Jan 23, 2013 4:59:57 PM
- nberry
- Rennteam VIP
- Loc: La Jolla, USA , United States
- Posts: 13737, Gallery
- Registered on: Apr 11, 2002
- Reply to: davew (cincy)
Jan 23, 2013 4:59:57 PM
Jan 23, 2013 5:04:35 PM
Grant:
MKSGR:
davew (cincy):
Very true. I'm not sure how much slowing occurs in a fraction of a second, but I'm sure you are at least right in principle!
The strange thing is that the car can loose like 5-10kph (!) during these high-speed shifts (relative to N/A car with F1 transmission)
That number is based on the Turbocharged GT2 that falls out of maximum boost, right? No way that happens with a normally aspirated motor...
Of course deceleration during the shift would not be affected by NA versus turbo, but you make a strong point for the shifting effect on a GT2 or Turbo. When PDK is available on those cars, it should be very significant.
Honestly, I doubt that the deceleration is as significant as this, but my calcs at least show that, even in this debatable case, the shift delay does not add second-for-second to lap time.
Here's the video I used:
http://www.youtube.com/watch?v=R4JXiGFJI5I
I don't see any real drop in speed between shifts here. And the shifting is not perfect or consistent each time. Of course, the speedo needle is probably not that time-responsive either. Don't even bother trying to use the digital display - its way slow...
Jan 23, 2013 5:14:50 PM
davew (cincy):
Grant:
MKSGR:
davew (cincy):
Very true. I'm not sure how much slowing occurs in a fraction of a second, but I'm sure you are at least right in principle!
The strange thing is that the car can loose like 5-10kph (!) during these high-speed shifts (relative to N/A car with F1 transmission)
That number is based on the Turbocharged GT2 that falls out of maximum boost, right? No way that happens with a normally aspirated motor...
Of course deceleration during the shift would not be affected by NA versus turbo, but you make a strong point for the shifting effect on a GT2 or Turbo. When PDK is available on those cars, it should be very significant.
Honestly, I doubt that the deceleration is as significant as this, but my calcs at least show that, even in this debatable case, the shift delay does not add second-for-second to lap time.
Here's the video I used:
http://www.youtube.com/watch?v=R4JXiGFJI5I
I don't see any real drop in speed between shifts here. And the shifting is not perfect or consistent each time. Of course, the speedo needle is probably not that time-responsive either. Don't even bother trying to use the digital display - its way slow...
Right - the loss of 5 or 10 kph won't happen over the .3 sec shifting window - it could only happen over the longer period of resuming acceleration and respooling full boost, relative to a car on full boil (no actual loss of that much velocity). Even then, seems exaggerated to me. Non-turbo cars will not display anything like this behavior.
73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs). Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550 Maranello
Jan 23, 2013 5:24:40 PM
nberry:
You are human the computer is not.
Very true, earthling, very true.
Of course its not just the weight of the vehicle, its the mass of the rotating components in the comparable transmission that matters even more. And I think the PDK approaches double on that score.
Lots of things would effect the validity of the calcs I did, honestly. I'm not even sure if the PDK uses the same gear ratios, and that would make a huge difference in specific scenarios.
I just wanted to help illustrate that the elimination of a momentary power loss during the shift does not effect lap time on a second-for-second basis, as Grant noted.
Either way, a 6 to 10 foot gain during a mid range shift-point could be HUGE in a competitive event, so PDK surely has its implications.
Grant:
MKSGR:
davew (cincy):
Very true. I'm not sure how much slowing occurs in a fraction of a second, but I'm sure you are at least right in principle!
The strange thing is that the car can loose like 5-10kph (!) during these high-speed shifts (relative to N/A car with F1 transmission)
That number is based on the Turbocharged GT2 that falls out of maximum boost, right? No way that happens with a normally aspirated motor...
Exactly, a 997 GT2 (530hp)
BTW, the full data protocol of the test (GT2 manual vs. 430 Scuderia F1) can be found here:
http://www.rennteam.com/forum/thread/20498151/Re_GT3_RS_40/page1.html
The blue line is the GT2 - with the speed dropping at high-speed shifts.
check out the porsche web-pages and compare the models which have manual vs PDK column and with the 991 4S to 160 km/h it's already 0.4 second and I am sure the manual time is done with their best efforts too. this is a simple indication. Add a normal Porsche driver to it and the gap would still go higher. I believe there is a big difference in pure theoretical numbers vs reality.
