[300hp]

Originally Posted by ShaneV78

I would be inclined to agree with you if the reason for the change to the HCC was just for the launch control but my original comment (Page 2) was that the best reason to change to the HCC was to allow the engine to be completely disengaged from the transmission for the sailing function!

Having a controllable clutch that allows for a proper launch function is a happy side-effect of that change!

Porsche also offers a sailing function like this on some models (I'm not referring to the hybrids) but then only with PDK because it allows them to open both clutches to fully disengage the engine.

I noticed that in the material you posted they make reference to this

Plug & Play: existing automatic transmission´s structure is utilizable

Pretty cool stuff, 2014 F30s FTW

[drob23]

Originally Posted by 300hp

I noticed that in the material you posted they make reference to this

Plug & Play: existing automatic transmission´s structure is utilizable

Pretty cool stuff, 2014 F30s FTW

Plug and play can mean a wide spectrum of things, in this case I'd assume they are talking from a manufacturing perspective, not a software/tuning. Usually with cars, they go through multiple levels of prototypes as they near production release. There's a lot of problems that arise when combining modules that you would not anticipate, because really no system lives inside a black box.

IMO replacing a major transmission component mid-cycle would only be undertaken if there was a serious flaw with the current one. It's not worth it if something doesn't play nice and they need to make a recall. There's a reason people advise others not to buy the first model year of a new generation.

[ShaneV78]

Originally Posted by drob23

I haven't researched it fully, but my understanding is that the current ZF 8 has a clutch of sorts that allows the fly wheel and transmission to mechanically engage and spin at the same speed. I know for certain the AH3 has a modified ZF 8 with something like this and is able to "sail". It might simply be some software on the front end that interacts with the TCM to display some "sailing info" through the MMI.

I think overall changes to the drivetrain of this magnitude are done only on the full refresh, and possibly the LCI, but it's hard to justify the added cost of R&D/chassis support/tuning procedure/manufacturing for something that "isn't broke". Maybe Honda is the exception with their incredibly crappy 2012 Civic refresh.

I put it some technical info in the AH3 thread about it, lemme see if I can find it.

Edit - http://www.aachen-colloquium.com/pdf...riebel_bmw.pdf Seems like the AH3 uses a device very similar to what you proposed, although the purpose is different - more to do with interaction of engine and motor.

I think you are referring to the lock-up clutch inside the torque converter... that is why the link between the engine and transmission feels solid once you are moving. The problem is that disengaging that clutch does not remove the drag on the transmission fully when you lift off the throttle, so the sailing wouldn't work... you would lose too much speed.

As for the AH3, it is an example of the modular nature of the transmission that I referred to previously. Essentially, they just replace the torque converter with the hybrid module which does indeed contain a clutch capable of disengaging the engine completely. A bonus is the hybrid module also replaces the alternator and starter motor, so it's a pretty elegant solution... but I digress!

http://www.zf.com/zfXmlServlet?resul...e=en#toggleBox

The whole strategy behind the 8HP from the outset was this modular system, allowing a manufacturer to configure a transmission package much like we might option up a vehicle...

My view on why they might go with the HCC is simply that there is no other practical way I can see for them to cleanly disengage and re-engage the motor. Someone else mentioned the idea of them just shifting it to neutral and then back in to gear when needed but I'm sure you would agree this is not good for the transmission in the long run. It probably wouldn't be the smoothest process either.

Finally, I think it just 'fits' the way BMW like to do things... by this I mean they like to have absolute control over every variable that can be managed. A fluid coupling doesn't really give that control, so I can see this being the future. Going back to the point about the lag, even if it is very minor, this would for example allow a scenario that when you tip in to the throttle, it first allows the engine to climb a few 100rpm before starting to engage, thus getting the turbo on boost even quicker. Not essential by any means but still an improvement that would not be possible with a torque converter...

[drob23]

Originally Posted by ShaneV78

The whole strategy behind the 8HP from the outset was this modular system, allowing a manufacturer to configure a transmission package much like we might option up a vehicle...

Yup, this makes sense and I think is one of the reasons everyone from Audi to BMW to Chrysler is using this box for RS7's to 328's to Jeep GC to Ram Trucks. But I think the modularity is not necessarily relevant within a model generation. It's hard to make a business case for "well we can order 300,000 units of your ZF8 slushboxes for 2 years but then switch over to 600,000 of your HCC clutches for the final 4 years after which time who knows what we're gonna do." The TCM is definitely tuned by BMW specifically on a car to car basis, so I imagine there would need to be at least 6-12 months of testing, validation and clinic work to make sure the ECM/TCM play nice and work properly with the new hardware which obviously will have different dynamics.

Originally Posted by ShaneV78

My view on why they might go with the HCC is simply that there is no other practical way I can see for them to cleanly disengage and re-engage the motor. Someone else mentioned the idea of them just shifting it to neutral and then back in to gear when needed but I'm sure you would agree this is not good for the transmission in the long run. It probably wouldn't be the smoothest process either.

