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      03-27-2008, 06:31 PM   #155
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Originally Posted by swamp2 View Post
They only really had x axis scales labeled with numbers. The y's having much more uncertainty. I did suggest two bets.

1. M-DCT under its fastest shifts will exhibit shift times shorter than 100 ms as defined by the period in a sufficiently accurate accelerometer trace from the initial point of deceleration to the resumption of acceleration (sharp-ish knee after shift).

2. Such acceleration curves will dip substantially less than MT or SMG curves on deceleration and will be capable of exhibiting shifts where the dip in acceleration will not go to negative acceleration values.

I agree with 2 so I won't bet there.

How about the MDCT will take >0.8 seconds to shift (me) and you bet the MDCT will take <0.8 seconds to shift in the fastest setting?
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      03-27-2008, 06:34 PM   #156
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I disagree with this in principle. You can have zero time to disengage one clutch and reengage another. There could be a period where both clutches are engaged. The new clutch would start out slipping while the old one was still fully engaged. Then the old would start slipping until it was fully disengaged. By the time the old clutch is fully disengaged the new one will be fully engaged. In between this time both clutches would be engaged while the engine is still on throttle. Throughout this whole period torque is being supplied and no loss of acceleration would be seen.

This is theoretical. I really don't know if M-DCT can do this. . I am assuming it will. But remember: in theory, theory and reality are always the same. In reality, they're not.

Care to wager on your theory?

Here is a hint, if both clutches were engaged at the same time, you would be in 2 gears simulataneously. There is some finite period where neither are engaged and you will slow down, no matter how slight.

What would you like to wager?
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      03-27-2008, 06:34 PM   #157
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Foot, you really are clueless. Did you watch the M6 SMG III video above? That car can break loose (just a bit) all the way into 5th gear with "only" 500 hp. What can 800 do, along with some boost from those turbos? I know the answer and in lower gears it would coule be really ugly (or fun depending on the driver...)

Sorry swamp I thought I made it clear that the Veyron was never getting a manual and always was intended to get DSG. Why keep discussing the SMG which is effectively a single clutch manual, the two gearboxes behave totally differently.

I recommend sampling the gearbox in the M3 before comparing it to the SMG in the M6.
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      03-27-2008, 06:35 PM   #158
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You still aren't explaining why BMW and Audi quote an identical improvement over their manual cars. Surely if you were right BMW would be quoting an even bigger improvement but the facts are they aren't.............why?

Maybe the difference is so small as to not make any noticeable difference at all and that is what the guys is meaning, who knows. Only when both systems are tested together will we see for sure.
Well, BMW quoted 0 - 60 in 4.7 seconds for the coupe. We've seen reviewers get much better than that. Maybe BMW is just being conservative with their numbers again.
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      03-27-2008, 06:37 PM   #159
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I wish you guys would stop talking about Bugatti. I am not in the market for one at this time.
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      03-27-2008, 06:41 PM   #160
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Quote:
Originally Posted by ersin View Post
Well, BMW quoted 0 - 60 in 4.7 seconds for the coupe. We've seen reviewers get much better than that. Maybe BMW is just being conservative with their numbers again.
And I know for a fact that the DSG improves more than the 0.2s be in quoted. Sure it's just a figure but it's funny BWM choose to use Audi's figures, no.
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      03-27-2008, 06:46 PM   #161
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Quote:
Originally Posted by ersin View Post
I disagree with this in principle. You can have zero time to disengage one clutch and reengage another. There could be a period where both clutches are engaged. The new clutch would start out slipping while the old one was still fully engaged. Then the old would start slipping until it was fully disengaged. By the time the old clutch is fully disengaged the new one will be fully engaged. In between this time both clutches would be engaged while the engine is still on throttle. Throughout this whole period torque is being supplied and no loss of acceleration would be seen.

This is theoretical. I really don't know if M-DCT can do this. . I am assuming it will. But remember: in theory, theory and reality are always the same. In reality, they're not.
+1. This is exactly the theory and what is explained in the big technical press release on M-DCT. Posted long ago, but put here again for ease/clarity.
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File Type: pdf mdctinfo.pdf (185.0 KB, 48 views)
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      03-27-2008, 06:51 PM   #162
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Quote:
Originally Posted by T Bone View Post
Care to wager on your theory?

