital radio and sound package plus,Sport chrono package plus, Automatically dimming interior pack, Carbon centre console trim, Carbon interior package, Privacy glass, VTS, 3rd year extended warranty and 12-months road tax
Gotta go and do some work and stop spending the pension fund....
ORIGINAL: Motorhead
Clive,
Isn't the fact that, as you say, ceramics offer better initial bite a crucial point here? Under very hard brake application, will they not reach the ABS limit faster than their steel equivalent?
Jeff
I think if ABS is coming into play, you're misjudging speed for the prevailing conditions. The trick is to brake just short of lost tyre adhesion. With PCCB's you are able to brake later, which considerably aids your forward progress! [
Regards,
Clive.
Maybe we should be taking this topic to a new thread cap'n but I'm not sure that the coefficient of friction is the same for both types of brake. Very different materials are involved which will affect the driver's subjective assessment of the braking - pedal feel, brake bite, etc. - up to the limit of tyre adhesion. Maybe the ceramic brake characteristic "feel" (COF - related?) gives the driver more confidence?
Unfortunately I've no experience with PCCB, so it's just an ousider's comment.
Jeff
I meant the coefficient of friction between the tyre and road.[ORIGINAL: Motorhead
Maybe we should be taking this topic to a new thread cap'n but I'm not sure that the coefficient of friction is the same for both types of brake. Very different materials are involved which will affect the driver's subjective assessment of the braking - pedal feel, brake bite, etc. - up to the limit of tyre adhesion. Maybe the ceramic brake characteristic "feel" (COF - related?) gives the driver more confidence?
Unfortunately I've no experience with PCCB, so it's just an ousider's comment.
Jeff
http://www.caranddriver.com/features/the-power-to-stop-performance-cars-page-4
http://media.caranddriver.com/files/the-power-to-stoptech-stuff-the-power-to-stop-brake-test.pdf
If the PCCB gives the driver more confidence then that is another matter altogether which I wouldn't dispute.[
In practice I am not a great one for using the brakes more than absolutely necessary so for my style of driving it makes little difference whether the car's rotors are steel or ceramic. Nevertheless for an analysis of some of the variables this paper is an interesting read.
Note I have carefully avoided being drawn into giving an opinion!
http://stoptech.com/docs/media-center-documents/the-physics-of-braking-systems
ORIGINAL: tscaptain
I thought we had stopped the thread hijack! However Clive you just raised the very point that I was trying to get to. Why is tyre adhesion affected by the type of brake? Isn't the coefficient of friction the same for both? As wonderful as PCCBs are I stil don't get how they improve the tyres. Excuse my ignorance!
Bigger swept volume = better stopping power.[8|] Were it otherwise, we would all be using 4" rotors, saving both weight and cash.[
You're not ignorant, dear boy, just stubborn.[
Regards,
Clive,
I've been to Zuffenhausen many times and the last time I went in September, there were turbo S's and GT3s on the line one after the other and Porsche could make as many as they wanted but choose instead to limit production so making way for, dare I say it, rather dreary lesser models. It is simply not the case that GT3 production is limited for technical/supply reasons. It's a purely business decision.
I've told my salesman that since he can't supply me with a GT3 (in spite of him pushing a turbo S for all it/he was worth, especially the two "frustrated" sale examples sitting in the showroom), I'm going to stay where I am. It's a lost sale, not that Porsche will care one iota about losing business from some oik like me.
His theory was that GT3 production is limited because they lose money on every sale and only want to make as many as are needed for racing homologation purposes. True or not, I do not know, but the demand for the car suggests the other incarnations are tilted too far in the direction of GT/Autobahn stormers.
His theory was that GT3 production is limited because they lose money on every sale and only want to make as many as are needed for racing homologation purposes. True or not, I do not know, but the demand for the car suggests the other incarnations are tilted too far in the direction of GT/Autobahn stormers.
utter nonsense as the 991 GT3 is not for homologation.
call other OPCs, you may get lucky with a cancellation. PHer got a slot this way.
ORIGINAL: blueSL
......His theory was that GT3 production is limited because they lose money on every sale and only want to make as many as are needed for racing homologation purposes. True or not, I do not know, but the demand for the car suggests the other incarnations are tilted too far in the direction of GT/Autobahn stormers.
There's lots of myths going around about the 991 GT3, but that one takes the biscuit.
In fairness it was the same with the 997 GT3 and 996 GT3 Mk1 and RS. The production nos will probably reflect the true underlying demand for the first series. If Turbo production was similarly limited then we would probably be seeing the same hype.
ORIGINAL: tscaptain
4" rotors wouldn't be able to lock up the brakes, I suppose, a bit like the cars we learned to drive on! Also the in the comparison I'm talking about the cars have the same size rotors. However, let's continue this discussion over a beer rather than take up Peter's thread anymore. [] Not setting a good example.....[&:]
"The cross-drilled PCCB ceramic brake discs offer formidable braking performance. The use of six-piston aluminium monobloc fixed brake calipers on the front axle and four-piston units at the rear "" all finished in yellow "" ensures extremely high brake forces which, crucially, are exceptionally consistent.
PCCB enables shorter braking distances even in the toughest road and race conditions. Excellent fade resistance ensures greater balance when slowing from racetrack speeds.
