The great CGT acceleration lie ?
07-07-2007, 01:07 PM
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The great CGT acceleration lie ?
The Porsche handbook acceleration diagram shows a 0-300kph (186.3mph) in around 27s.
It states that this is for a car at DIN empty weight and with a 50% load without additional equipment which seems to be a car with no extras (ie a/c etc) at the 1380kg DIN weight + two people.
I have no idea if such a bare car exists but the majority of CGTs are like the one tested in Sport Auto magazine which did the 0-300kph sprint in 34s. with 100-300kph taking 30.2s.
I have just finished running at an airstrip and logged 7 runs (with 2 people on board and at least half a tank of fuel) The average 100-300kph was 29.52s or an equivalent 0-300kph in 33.3s with a best of 28.62s or 0-300kph in 32.42s.
I find it very hard to believe that there is a CGT out there which can lop 5+seconds off this time
BTW the CGT was sooooo stable at 195mph, virtually hands off and a spine tingling mix of sensations
Edit: Looking at the handbook acceleration diagram it seems that I am not hanging onto the gears quite as long as they do, but still not whole seconds worth of difference...
It states that this is for a car at DIN empty weight and with a 50% load without additional equipment which seems to be a car with no extras (ie a/c etc) at the 1380kg DIN weight + two people.
I have no idea if such a bare car exists but the majority of CGTs are like the one tested in Sport Auto magazine which did the 0-300kph sprint in 34s. with 100-300kph taking 30.2s.
I have just finished running at an airstrip and logged 7 runs (with 2 people on board and at least half a tank of fuel) The average 100-300kph was 29.52s or an equivalent 0-300kph in 33.3s with a best of 28.62s or 0-300kph in 32.42s.
I find it very hard to believe that there is a CGT out there which can lop 5+seconds off this time
BTW the CGT was sooooo stable at 195mph, virtually hands off and a spine tingling mix of sensations
Edit: Looking at the handbook acceleration diagram it seems that I am not hanging onto the gears quite as long as they do, but still not whole seconds worth of difference...
Last edited by TB993tt; 07-07-2007 at 02:37 PM.
07-07-2007, 01:43 PM
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Excellent information TB 
It is virtually impossible for any CGT to improve this time by 5 seconds, unless it has different specs. Since your car and any other tested independently is showing these times, I can see no other explanation other than Porsche "lied"? Pretty serious stuff.
It is virtually impossible for any CGT to improve this time by 5 seconds, unless it has different specs. Since your car and any other tested independently is showing these times, I can see no other explanation other than Porsche "lied"? Pretty serious stuff.
07-07-2007, 04:12 PM
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Hi to all, just joined Rennlist and this forum after a friend in Germany told me about it. Great for picking up a load of info and ideas.
TB993tt, read with interest the figures you got out of the car. I too have had some slower times than the advertised. I took it up with Porsche and their reponse seemed to make sense. As I remember it, some of it was as follows:
The options fitted to the cars adds not only weight but the a/c in particular consumes very valuable HP at the critical period needed, ie. at the top end when battling the forces, especially if the compressor is running. Not sure if yours was........
The weight calculated for 2 people is just 65Kg each! That's almost one of me!
Temp and humidity play an increasing effect the faster the speed, as does the fuel octane rating.
I have recently switched to using the new BP Ultimate 102. The effect on performance was simply amazing, especially in the mid range. It expensive at £2.50/l but worth it if you want to hit and sometimes beat the advertised specs........and you will, options or not!
TB993tt, read with interest the figures you got out of the car. I too have had some slower times than the advertised. I took it up with Porsche and their reponse seemed to make sense. As I remember it, some of it was as follows:
The options fitted to the cars adds not only weight but the a/c in particular consumes very valuable HP at the critical period needed, ie. at the top end when battling the forces, especially if the compressor is running. Not sure if yours was........
The weight calculated for 2 people is just 65Kg each! That's almost one of me!
Temp and humidity play an increasing effect the faster the speed, as does the fuel octane rating.
I have recently switched to using the new BP Ultimate 102. The effect on performance was simply amazing, especially in the mid range. It expensive at £2.50/l but worth it if you want to hit and sometimes beat the advertised specs........and you will, options or not!
07-07-2007, 07:21 PM
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Originally Posted by scaric
20C4S,
Yes its Polar Silver, one of two I am told.
Yes its Polar Silver, one of two I am told.
Nice color choice, enjoy it in good health and welcome in rennlist.