BjoernB:
check out the porsche web-pages and compare the models which have manual vs PDK column and with the 991 4S to 160 km/h it's already 0.4 second and I am sure the manual time is done with their best efforts too. this is a simple indication. Add a normal Porsche driver to it and the gap would still go higher. I believe there is a big difference in pure theoretical numbers vs reality.
RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), BMW X3 35d (2012), Mini Cooper S Countryman All4
RC:
BjoernB:
check out the porsche web-pages and compare the models which have manual vs PDK column and with the 991 4S to 160 km/h it's already 0.4 second and I am sure the manual time is done with their best efforts too. this is a simple indication. Add a normal Porsche driver to it and the gap would still go higher. I believe there is a big difference in pure theoretical numbers vs reality.
I think most of that advantage comes from launch control and won't translate to laptime on a road course.
73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs). Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550 Maranello
I can't help from putting in my 2 cents here.
Not having to make decisions to shift is a bigger deal to me than others. It can be counter intuitive. Two brothers who both race are friends of mine. One of them is faster in their Cup car than the other. At a track near Indianapolis, the slower one shifts 8 times driving the track. The faster one shifts 14 times driving the same track in the same car and is 2 seconds per lap faster. A huge difference on a track that laps 1 minute 12 seconds at the front of the pack. In their 944 race car, there is much less difference between the two drivers in lap times.
So, making the decision NOT to shift in order to make a cornering maneuver easier to complete or a corner entry more stable (higher entry speed) is a big deal in track driving. I know I have left seconds per lap on the table because I was worried that a less-than-perfect down-shift might upset the car on entry to the coming corner. What if I don't get it done in time or smoothly enough? So, I don't shift up and just cruise for a short distance at red-line before braking for the next corner.
If PDK would guarantee that my down shifts are all perfect, I would up-shift between those corners and gain some more speed, instead of floating along in a lower gear to prevent a possibly upsetting subsequent down-shift. With ME behind the wheel, PDK seems faster for sure.
--
Mike
Carrera GT + Tesla Roadster 1.5 + Panamera Turbo + BMW Z8 + BMW 3.0 CSi + Bentley Arnage T + GT3 RS 4.0
W8MM:
If PDK would guarantee that my down shifts are all perfect, I would up-shift between those corners and gain some more speed, instead of floating along in a lower gear to prevent a possibly upsetting subsequent down-shift. With ME behind the wheel, PDK seems faster for sure.
--
Mike
Carrera GT + Tesla Roadster 1.5 + Panamera Turbo + BMW Z8 + BMW 3.0 CSi + Bentley Arnage T + GT3 RS 4.0
and with PDK you can actually even shift in the corner, the car will not get upset as everything is done smoothly
997.2 C2S, PDK, -20mm
Jan 24, 2013 9:14:31 PM
Jan 24, 2013 9:54:18 PM
I pray that people flock to the 991GT3, so I can pick up a 3.8 or 4.0 RS with its antiquated and slow gearbox on the cheap! Those cars will be classics.
73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs). Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550 Maranello
Jan 25, 2013 1:48:36 AM
BjoernB:
check out the porsche web-pages and compare the models which have manual vs PDK column and with the 991 4S to 160 km/h it's already 0.4 second and I am sure the manual time is done with their best efforts too. this is a simple indication. Add a normal Porsche driver to it and the gap would still go higher. I believe there is a big difference in pure theoretical numbers vs reality.
This may sound like techno-babble, but that doesn't really conflict with my calcs at all...!
I'll try to explain:
Grant's point (and my supporting calcs) were done with regard to lap time - which is the amount of time required to travel a certain DISTANCE.
In a 0-100mph comparison, you are looking at the amount of time to acquire a specific SPEED. Which in the case of the PDK transmission car (with essentially continuous acceleration) actually occurs sooner on the track (in a shorter distance). So this is not a finish line, distance-based, or lap time - comparison. In fact, if the cars accelerate identically (or nearly so) during the time that they are actually in gear, the difference in time here is almost completely the shifting delay (of actually two shifts I believe to acquire 100mph) adding second-for-second in this kind of comparison. In fact, these numbers are a little closer together than maybe they should be - the manual driver must have shifted very well, and launched pretty impressively.
I'm not sure if I can adequately express this, but your spec information is actually exactly what we should expect; theoretical, and in reality...
Again, I am not trying to imply that PDK is anything but better (performance wise) than manual at this point. I'm just trying to show that the sum of removed shift delays is not identical to the improvement in lap time.
Jan 25, 2013 2:10:35 AM
W8MM:
I can't help from putting in my 2 cents here.
