W8MM
I am coming at this from someone who has always appreciated that Porsche acceleration numbers were ALWAYS conservative. Maybe you are too young to remember that ?
If Porsche said 0-60 in 5s it was always less......
They appeared to have changed that philosophy recently, I noticed quite a few weights being quoted which were never quite matched by road going vehicles.
As an old fashioned Porsche enthusiast, I don't like this trend.

I did not start from a dead stop. I have no desire to wreck my drivetrain. I started at ~30mph in 2nd gear and ran up through the gears ( not once, data logged 7 times ), There was no wheelspin or TC activation in second gear as the car went through 100kph -the start is not the issue here there are NO traction issues, I simply used ~3.8s 0-100kph and added it to the 100-300kph time....
As for the shifts. They were pretty good I think. All under 0.6s one at 0.3s. Yes "power shifting" may give better numbers but still, powershift X 4 = what 1.5s saving maximum ??
Sauron
I agree that the 102 may make a difference but firstly I would say that Porsche have always used pump fuel in their published numbers so surely "loopy juice" should not be an option ? And secondly, having measured the difference (in a high HP turbo Porsche ) between 102BP and Shell V Power99 it is not worth full seconds......
Porsche's acceleration diagram is at least 4 seconds out ?

 

Not to beat a dead horse but from your other posts, people are giving you a bunch of reasons why your numbers were under Porsches claim and you seem to discount them and state that they don't give you the 5 seconds.

I have seen pro drag strip guys able to get a full second better times than a better than average driver in a quarter mile.

Your shifts look like they are very slow to me, I don't see anywhere where you had a .3 seconds shift. I believe you are giving up at least 2.5 - 3 seconds with your shifting. You also stated that you had two people in the car and are running a car with half a tank of fuel and AC, etc... Porsches "test" car was probably 300-400 pounds lighter than your car without the parasitic drag of the AC. I would also guess that they tested the car on a cooler day where the car was making more horsepower. I have seen magazines getting better times than Porsches claim of 3.8 seconds for 0-100 kph so you are probably adding in another .5 seconds.

So I believe with a great driver who doesn't care about how much he trashes the car, a single driver, no AC, almost empty tank, cool day, etc... I believe the car did run in the 27's. Porsche would be very foolish to publish this number and not have video or some other way to prove their claim.

I also don't believe that the average driver can attain this number with a stock car with AC, normal temps, etc...

Do I blame Porsche for providing numbers that aren't realistic in the real world, yes and no. Yes because when they state numbers you hope that a stock car could duplicate their effort, no because Porsche has to compete with other car manufacturers who skew their results also.

I envy you having the oportunity to take the car upto those speeds legaly and relatively safely. I hope you took the car to 200mph at least once though! I want to join the 200mph club but I haven't had the chance to do it in a safe environment like you had.

 

Marsman, from seeing many datalogged runs from TB993TT I can guarantee you that a factory test driver would not shift much faster than he does, probably a 1/10th or so if powershifting.

As he said, this graph shows a rolling start, therefore launch variables are excluded. A 1 second difference in time during a quartermile run is very little in comparison with a 1 second difference at 300KPH.

Some other variables, weight has "some" impact over acceleration at high speed levels, but much less than a 0-200kph for instance, and gives way to aerodynamic drag and downforce...a CGT at 300kph will be fighting a drag of ca. 400BHP equivalent.

The way to look at this is that a factory published 0-200kph of 9.9 seconds means a 200-300kph (124-186mph) in about 17 seconds. While looking at TB993TT's numbers, the 124-186mph time was about 21.2 seconds (reading from the graph), and there are 2 gear changes involved only. In a 200-300KPh run, a 200lbs difference would represent about 0.8 seconds.

The difference between factory numbers and TB's numbers over the 124-186mph run is 4.1 seconds, about a quartermile in distance terms! These numbers are validated by Sport Auto as well, so I would exclude a problem in TB's car most likely.

Quite surprising coming from Porsche indeed.

 

Is this not what the RL Tech forums are for ?
All owners on here KNOW we own the best cars in the world, there is no argument there, but there is a big discrepancy here and those of an enquiring persuasion would like answers...
I hope I haven't "discounted" others' answers, please lets keep talking about this

Firstly, as I stated in an earlier post, the A/C was OFF (and it was bloody hot in there )
I know it is pretty difficult to see the shift duration from the graph, but the shifts were pretty good and as Jean points out above the 200-300kph element takes only 2 shifts yet is ~4s slower...

.I have to say that with the blind belief from a few CGT owners, why would Porsche be foolish ? It seems that a big proportion of their customers want to believe what they are told

.I take your point here but it is a change in direction for Porsche, they used to always be the masters of understatement and it was always great to watch the magazines go out and beat Porsche's conservative numbers every time....
.Believe me I tried for the 200 but there just wasn't enough room, the aero drag over 180 really slows the car down - here is a really bad video taken from the CGT - if you see the car shown running alongside is LeonS's RT12. I start off before him but as I go through the timing beam (you will see some red bollards) the RT12 has caught up and crosses the line at 203mph compared to the CGT 193mph
http://www.youtube.com/watch?v=ae2PAOMBSZ8

 

TB many thanks for the ride in the GT on Saturday - a very special experience, thank you. I will try to upload the videos of you running with MOD in the week.

The stability at speed was very impressive.

One question/thought - the rear wing element that raises on the GT - is this always up whilst moving? Could porsche have run with it in the lower setting for the full 0-300?

Cheers Rich

 

Ruxpin
It was great fun wasn't it

The wing theory is a good one. Hopefully we should have some more concrete information on this topic next week.
Here is the same graph but easier to see the 100-300kph:

 

I was at Gross Dölln one time - the CGT was being thrashed

how about - left foot rotated sideways at start and then not used again until it was all over. I wasn't in the car, I was up to other evilness, but that is what it sounded like.

That would save 2.5+ on the changes, this was an early car, so who knows what the TC was like, the take off was lethal and the smell was addictive.

I went back to destroying tyres with a grin.

R+C

 

icon
Thank for trimming the graphs - I should learn how to do that
The CGT feels nothing short of savage at all speeds, I just have a penchant for the truth in these sorts of things....Normally it is tuners who exaggerate.
I have always liked the 300kph acceleration tests as they sort the cars with real power from the pretenders -it was the Sport Auto test which piqued my interest in the CGTs numbers.
The straight line stuff is a lot of fun but there were also a couple of corners involved
If marsman is right and they have resorted to other means - like Nordschleife says, clutchless gear changes and also extra light weight and maybe special fuel, no rear wing...... This is fine and fair, just want to know.

Like I said, a new RLer is going to get some "hot" info for next week

 

TB,
The next time you go for an acceleration run try resetting the ME7.1.1 ECU adaptation values after a few runs and see if that makes a difference.

 

How would someone go about doing this?

 

A Porsche System Tester 2 or PiWiS should be able to do it. I'm not sure about Durametric.

 

Disconnect the battery.

 

I thought the adaptation values were stored in EEPROM?

 

Interesting, it is correct that Porsche was very conservative with their times and BHP, it would be a shame if this wasn't the case now, but as we know accountants are now designing the engines at Porsche just look at the 996 (except GT3) so we all should know how creative these people are with figures, let's not dwell too much on the all the accounting scandels that rocked Wall street about five years ago but maybe it has caught on at Stutgart?

Given some of the BIG dyno numbers that have been posted on this forum (on American manufactured dynos) I think we should all be a bit sceptical of some claims. Thanks to all those who question before believing/accepting information.

Greg

 

Scaric (assuming you are still around ) any chance getting some info from the factory when you were there? We still did not put this to bed.