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07-07-2007, 07:41 PM
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Originally Posted by scaric
Hi to all, just joined Rennlist and this forum after a friend in Germany told me about it. Great for picking up a load of info and ideas.
TB993tt, read with interest the figures you got out of the car. I too have had some slower times than the advertised. I took it up with Porsche and their reponse seemed to make sense. As I remember it, some of it was as follows:
The options fitted to the cars adds not only weight but the a/c in particular consumes very valuable HP at the critical period needed, ie. at the top end when battling the forces, especially if the compressor is running. Not sure if yours was........
The weight calculated for 2 people is just 65Kg each! That's almost one of me!
Temp and humidity play an increasing effect the faster the speed, as does the fuel octane rating.
I have recently switched to using the new BP Ultimate 102. The effect on performance was simply amazing, especially in the mid range. It expensive at £2.50/l but worth it if you want to hit and sometimes beat the advertised specs........and you will, options or not!
TB993tt, read with interest the figures you got out of the car. I too have had some slower times than the advertised. I took it up with Porsche and their reponse seemed to make sense. As I remember it, some of it was as follows:
The options fitted to the cars adds not only weight but the a/c in particular consumes very valuable HP at the critical period needed, ie. at the top end when battling the forces, especially if the compressor is running. Not sure if yours was........
The weight calculated for 2 people is just 65Kg each! That's almost one of me!
Temp and humidity play an increasing effect the faster the speed, as does the fuel octane rating.
I have recently switched to using the new BP Ultimate 102. The effect on performance was simply amazing, especially in the mid range. It expensive at £2.50/l but worth it if you want to hit and sometimes beat the advertised specs........and you will, options or not!
You are quite correct about the weight, I worked out the 65kg per person based on the 1380kg and of course it seems a bit "lite"
so it seems that they ran a zero option car with one person (driver) on board to get the times ?I spoke to my man at RS Tuning (who have close contact with the race side of Porsche and are the only company (currently) to offer credible tuning packages for the CGT) to ask how to get the best times and moreover how can the factory quote ~27s when Sport Auto got ~34s !!!
He had no definitive reply (unusual for a German tuner
) but mused that the factory test drivers used a lighter weight car and published the best numbers they had ever seen during testing....It still seems wrong, even with 100kg off (passenger/a/c/etc) you are not going to find 5 seconds !! ?
I too have used that 102 stuff and it is proper fuel but for a naturally aspirated like the CGT I really can't see it making THAT much difference - the ambient temperature was a DIN 20DegC and the pressure was right around DIN...
BTW I switched the air con off at the start of every run.
Obviously the issue is academic, but things like this need a definative answer IMO and it would be great to know what it is....
Regardless of this the CGT is an intoxicating thing.......
07-07-2007, 08:52 PM
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TB, seems that you have all the bases are covered here. You are right, something is not quite right. I will be at the factory in a few days (car is there for the annual service/warranty work and having the stone guard applied) and I shall ask the question on the off chance they might commit! Even at 32.42s, I bet you had fun though! 
ICON, pics on there.
NETBURNER, you are welcome to add it to your list.
ICON, pics on there.
NETBURNER, you are welcome to add it to your list.
07-07-2007, 09:44 PM
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Originally Posted by netburner
If you would like to be added to my registry (www.CarreraGTRegistry.de.vu) please contact me. The other polar silver CGT is within that registry as well
Nice color choice, enjoy it in good health and welcome in rennlist.
Nice color choice, enjoy it in good health and welcome in rennlist.
the 0881 should have Ascot instead, no?
07-07-2007, 10:55 PM
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Originally Posted by scaric
20C4S,
Yes its Polar Silver, one of two I am told.
Yes its Polar Silver, one of two I am told.
#884. My father's. Been wondering if there was another Polar CGT out there. Small world. 
Oh, welcome to Rennlist!
07-08-2007, 07:52 AM
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Originally Posted by scaric
TB, seems that you have all the bases are covered here. You are right, something is not quite right. I will be at the factory in a few days (car is there for the annual service/warranty work and having the stone guard applied) and I shall ask the question on the off chance they might commit! Even at 32.42s, I bet you had fun though!
.
.