Here is a hint, if both clutches were engaged at the same time, you would be in 2 gears simulataneously. There is some finite period where neither are engaged and you will slow down, no matter how slight.

What would you like to wager?
Two gears engaged simultaneously: that's right! The key point is that they are not FULLY engaged simultaneously.

Tell me how you intend to measure this, then I'll tell what I'll wager. Or how about this: if it can proven that M-DCT always results in deceleration during shifting, then I will get a 6MT, otherwise I will get a DCT M3?
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      03-27-2008, 06:52 PM   #163
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Quote:
Originally Posted by footie View Post
Sorry swamp I thought I made it clear that the Veyron was never getting a manual and always was intended to get DSG. Why keep discussing the SMG which is effectively a single clutch manual, the two gearboxes behave totally differently.

I recommend sampling the gearbox in the M3 before comparing it to the SMG in the M6.

Yes, sorry, I thought you meant a MT would not spin effortlessly in the Veyron. That probable misunderstanding produced my last insult. Sorry! You meant that a BMW-ish DCT in the Veyron with the surge/jerk as per my and enigmas views would not be sufficient to cause major traction problems, right? I think I agree with that. I suspect why they did not choose the option is the cars marketing goal of something very smooth and very driveable.
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      03-27-2008, 06:53 PM   #164
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Quote:
Originally Posted by ersin View Post
Two gears engaged simultaneously: that's right! The key point is that they are not FULLY engaged simultaneously.

Tell me how you intend to measure this, then I'll tell what I'll wager. Or how about this: if it can proven that M-DCT always results in deceleration during shifting, then I will get a 6MT, otherwise I will get a DCT M3?

If I am right, there will be a sharp spike down between gear shifts. If you (and Swamp2) are right, the G curve will just decrease over time smoothly (as you run through the gears) and the G you would feel decreases as torque to the wheels decreases.

Care to wager then?
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      03-27-2008, 06:56 PM   #165
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The more I read that the more I believe that the surge was engineered to provide as they say themselves 'truly sporting experience all of the time', no other reason.
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      03-27-2008, 07:01 PM   #166
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The more I read that the more I believe that the surge was engineered to provide as they say themselves 'truly sporting experience all of the time', no other reason.
Maybe it was engineered to be 'truly sporting' but you have to agree that there is a benefit, even if small, in making use of the rotational energy between gears so that a performance and an efficiency benefit will be realized -- one that can presumably be measured (with proper gear) as well as felt.

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      03-27-2008, 07:08 PM   #167
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Care to wager then?
I know this was not a reply to me but I already suggested 2 bets. Ball is in your court.
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      03-27-2008, 07:11 PM   #168
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Quote:
Originally Posted by ersin View Post
Maybe it was engineered to be 'truly sporting' but you have to agree that there is a benefit, even if small, in making use of the rotational energy between gears so that a performance and an efficiency benefit will be realized -- one that can presumably be measured (with proper gear) as well as felt.

This is why I wrote this

Quote:
Originally Posted by footie
Maybe the difference is so small as to not make any noticeable difference at all and that is what the guy's meaning, who knows. Only when both systems are tested together will we see for sure.
But if he says it has no real benefit to performance then that is good enough for me.

I also said I may test the DCT and love this surge, who knows but that wasn't the argument, the argument was always that some believe it is making a noticeable difference to the acceleration, why else would BMW included and I say it's there only for those SMG customers and nothing more.

I wonder if the lateness of reviews starting to come about are down to finalising the characteristics/behave of the shifts. Maybe an eleventh hour rethink was performed, the gearbox was sampled by SMG customers and they didn't like the smoothest of the original setup. Who knows.
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      03-27-2008, 07:15 PM   #169
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I wonder if the lateness of reviews starting to come about are down to finalising the characteristics/behave of the shifts. Maybe an eleventh hour rethink was performed, the gearbox was sampled by SMG customers and they didn't like the smoothest of the original setup. Who knows.
Aha, so that's why the Elektra was recalled! Conspiracy!
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      03-27-2008, 07:26 PM   #170
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I think many have not read or have forgotten this BMW document. Some quotes below. Again I criticize BMW marketing about as much as any but let's look at what they say and until we know otherwise, take it at face value. They can be sued for false advertising if the facts are too blatantly incorrect. The quote that says shifts occur in milliseconds may be a target here...