Not having to make decisions to shift is a bigger deal to me than others. It can be counter intuitive. Two brothers who both race are friends of mine. One of them is faster in their Cup car than the other. At a track near Indianapolis, the slower one shifts 8 times driving the track. The faster one shifts 14 times driving the same track in the same car and is 2 seconds per lap faster. A huge difference on a track that laps 1 minute 12 seconds at the front of the pack. In their 944 race car, there is much less difference between the two drivers in lap times.
So, making the decision NOT to shift in order to make a cornering maneuver easier to complete or a corner entry more stable (higher entry speed) is a big deal in track driving. I know I have left seconds per lap on the table because I was worried that a less-than-perfect down-shift might upset the car on entry to the coming corner. What if I don't get it done in time or smoothly enough? So, I don't shift up and just cruise for a short distance at red-line before braking for the next corner.
If PDK would guarantee that my down shifts are all perfect, I would up-shift between those corners and gain some more speed, instead of floating along in a lower gear to prevent a possibly upsetting subsequent down-shift. With ME behind the wheel, PDK seems faster for sure.
--
Mike
Carrera GT + Tesla Roadster 1.5 + Panamera Turbo + BMW Z8 + BMW 3.0 CSi + Bentley Arnage T + GT3 RS 4.0
Great point! Its encouraging to hear a driver of your experience level say all that!
Jan 25, 2013 4:15:27 PM
Jan 25, 2013 4:35:44 PM
Leawood911:
Timo seemed a little slow in the approach to a few sections. Interesting how the 4.0RS did not have sport chrono (of all the Porsches that could use it). Perhaps there was one wart too many in the car. (could not resist)
7.2 GT3/RS/4.0 Sport Chrono does not give the option of a different engine or PSM mapping. It's only for timing and some memory functions
Jan 25, 2013 5:16:24 PM
davew (cincy):
W8MM:
I can't help from putting in my 2 cents here.
Not having to make decisions to shift is a bigger deal to me than others. It can be counter intuitive. Two brothers who both race are friends of mine. One of them is faster in their Cup car than the other. At a track near Indianapolis, the slower one shifts 8 times driving the track. The faster one shifts 14 times driving the same track in the same car and is 2 seconds per lap faster. A huge difference on a track that laps 1 minute 12 seconds at the front of the pack. In their 944 race car, there is much less difference between the two drivers in lap times.
So, making the decision NOT to shift in order to make a cornering maneuver easier to complete or a corner entry more stable (higher entry speed) is a big deal in track driving. I know I have left seconds per lap on the table because I was worried that a less-than-perfect down-shift might upset the car on entry to the coming corner. What if I don't get it done in time or smoothly enough? So, I don't shift up and just cruise for a short distance at red-line before braking for the next corner.
If PDK would guarantee that my down shifts are all perfect, I would up-shift between those corners and gain some more speed, instead of floating along in a lower gear to prevent a possibly upsetting subsequent down-shift. With ME behind the wheel, PDK seems faster for sure.
--
Mike
Carrera GT + Tesla Roadster 1.5 + Panamera Turbo + BMW Z8 + BMW 3.0 CSi + Bentley Arnage T + GT3 RS 4.0
Great point! Its encouraging to hear a driver of your experience level say all that!
As a counterpoint, I have never changed my shifting strategy based on worry of upsetting the balance of the car - always pursued a strategy based on fastest laptime. If that requires perfecting my shifting and rev-matching to avoid shunting the car, I relish the opportunity to improve my driving. I find this one of the most rewarding aspects of track driving (note: no ABS, TC, or PSM while using the most tricky Porsche 915 gearbox that frequently requires double-clutch heel-toe techniques). Different strokes for different folks...
--
73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs). Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550 Maranello
Jan 25, 2013 7:47:41 PM
Grant:
Same with 997.1 and GT2. No GT model has ever has a performance benefit from SC.
Interesting Grant - on 2-24-2006 you stated this on Rennlist - (which is true) - and some think I don't read.
"According to reliable sources on Rennteam, there will be a "Sport" button with the Sport Chrono option that not only increases throttle pedal sensitivity (like on the 997/S), but also increases power and torque (25 Newton-Meters) in the midrange:
"This means that with the powerboost, the new GT3 not only has more torque between 3000 rpm and 4200 rpm but also slightly more power (compared to the power within this rev range, not compared to maximum power output!). "
Peak torque is increased to 405 Nm.
So, make sure you don't skip this option, even if you hate the little stopwatch on the dashboard...
I imagine that this better mid-range performance is only the result of better engine mapping with the ECU (which is sort of gimmicky imho), but seems like a must have option, since the other cars will be hamstrung without it...
There is also a similar feature on the new Turbo where the Sport button allows more boost for 10 secs at lower rpm for 10% more torque below 4,000 rpm."