I think the shifting to neutral seems more likely, but this is my opinion and I could definitely be wrong. I bet they could make it pretty smooth, considering how high the gear ratios are with 8 speeds.

Originally Posted by ShaneV78

Finally, I think it just 'fits' the way BMW like to do things... by this I mean they like to have absolute control over every variable that can be managed. A fluid coupling doesn't really give that control, so I can see this being the future. Going back to the point about the lag, even if it is very minor, this would for example allow a scenario that when you tip in to the throttle, it first allows the engine to climb a few 100rpm before starting to engage, thus getting the turbo on boost even quicker. Not essential by any means but still an improvement that would not be possible with a torque converter...

I agree that slush boxes are not the optimal solution when considering the physics, while DCT's are definitely more expensive and very hard to develop smooth control algorithms for. So I would not be surprised to see more advanced AT's like you've presented.

On a somewhat tangent - I'm curious why you think the HCC would improve turbo lag. I thought AT's were actually pretty good in this respect, since the engine is under load in all cases. Based on what someone said in the other thread about this (I think it was roundel), revving an engine with the clutch pedal engaged does not necessarily increase exhaust flow, since there is no load and thus no exhaust to generate turbo spoll. My understanding is that trying to launch cars with lots of turbo lag is not as easy as dumping the clutch at high RPM for the same reason. It seems like most anti-lag approaches involve changing ignition timing and using fancy recirculation devices. Or in the case of the N55, doing a very good job designing the twin-scroll inlet that provides good spoll over wide engine load operating conditions.

[300hp]

Originally Posted by ShaneV78

I think you are referring to the lock-up clutch inside the torque converter... that is why the link between the engine and transmission feels solid once you are moving. The problem is that disengaging that clutch does not remove the drag on the transmission fully when you lift off the throttle, so the sailing wouldn't work... you would lose too much speed.

As for the AH3, it is an example of the modular nature of the transmission that I referred to previously. Essentially, they just replace the torque converter with the hybrid module which does indeed contain a clutch capable of disengaging the engine completely. A bonus is the hybrid module also replaces the alternator and starter motor, so it's a pretty elegant solution... but I digress!

http://www.zf.com/zfXmlServlet?resul...e=en#toggleBox

The whole strategy behind the 8HP from the outset was this modular system, allowing a manufacturer to configure a transmission package much like we might option up a vehicle...

My view on why they might go with the HCC is simply that there is no other practical way I can see for them to cleanly disengage and re-engage the motor. Someone else mentioned the idea of them just shifting it to neutral and then back in to gear when needed but I'm sure you would agree this is not good for the transmission in the long run. It probably wouldn't be the smoothest process either.

Finally, I think it just 'fits' the way BMW like to do things... by this I mean they like to have absolute control over every variable that can be managed. A fluid coupling doesn't really give that control, so I can see this being the future. Going back to the point about the lag, even if it is very minor, this would for example allow a scenario that when you tip in to the throttle, it first allows the engine to climb a few 100rpm before starting to engage, thus getting the turbo on boost even quicker. Not essential by any means but still an improvement that would not be possible with a torque converter...

You are based in London, am planning a trip there this summer. 3 series are expensive to rent so may end up with a Peugot 207

[drob23]

Originally Posted by 300hp

You are based in London, am planning a trip there this summer. 3 series are expensive to rent so may end up with a Peugot 207

You're gonna rent a car in London?!?! Dude...I would highly advise against that Bus/train/tube/Ryan Air FTW

[alex2364]

Originally Posted by 300hp

You are based in London, am planning a trip there this summer. 3 series are expensive to rent so may end up with a Peugot 207

Where is it NOT expensive to rent a 3 Series??

[300hp]

Originally Posted by drob23

You're gonna rent a car in London?!?! Dude...I would highly advise against that Bus/train/tube/Ryan Air FTW

I will be driving from London to Dudley, so wont be in London for too long. If in London I would definitely use the tube, LOL

Originally Posted by alex2364

Where is it NOT expensive to rent a 3 Series??

I can handle $150/day not 300 pounds per day, lol.

[drob23]

Originally Posted by 300hp

I will be driving from London to Dudley, so wont be in London for too long. If in London I would definitely use the tube, LOL

I can handle $150/day not 300 pounds per day, lol.

Cool man, sounds like a great trip. $150/day is pretty damn steep but if the drive is nice or you need the flexibility then by all means. 300 pounds per day

[300hp]

The $150 is what BMW charges for a 328i weekend rental in the US I think. When I checked on a rental website in the UK I had seen 300 pounds a day for a 3 series. I Immediately knew the Peugot 207 had my name written al over it

I will take it in manual transmission though.