Quote:
To provide an even more sporting driving impression and to further improve the carís acceleration ... The additional power generated
in this way comes out clearly in the new transmission ratio feeding torque and
traction to the drive wheels.
Conclusion: As we have been arguing. It feels faster and is faster due to the dump of flywheel momentum.

Quote:
the change in gears now taking place without the slightest interruption of power and torque.
Conclusion: There is no appreciable deceleration as there is no interruption of power.

Quote:
Precisely this is why the indicator needle in the rev counter is virtually the only sign of a change in gears when shifting in the automated mode. The load change reactions so typical of a conventional gearbox are avoided completely, ensuring a standard of driving comfort even under dynamic conditions never experienced before.
Conclusion: Automatic mode is going to be darn good and very comfortable.

Quote:
The driving programs differ through the speed at which they change gears as well as the engine revs at which a gearshift is initiated. Both of these parameters are varied in all driving programs as a function of current driving conditions, the speed of the car, and the position of the gas pedal.
Conclusion: Despite some comments (both SteveD and footie) the shift times WILL vary, period.
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      03-27-2008, 07:32 PM   #171
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I know this was not a reply to me but I already suggested 2 bets. Ball is in your court.

My counter yes or no? Considering you don't think there will be spikes, this should be a slam dunk win for you.

Yes or no?
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      03-27-2008, 07:40 PM   #172
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My counter yes or no? Considering you don't think there will be spikes, this should be a slam dunk win for you.

Yes or no?
Nope, that is not it. Read my posts and proposal for a bet. I am betting on little to no downwrd spike on leading edge of the shift. This is totally independent as to whether or not you feel the jerk on shifts.
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      03-27-2008, 07:43 PM   #173
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I wonder if the lateness of reviews starting to come about are down to finalising the characteristics/behave of the shifts. Maybe an eleventh hour rethink was performed, the gearbox was sampled by SMG customers and they didn't like the smoothest of the original setup. Who knows.
Way too much of a conspiracy theory. First do you think BMW does not have enough testers and that they have not driven the hell out of SMG cars? Next all of the testers seemed to be quite familiar with SMG and they all loved the tranny. Footie, this just aint going to be Audi's DSG box.
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      03-27-2008, 07:50 PM   #174
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Nope, that is not it. Read my posts and proposal for a bet. I am betting on little to no downwrd spike on leading edge of the shift. This is totally independent as to whether or not you feel the jerk on shifts.
This sounds like the bets where I offer to pay someone elses event entry fee if they can drive faster than I do.

Don't sucker them too much swamp.
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      03-27-2008, 08:07 PM   #175
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Nope, that is not it. Read my posts and proposal for a bet. I am betting on little to no downwrd spike on leading edge of the shift. This is totally independent as to whether or not you feel the jerk on shifts.

When we first tried to agree to a bet, you backed away from your claims of near instantaneous shift times quickly.

I don't think we can come to terms.

Offer Footie "Double his IQ or no money back" see how much he wants to invest
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      03-27-2008, 08:17 PM   #176
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I don't think we can come to terms.
I would want to see a bet defined in the following terms.

Shift time = total time from when acceleration starts to drop during the gear change to when acceleration is back at or above the steady state for the next gear.

Put in terms of the real world graph:
Quote:
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This is real logged data from my 6mt car going 3->4 at laguna seca.



Log was from this driving session
http://video.google.com/videoplay?do...40764726878137
The time counted would be from just a hair before the 1.2s mark where acceleration starts to dip until 1.6s where acceleration has returned to the expected value for the next gear. So I would measure that at about 0.42s

You guys pick an over/under number for that metric.
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