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Re: Disappointed in 7th gear ratio for PDK
Quote:
Gnil said:
Does any one know the difference with PDK when in ' track mode ' ?
What does it change exactly ?
You mean Sports Plus mode...
From official press release:
"The second new function in the Sports Chrono Package Plus in conjuction with PDK is a special gearshift strategy for extremely sporting driving performance, offering the shortest possible gearshift together with shift points optimised for the race track.
Again, this function is activated by Sports Plus button, PDK immediately switching over to the fastest possible reaction and gearshift times.
Gears are now shifted within fcartions of a second, twice as fast as on the previous TIP S transmission, When shifting uo under full load, for example, the engine is reved up to the maximum speed with a brief overboost of power.
And to optimise performance when shifting down in overrun, the transmission automatically applies extra gas in between gears."
Re: Disappointed in 7th gear ratio for PDK
Very interesting! How does this "Brief Overboost of Power" occur with a non-turbo motor? Does it just allow further revving past 7,500 rpm? If so, this is not much of a benefit (since max power is achieved at 6,500 rpm) and would be totally unnecessary if the gears had been made closer together to take advantage of the 7 gears in PDK, instead of just tacking on an economy 7th gear ratio...
Re: Disappointed in 7th gear ratio for PDK
Quote:
Grant said:
Very interesting! How does this "Brief Overboost of Power" occur with a non-turbo motor? Does it just allow further revving past 7,500 rpm? If so, this is not much of a benefit (since max power is achieved at 6,500 rpm) and would be totally unnecessary if the gears had been made closer together to take advantage of the 7 gears in PDK, instead of just tacking on an economy 7th gear ratio...
I do not think that engine is reving more then 7500rpm. IMO it means that electronic is simply adding throttle bip of some kind during upshift as well. You CAN NOT rev it more then 7500rpm, even in Sport Plus mode...
Re: Disappointed in 7th gear ratio for PDK
Quote:
KresoF1 said:
IMO it means that electronic is simply adding throttle bip of some kind during upshift as well. You CAN NOT rev it more then 7500rpm, even in Sport Plus mode...
I do not see the benefit of a throttle blip during upshift with PDK, since the shifting is already seamless. Adding a blip would only make the shift jerky and would unsettle the car on the track, imho...
The only thing I can imagine (besides raising the rev limit) is changing the fuel/ignition mapping to provide a bit more power.
Re: Disappointed in 7th gear ratio for PDK
Quote:
KresoF1 said:
BUT, I can bet with you that shifts are not smooth at all in Sport Plus mode.
I hope Porsche does not make the shifting jerky just to make it "feel" faster like BMW did with their DCT, unless it actually improves performance. Otherwise, this is a performance negative and causes more wear on the drive components, imho...
Re: Disappointed in 7th gear ratio for PDK
Quote:
Grant said:Quote:
KresoF1 said:
BUT, I can bet with you that shifts are not smooth at all in Sport Plus mode.
I hope Porsche does not make the shifting jerky just to make it "feel" faster like BMW did with their DCT, unless it actually improves performance. Otherwise, this is a performance negative and causes more wear on the drive components, imho...
Again, I fully agree with you.
BTW, what do you think what version is faster around Ring-manual or PDK? In good driver hands...
Re: Disappointed in 7th gear ratio for PDK
Quote:
KresoF1 said:
BTW, what do you think what version is faster around Ring-manual or PDK? In good driver hands...
I think the PDK will be a little faster, due to some of the gear ratios (like 2nd and 3rd) being closer together and the lack of thrust interruption while upshifting...
Re: Disappointed in 7th gear ratio for PDK
Quote:
Grant said:Quote:
KresoF1 said:
BTW, what do you think what version is faster around Ring-manual or PDK? In good driver hands...
I think the PDK will be a little faster, due to some of the gear ratios (like 2nd and 3rd) being closer together and the lack of thrust interruption while upshifting...
Well... We will see since rumor is that Sport Auto will test manual for Supertest, NOT PDK. You know what that means...
BTW, VW Gold GTI and R32... Manual faster around Hockenheim then DSG versions... Almost 1s faster... In straight line acceleration DSG faster...
Re: Disappointed in 7th gear ratio for PDK
There has been some speculation that the only reason the GTR came close or beat 911 Turbo around Ring, and other tracks (see CAR, EVO etc.) has been the time saved on faster shift times. I.e. imagine how many times you shift around the West Circuit, let alone the Ring, then calculate the quicker shift times versus a manaual (think GTR is 100 ms vs. ...), and you suddenly have a large deficit to make up in your turbo.
Re: Disappointed in 7th gear ratio for PDK
Quote:
gw2009 said:
There has been some speculation that the only reason the GTR came close or beat 911 Turbo around Ring, and other tracks (see CAR, EVO etc.) has been the time saved on faster shift times. I.e. imagine how many times you shift around the West Circuit, let alone the Ring, then calculate the quicker shift times versus a manaual (think GTR is 100 ms vs. ...), and you suddenly have a large deficit to make up in your turbo.