Off topic, but I guess we all needed to step away a bit

[drob23]

Originally Posted by 300hp

The $150 is what BMW charges for a 328i weekend rental in the US I think. When I checked on a rental website in the UK I had seen 300 pounds a day for a 3 series. I Immediately knew the Peugot 207 had my name written al over it

I will take it in manual transmission though.

Off topic, but I guess we all needed to step away a bit

I'm pretty sure you can rent F30's from avis, I would hope much cheaper than 150/day - I certainly wouldn't rent from BMW directly

Eh, it's an internet message board about cars...not like we're curing cancer or anything

I think OT posts are much better than making hundreds of threads about cheap interiors, 328 vs 335 or whatever magazine article has an F30 losing to something else.

[300hp]

Originally Posted by drob23

I'm pretty sure you can rent F30's from avis, I would hope much cheaper than 150/day - I certainly wouldn't rent from BMW directly

Eh, it's an internet message board about cars...not like we're curing cancer or anything

I think OT posts are much better than making hundreds of threads about cheap interiors, 328 vs 335 or whatever magazine article has an F30 losing to something else.

Depends on the market I guess, if you go to Vegas everything is priced better over there.

I haven't been in a manual transmission since my last trip overseas. The small cars tend to be the ones I am most comfortable with a manual transmission. Talk about being a chicken

[ShaneV78]

Originally Posted by drob23

Yup, this makes sense and I think is one of the reasons everyone from Audi to BMW to Chrysler is using this box for RS7's to 328's to Jeep GC to Ram Trucks. But I think the modularity is not necessarily relevant within a model generation. It's hard to make a business case for "well we can order 300,000 units of your ZF8 slushboxes for 2 years but then switch over to 600,000 of your HCC clutches for the final 4 years after which time who knows what we're gonna do." The TCM is definitely tuned by BMW specifically on a car to car basis, so I imagine there would need to be at least 6-12 months of testing, validation and clinic work to make sure the ECM/TCM play nice and work properly with the new hardware which obviously will have different dynamics.



I think the shifting to neutral seems more likely, but this is my opinion and I could definitely be wrong. I bet they could make it pretty smooth, considering how high the gear ratios are with 8 speeds.



I agree that slush boxes are not the optimal solution when considering the physics, while DCT's are definitely more expensive and very hard to develop smooth control algorithms for. So I would not be surprised to see more advanced AT's like you've presented.

On a somewhat tangent - I'm curious why you think the HCC would improve turbo lag. I thought AT's were actually pretty good in this respect, since the engine is under load in all cases. Based on what someone said in the other thread about this (I think it was roundel), revving an engine with the clutch pedal engaged does not necessarily increase exhaust flow, since there is no load and thus no exhaust to generate turbo spoll. My understanding is that trying to launch cars with lots of turbo lag is not as easy as dumping the clutch at high RPM for the same reason. It seems like most anti-lag approaches involve changing ignition timing and using fancy recirculation devices. Or in the case of the N55, doing a very good job designing the twin-scroll inlet that provides good spoll over wide engine load operating conditions.

Firstly, talking from (unhappy) experience, BMW have no issue making major changes within the life-cycle of a model. Just look at the e90 like mine, I got the N52 which had what I believe was a GM automatic. Sometime later the 330i was updated to the N53 (DI was added) with a ZF transmission. In addition there were two versions of the 335i... N54 & N55 both with ZF 6 Speed except on the coupe where they took the effort to swap in a DCT box with all the associated programming required... So a little bit of programming for the HCC is nothing. Just as an aside... the HCC module has existed since 2009, so they could have been working on this for some months already.

According to the ZF site, all the 8HP transmissions regardless of their configuration (So AH3 included) use exactly the same control module... they only need to change the control software to match the physical configuration. In terms of ordering, I can't imagine it being a huge issue... today they probably order say 10000 8HP's with a torque converter option, instead they will order 10000 8HP's with HCC option... just tick the other box as it were. Because of JIT manufacturing, this can be as simple as applying a new option code to the vehicle much like how the Pro Navigation option codes change when a major update is introduced.

My personal feeling is that BMW would not accept the notion of shifting in and out of drive while moving. It will cause extra wear and they would also not be able to control engagement as finely as with the HCC... I'm sure they could in theory make it smooth but it would be a fudge as opposed to a properly engineered solution.

The lag issue is an interesting one and there are two factors which should help the HCC reduce the lag. First though, a bit of theory...

Most people believe a turbo on spools up under load and in a conventional sense of watching the boost pressure build, this is probably accurate. Lag though is the time it takes the turbo to speed up, regardless of the actual boost/load at that time. In other words, lets say at idle the turbo is doing 20K rpm and at max boost it is doing 100K rpm. Lag would be the 0.5 seconds or so it takes to go from the one speed to the other but you can also be spinning the turbo at 100K rpm while producing relatively little boost when there is no load on the engine.