If you manage to speak to someone knowledgable could you also ask if the ECU software was changed at some point in the production run to make the hill start clutch actuation easier ? A few people have stated this as fact but I'm still not convinced
Blasting to 195mph is sooo much fun - here is a crappy in car vid shot from yesterday:
http://www.youtube.com/watch?v=ae2PAOMBSZ8
07-08-2007, 05:16 PM
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Originally Posted by TB993tt
Edit: Looking at the handbook acceleration diagram it seems that I am not hanging onto the gears quite as long as they do, but still not whole seconds worth of difference...
First is the launch. Starting from dead still at maximum thrust in the CGT requires lots of practice, very good coordination, and maybe some race-driver talent. Looking at the acceleration force curve, I can imagine a Carrera-GT-magician driver could shave 2 to 3 tenths off your start. Your time to cover the initial 60 feet looks long when compared to professional drag racers.
Second, each of your shifts seem to take about 7 tenths of a second to go from full power to off to full power. A factory driver instructed to minimize the time-to-speed measurements might power shift, or at least risk some gear box or clutch wear-and-tear to reduce the amount of time not on the throttle. I can easily imagine half a second per shift disappearing if the drive train were to undergo some nasty "durability testing".
I think I can imagine 2 to 2.3 seconds total improvement if one were to sacrifice some mechanical longevity that no sane owner would ever attempt but might be given the green light by a factory record run.
The other comments posted about using very light weight drivers, optimum fuel, perfect weather, etc. are all common techniques used by racers every day to improve results. One imagines that Porsche races enough to fully understand how to take advantage of every opportunity that presents itself. Other manufacturers would do no less, either.
I don't think your results mean Porsche lied about the capabilities of the Carrera GT. I think it suggests only that it may be impossible to improve on their performance testing numbers, no matter how much the CGT under test might be abused. They had lots of practice to hone their technique before they recorded their best run.
07-08-2007, 07:54 PM
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I have spent signficant driving time in 456MGT's beautful black Carrera GT over the last few days - this doesn't qualify me to comment perhaps but my impressions are:
- I KNOW that optimising the launch of the car would require tremendous skill combined with a total lack of mechanical sympathy. I suspect there may be MORE than a second on the combined time to be gained from that alone as the 0-100/160 kph times taken from the diagram look "slow" comparitively.
- Linked to the above I think that traction plays a critical part as the car accelerates all the way up to some 80mph. (yesterday I saw the TC intervening at a ridiculous 93mph!).... For this reason, tyre temperature/condition/pressure may play a significant part in gaining time in the lower speed section of the diagram.
- Like W8MM stated in his excellent post - power shifting will gain you some 0.5s per shift - maybe more = 2.5s gain.
More to the point I have never known Porsche to lie about performance figures or BHP figures. If anything they have understated them.
My old 996 GT3RS dynoed 404hp after Porsche quoted 381hp and given that I have followed every test of this and the normal Mk2 GT3, they have ALL outperformed the factory quoted figures for 0-60mph and 0-100mph.
BTW, the 102 Octane juice from BP is ROCKET FUEL. In my 996RS, it made an enormous difference. It really did. 456MGT put some into the Carrera GT yesterday... the problem is, the cars performance is already on such a ridiculous plane that it's really difficult to notice improvement when you're totally overwhelmed by the performance of the car with the standard Shell V-Power petrol.
- I KNOW that optimising the launch of the car would require tremendous skill combined with a total lack of mechanical sympathy. I suspect there may be MORE than a second on the combined time to be gained from that alone as the 0-100/160 kph times taken from the diagram look "slow" comparitively.
- Linked to the above I think that traction plays a critical part as the car accelerates all the way up to some 80mph. (yesterday I saw the TC intervening at a ridiculous 93mph!).... For this reason, tyre temperature/condition/pressure may play a significant part in gaining time in the lower speed section of the diagram.
- Like W8MM stated in his excellent post - power shifting will gain you some 0.5s per shift - maybe more = 2.5s gain.
More to the point I have never known Porsche to lie about performance figures or BHP figures. If anything they have understated them.
My old 996 GT3RS dynoed 404hp after Porsche quoted 381hp and given that I have followed every test of this and the normal Mk2 GT3, they have ALL outperformed the factory quoted figures for 0-60mph and 0-100mph.
BTW, the 102 Octane juice from BP is ROCKET FUEL. In my 996RS, it made an enormous difference. It really did. 456MGT put some into the Carrera GT yesterday... the problem is, the cars performance is already on such a ridiculous plane that it's really difficult to notice improvement when you're totally overwhelmed by the performance of the car with the standard Shell V-Power petrol.