Sorry , but that logic would only work in the way you imply if the manual Turbo were at a standstill every time the clutch is not engaged.
The PDK naturally has advantages due to uninterrupted power flow during gearshifts, but differences in "clutch-open" times cannot be converted one-to-one into lap time improvements.
Re: Disappointed in 7th gear ratio for PDK
Quote:
gw2009 said:
There has been some speculation that the only reason the GTR came close or beat 911 Turbo around Ring, and other tracks (see CAR, EVO etc.) has been the time saved on faster shift times.
Having the DSG on a turbocharged car is a bigger advantage, since it nearly eliminates turbo lag on the shifts (keeps the motor on the boost, since you never take your foot from the throttle and the power delivery is seamless and always loads the motor).
Jun 10, 2008 9:01:59 PM
- 69bossnine
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Jun 10, 2008 9:19:24 PM
- Crash
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Jun 11, 2008 1:23:12 AM
- davew (cincy)
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Re: Disappointed in 7th gear ratio for PDK
Quote:
intouch1 said:Quote:
davew (cincy) said:
Grant,
If I understand the double clutch correctly, the added weight is not just added, some of it is also rotating.
A question I have related to the double clutch, is how quickly you can downshift two gears...?
even gears are on 1 shaft uneven on another. you could shift directly from 7th to 3rd....
the rotating assembly is not heavier. the whole transmission is heavier due to the double set of gears involved. still, pdk is lighter than tiptronic.
I don't think you are right here - please correct me if I am wrong, but the double clutch has two clutches (more rotating mass) and two shafts (again, more rotates). Also, it is the two shafts that allow pre-selection of odd gears while driving in even, and vice-versa. This is where the shifting speed comes from. I expect an immediate downshift of two gears would require a (slightly) longer delay...? Anyone else??
Also, with two clutches (concentric?) one is much larger (diameter) than would normally be necessary...?
Jun 14, 2008 9:00:44 PM
- fritz
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Re: Disappointed in 7th gear ratio for PDK
Quote:
davew (cincy) said:Quote:
intouch1 said:Quote:
davew (cincy) said:
Grant,
If I understand the double clutch correctly, the added weight is not just added, some of it is also rotating.
A question I have related to the double clutch, is how quickly you can downshift two gears...?
even gears are on 1 shaft uneven on another. you could shift directly from 7th to 3rd....
the rotating assembly is not heavier. the whole transmission is heavier due to the double set of gears involved. still, pdk is lighter than tiptronic.
I don't think you are right here - please correct me if I am wrong, but the double clutch has two clutches (more rotating mass) and two shafts (again, more rotates). Also, it is the two shafts that allow pre-selection of odd gears while driving in even, and vice-versa. This is where the shifting speed comes from. I expect an immediate downshift of two gears would require a (slightly) longer delay...? Anyone else??
Also, with two clutches (concentric?) one is much larger (diameter) than would normally be necessary...?
Davew, intouch,
A PDK transmission has two concentric input shafts as well as two clutches, increasing weight - including rotating masses. It does, however, have only one gear-set per ratio, like a conventional manual tranny, not two sets of gears.
The shift mechanism is effectively a sequential system, so shifting down two gears would take longer than shifting down one gear. Shifting, for example, directly from one "odd" gear to another "odd" gear is not possible.
The two clutches are in tandem, not concentric, so the inner diameter of the larger one does not have to be larger than the outer diameter of the smaller one. The clutch attached to the outer concentric input shaft is slightly larger than that attached to the inner shaft to optimize packaging.
Jun 14, 2008 11:25:20 PM
- davew (cincy)
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Re: Disappointed in 7th gear ratio for PDK
Thank you sir. 
One further question, if I may.
I understand the concept of "preselection" but how does this happen during down-shift as well as up-shift...?
How does the controller (computer, whatever) know if I intend to move from third to fourth, or back down to second? Is it only truely accomplished while heading up through the gearing? Or does it assume shifting continuity (if I went down last time, assume down will happen again - accept, perhaps for first and seventh...)
OK, thinking too much here - but still would like to understand...
Or perhaps Porshe prefers to keep this level of detail under wraps.
One further question, if I may.
I understand the concept of "preselection" but how does this happen during down-shift as well as up-shift...?
How does the controller (computer, whatever) know if I intend to move from third to fourth, or back down to second? Is it only truely accomplished while heading up through the gearing? Or does it assume shifting continuity (if I went down last time, assume down will happen again - accept, perhaps for first and seventh...)
OK, thinking too much here - but still would like to understand...
Or perhaps Porshe prefers to keep this level of detail under wraps.
Jun 15, 2008 6:42:31 AM
- SoCal Alan
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Re: Disappointed in 7th gear ratio for PDK
It's probably based on rpm acceleration or deceleration. If zero or near-zero acceleration, it's probably based on rpm range. I.e., if you are at the low end of the rpm range, it we'll probably preselect a lower gear, and vice-versa. Pretty simple, actually.
Jun 15, 2008 2:43:29 PM
- Leawood911
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Re: Disappointed in 7th gear ratio for PDK
Quote:
davew (cincy) said:
Thank you sir.