Could not resist - by the way, the wart thing was a joke. Did you not see the thing on his face? Never mind.
Jan 25, 2013 7:50:15 PM
Grant:As a counterpoint, I have never changed my shifting strategy based on worry of upsetting the balance of the car - always pursued a strategy based on fastest laptime. If that requires perfecting my shifting and rev-matching to avoid shunting the car, I relish the opportunity to improve my driving. I find this one of the most rewarding aspects of track driving (note: no ABS, TC, or PSM while using the most tricky Porsche 915 gearbox that frequently requires double-clutch heel-toe techniques). Different strokes for different folks.
Grant,
I'll bet you're not 6'4" with 36" inseams.
In my old '74 IROC 911RS, I had plenty of foot-box room to rotate my lower legs and feet into any contortive position I needed. I was fast and confident with my foot work. In the Carrera GT, there is almost enough room to be dexterous during heel-and-toe maneuvers. In the RS 4.0, there is not enough foot/leg flexibility room for me to be very confident during combinations of high-g conditions that press on ones body parts while trying overlapping control inputs. It's too damned cramped for it.
I'm still the same size I always was, but Porsches seem to get ever tighter where my shins bang into center consoles, etc..
Mike
Carrera GT + Tesla Roadster 1.5 + Panamera Turbo + BMW Z8 + BMW 3.0 CSi + Bentley Arnage T + GT3 RS 4.0
W8MM:
Grant:As a counterpoint, I have never changed my shifting strategy based on worry of upsetting the balance of the car - always pursued a strategy based on fastest laptime. If that requires perfecting my shifting and rev-matching to avoid shunting the car, I relish the opportunity to improve my driving. I find this one of the most rewarding aspects of track driving (note: no ABS, TC, or PSM while using the most tricky Porsche 915 gearbox that frequently requires double-clutch heel-toe techniques). Different strokes for different folks.
Grant,
I'll bet you're not 6'4" with 36" inseams.
In my old '74 IROC 911RS, I had plenty of foot-box room to rotate my lower legs and feet into any contortive position I needed. I was fast and confident with my foot work. In the Carrera GT, there is almost enough room to be dexterous during heel-and-toe maneuvers. In the RS 4.0, there is not enough foot/leg flexibility room for me to be very confident during combinations of high-g conditions that press on ones body parts while trying overlapping control inputs. It's too damned cramped for it.
I'm still the same size I always was, but Porsches seem to get ever tighter where my shins bang into center consoles, etc..
I am 6' with very long torso and tiny legs (30" or less inseam). I have plenty of room for the pedals, but often run out of headroom in most cars
I can understand where having no center console would be helpful for my long-legged brothers
--
73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs). Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550 Maranello
Jan 26, 2013 5:24:06 PM
Boxster Coupe GTS:
Porsche 911 GT3 RS 4.0 driven by Timo Kluck...
"FAST AS HELL"
...turn up the volume...
...reportedly the new Porsche 991 GT3 and GT3 RS will be available with Michelin and Dunlop tyres...
Perhaos the more experienced racing drivers could explain - does it look like the 997 RS is more tricky to handle at the limit as in Timo's video? From what I have read the 991 chassis is much better on the limit and easier to control than this.
boytronic:Perhaos the more experienced racing drivers could explain - does it look like the 997 RS is more tricky to handle at the limit as in Timo's video? From what I have read the 991 chassis is much better on the limit and easier to control than this.
Surely the definition of "limit" in this context is that it is getting tricky to handle?
When comparing different models its a question of where their respective limits lie.
fritz
I thought the car handled magnificently. Granted the driver was top notch but at those speeds the car appeared glued to the road. Can't ask for more than that. A very impressive car.
But for the rough ride, I would not mind owning this car (though it would be a waste since I probably would not track it).
fritz:
boytronic:Perhaos the more experienced racing drivers could explain - does it look like the 997 RS is more tricky to handle at the limit as in Timo's video? From what I have read the 991 chassis is much better on the limit and easier to control than this.
Surely the definition of "limit" in this context is that it is getting tricky to handle?
When comparing different models its a question of where their respective limits lie.
I think it's easy to watch this video and be intimidated by the handling of the 4.0, but this car is a pussy-cat, imo. You are watching a professional driver extract almost 100% from it on the fastest/scariest of all road courses. Driving the car within the limits of most mortals on an average track is not a scary experience at all.
There is an enormous difference driving a car to its limit on a 75 mph bend as compared to a 120 mph bend.
--
73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs), 06 EVO9 with track mods. Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550