Another key advantage of PCCB is the extremely low weight of the ceramic brake discs, which are approximately 50% lighter than standard discs of a similar design and size. As well as enhancing performance and fuel economy, this represents a major reduction in unsprung and rotating masses. The consequence of this is better road holding and increased comfort, particularly on uneven roads, as well as greater agility and improved handling."
Source Porsche Cars
Just came across this, didn't go looking for it - honest! [8|] Better make that 2 beers then! [
Regards,
Clive,
But in response to Clive, I would observe that Porsche Cars publications often have a whiff of the lawyer about them.
From Clive's quote:
"....shorter braking distances..." ...."greater balance when slowing from racetrack speeds......"
Than what?
And while it ought to be true that lower weight (as between ceramic and steel brake discs) should "enhance performance and fuel economy", I doubt if the benefit is quantifiable in the normal course of motoring.
By way of example another quote from a Porsche Cars source:
".....better "˜bite' characteristics under heavy braking and a further reduction in unsprung weight. The brakes are quick to apply and release, whilst the pedal travel is short and the bite point precise and consistent"
Actually the above quote was referring to brakes with red-painted calipers ie steel brakes. p66 of the 997 turbo brochure.
Note also that the only direct comparison in the original quote is to weight where Porsche are happy to state PCCB discs are approximately 50% lighter than standard discs of a similar design and size. Even that is a weasel worded and qualified statement. Why not give the actual figures?
My cynical view is that if Porsche could actually demonstrate a measureable advantage of PCCB over steel we would have heard about it; be it "˜Ring times or whatever. Meantime PCCB, and for that matter Centre Locks, are just a marketing gimmick and source of additional revenue.
As regards pure stopping distances it seems to me that the limiting factor is the coefficient of static friction between the tyre and the road. As long as the brake system is powerful enough to lock the rotor, which both steel and ceramic are able to do, the retardation is controlled by the road /tyre interface and the ABS.
Cheers
Nick
Meantime PCCB, and for that matter Centre Locks, are just a marketing gimmick and source of additional revenue.
Do Aston Martin, Bugatti, Ferrari, Lamborghini, Pagani,........owners know that? And they are paying a lot more for the benefits.
Surely pccbs are the optimum brakes on a road going performance Porsche. Not withstanding braking performance and stopping distances, there's:
- The unsprung weight saving (c.4kg per corner - factored up that's very significant)
- No fade
- No brake dust
- No corrosion
- Long life (100k mls +)
All of which are real benefits. And Supercup cars wouldn't be running them if it was a gimmick.
Those are indeed valid points, and some of my stuff needs to be taken with a pinch of salt but just by way of idle bar room chat my counterpoint comments are:
"¢ It would take someone more knowledgeable than me to set accurately the physical boundary between sprung and unsprung components but the rotors of course are just part of unsprung elements of the suspension system. Reducing their mass will help handling, and maybe to a lesser extent braking, but there is still plenty of other unsprung stuff such as hubs, tyres and a proportion of the driveshafts, suspension links etc all adding to the overall unsprung weight. Proportionately the rotors may add quite a small amount to the total. If you then look at the rotational effects of unsprung weight, then clearly a 1kg reduction in tyre weight would be more beneficial than an equivalent 1kg reduction in rotor weight. So quite how cost effective is the bang for buck of the unsprung weight reduction offered by ceramics I'm not sure.
"¢ Agree no fade. But then I never experienced brake fade with the steel rotors when on track in the 996 GT3. The tyres and driver went away well before the brakes. OK maybe I wasn't trying hard enough.
"¢ Less rather than no dust in my experience.
"¢ No corrosion is a definite plus
"¢ The life of ceramics seems a bit of a grey area. There is some anecdotal evidence of people wearing out ceramics with track use in much less than 100k miles, and then replacing with steel! However after 3 years the PCCB on the turbo were pretty much like new and I am sure they would have done 100k or more if I had kept the car.
Yes, point taken, gimmick not quite the right word for PCCB, I guess I had in mind the Centre Locks when I wrote that. However, a premium of £6,248 over standard steel rotors doesn't seem that good value for money and perhaps the cost penalty and fragility of ceramics makes them an unnecessary refinement for a road car.
Cheers
Nick
I guess apart from the theory and scripture, if someone and their driving style has experienced a noticeable difference between ceramic and steel then they can't be told they're wrong. Likewise someone who hasn't noticed a difference the way they drive. Not sure what would be the best way to quantify the performance difference. On a race car it would come down to lap times over a race distance, not a single lap. That could be a factor of brake fade over time etc over a race distance. A single braking distance test might not be a good way to measure it either.
The reduced unsprung mass would be hard to put a performance figure on, would depend on track layout, weather etc as to how effect it has. Don't know why Porsche says 'approx' 50% lighter. Might it be because the steel rotors on various 911 models are different sizes but if any model has PCCB's opted on then they get the same size PCCB, so the weight saving could be on average 50%. Don't know, haven't checked. Picked up a steel and PCCB rotor and the weight difference is significant in the hand. How much that helps the wheel travel up and down over bumps to keep road contact (vs a higher mass's higher inertia) I don't know, but on a very smooth surface that aspect will have little effect at all. How best to quantify it for a brochure I don't know.
So I guess the benefits are subtle and some will experience them whilst others won't. If I drove both and felt a benefit I'd buy and if I didn't I wouldn't. Ticking the PCCB option based on the brochure might be a waste of money for some.
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