One further question, if I may.
I understand the concept of "preselection" but how does this happen during down-shift as well as up-shift...?
How does the controller (computer, whatever) know if I intend to move from third to fourth, or back down to second? Is it only truely accomplished while heading up through the gearing? Or does it assume shifting continuity (if I went down last time, assume down will happen again - accept, perhaps for first and seventh...)
OK, thinking too much here - but still would like to understand...
Or perhaps Porshe prefers to keep this level of detail under wraps.
Now we are starting to see that all automatics are a compromise - the real measure of shift time is how long it takes for the described shift (or 4-1, 7-3 etc.)
I would guess that for highway passing the 7-3 would be used often.
Jun 19, 2008 4:04:06 AM
- davew (cincy)
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Re: Disappointed in 7th gear ratio for PDK
Alan,
Of course! Well said - now that you point that out it is obvious! Cool...
Leawood,
I don't think its necessarily as bad as all that. According to Fritz, you can't drop two gears instantly, but - for passing - you can anticipate the transition enough to make up for a longer delay. If your looking to pass, you probably aren't sitting in 7. I do drop 2 gears in my stick for that, but I think you could hover 1 gear above where you want be for the pass - while you wait for the window to open.
Track conditions could (occasionally) be a small compromise on this level too, but I suspect that the advantages of shortened power interruption, and continuous steering control outweigh that occasional loss.
Maybe a small compromise there, but not a deal-break to me.
I do understand why many here think the manual is more "at one with the machine" but I've used paddles a few times in the past and love them.
Of course! Well said - now that you point that out it is obvious! Cool...
Leawood,
I don't think its necessarily as bad as all that. According to Fritz, you can't drop two gears instantly, but - for passing - you can anticipate the transition enough to make up for a longer delay. If your looking to pass, you probably aren't sitting in 7. I do drop 2 gears in my stick for that, but I think you could hover 1 gear above where you want be for the pass - while you wait for the window to open.
Track conditions could (occasionally) be a small compromise on this level too, but I suspect that the advantages of shortened power interruption, and continuous steering control outweigh that occasional loss.
Maybe a small compromise there, but not a deal-break to me.
I do understand why many here think the manual is more "at one with the machine" but I've used paddles a few times in the past and love them.
Jun 19, 2008 5:54:45 AM
- CarlosF
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Re: Disappointed in 7th gear ratio for PDK
This was the only way to achieve EURO 5/etc. certification I'm afraid.
Sportscar manufacturers and especially SUV manufacturers will find it more and more difficult to certify their engines/cars in the future due to more restrictive environmental laws.
Sportscar manufacturers and especially SUV manufacturers will find it more and more difficult to certify their engines/cars in the future due to more restrictive environmental laws.
Re: Disappointed in 7th gear ratio for PDK
Quote:
RC said:
This was the only way to achieve EURO 5/etc. certification I'm afraid.
Sportscar manufacturers and especially SUV manufacturers will find it more and more difficult to certify their engines/cars in the future due to more restrictive environmental laws.
Thanks, RC! Do you expect a different perforance-oriented gearstack with the GT models, since they have limited production or will they be subject to the same regulations?
Jun 21, 2008 10:22:44 AM
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Reply to:
RC
PDK in Sport Plus mode...
Hi RC!
A couple of additional observations regarding the "7-speed" PDK in Sport Plus mode...
1) "In Sport Plus mode the PDK gearbox locks out 7th gear, operating within gears 1-6 for ultimate performance driving..."
2) "In Sport Plus mode the 'power boost' from the PDK gearbox is subject to G-sensors that check whether the car is cornering hard, in which case the power boost will NOT be executed during a gear change to prevent destabilisation of the car during high-speed cornering..."
Apparently the "power boost" from PDK in Sport Plus mode is more about "emotion" than performance...
Also agree with Grant: the question now is how Porsche will adapt the PDK philosophy for track driving in the GT3... do we get a 7-speed close ratio performance PDK gearbox, with race-car "paddles"? Do we get to keep enjoying a race-developed GT1-based engine block, with or without Direct Injection?
Cheers!
GTS
PS: Thanks to Chris Harris for feedback on the PDK!
A couple of additional observations regarding the "7-speed" PDK in Sport Plus mode...
1) "In Sport Plus mode the PDK gearbox locks out 7th gear, operating within gears 1-6 for ultimate performance driving..."
2) "In Sport Plus mode the 'power boost' from the PDK gearbox is subject to G-sensors that check whether the car is cornering hard, in which case the power boost will NOT be executed during a gear change to prevent destabilisation of the car during high-speed cornering..."
Apparently the "power boost" from PDK in Sport Plus mode is more about "emotion" than performance...
Also agree with Grant: the question now is how Porsche will adapt the PDK philosophy for track driving in the GT3... do we get a 7-speed close ratio performance PDK gearbox, with race-car "paddles"? Do we get to keep enjoying a race-developed GT1-based engine block, with or without Direct Injection?
Cheers!
GTS
PS: Thanks to Chris Harris for feedback on the PDK!
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