So boost is essentially the difference between the air being pumped by the turbo (which is usually pretty constant for a given turbo speed) and the amount of 'back-pressure' created by the engine by virtue of the increased load. The major difference though happens when you apply the load to the engine... with the turbo running at 20K, it will take a while to come on boost but with the turbo already at a 100K the boost would build almost instantly. The real issue of lag then is overcoming the inertia of the actual turbine itself as opposed to one of boost pressures.

So if you are able to delay the moment of engagement of the transmission by even just a few 10's of milliseconds, it will allows the turbo to speed up a bit more before the load is applied to the engine thus overcoming some of the lag.

The other added advantage is that the HCC is quite a bit lighter than a torque converter, so the engine spins up quicker and consequently also spins the turbo up that little bit quicker. Think of it as being like a lightened flywheel on manual cars... Bonus points for the fact that it would also make the shifts even quicker than they are now because the time taken for the revs to rise/fall to match the incoming gear would be reduced.

[rconti]

Originally Posted by bizzyqu

Maybe if more people bought the manuals and diesels they will, but they don't so too bad so sad

How many people are throwing money at BMW begging for a videogame gimmick launch control for their videogame transmissions?

Oh yeah, Lexus buyers that BMW is so desperately courting these days

It doesn't matter though, at the rate with which people are deciding they don't actually like driving their cars, we'll all be driving self-driving cars in a decade anyway.

[drob23]

Originally Posted by 300hp

Depends on the market I guess, if you go to Vegas everything is priced better over there.

I haven't been in a manual transmission since my last trip overseas. The small cars tend to be the ones I am most comfortable with a manual transmission. Talk about being a chicken

Haha...sounds like you should be renting a M135 6MT

[drob23]

Originally Posted by ShaneV78

Firstly, talking from (unhappy) experience, BMW have no issue making major changes within the life-cycle of a model. Just look at the e90 like mine, I got the N52 which had what I believe was a GM automatic. Sometime later the 330i was updated to the N53 (DI was added) with a ZF transmission. In addition there were two versions of the 335i... N54 & N55 both with ZF 6 Speed except on the coupe where they took the effort to swap in a DCT box with all the associated programming required... So a little bit of programming for the HCC is nothing. Just as an aside... the HCC module has existed since 2009, so they could have been working on this for some months already.

According to the ZF site, all the 8HP transmissions regardless of their configuration (So AH3 included) use exactly the same control module... they only need to change the control software to match the physical configuration. In terms of ordering, I can't imagine it being a huge issue... today they probably order say 10000 8HP's with a torque converter option, instead they will order 10000 8HP's with HCC option... just tick the other box as it were. Because of JIT manufacturing, this can be as simple as applying a new option code to the vehicle much like how the Pro Navigation option codes change when a major update is introduced.

My personal feeling is that BMW would not accept the notion of shifting in and out of drive while moving. It will cause extra wear and they would also not be able to control engagement as finely as with the HCC... I'm sure they could in theory make it smooth but it would be a fudge as opposed to a properly engineered solution.

The lag issue is an interesting one and there are two factors which should help the HCC reduce the lag. First though, a bit of theory...

Most people believe a turbo on spools up under load and in a conventional sense of watching the boost pressure build, this is probably accurate. Lag though is the time it takes the turbo to speed up, regardless of the actual boost/load at that time. In other words, lets say at idle the turbo is doing 20K rpm and at max boost it is doing 100K rpm. Lag would be the 0.5 seconds or so it takes to go from the one speed to the other but you can also be spinning the turbo at 100K rpm while producing relatively little boost when there is no load on the engine.

So boost is essentially the difference between the air being pumped by the turbo (which is usually pretty constant for a given turbo speed) and the amount of 'back-pressure' created by the engine by virtue of the increased load. The major difference though happens when you apply the load to the engine... with the turbo running at 20K, it will take a while to come on boost but with the turbo already at a 100K the boost would build almost instantly. The real issue of lag then is overcoming the inertia of the actual turbine itself as opposed to one of boost pressures.

So if you are able to delay the moment of engagement of the transmission by even just a few 10's of milliseconds, it will allows the turbo to speed up a bit more before the load is applied to the engine thus overcoming some of the lag.

The other added advantage is that the HCC is quite a bit lighter than a torque converter, so the engine spins up quicker and consequently also spins the turbo up that little bit quicker. Think of it as being like a lightened flywheel on manual cars... Bonus points for the fact that it would also make the shifts even quicker than they are now because the time taken for the revs to rise/fall to match the incoming gear would be reduced.

Thanks for the nice response. I am not too familiar with BMW practices regarding model refreshes (more familiar with domestic OEM's) so you could very well be right. I have a friend who curses his GM slushbox in his e46 330i.

Regarding turbo lag, I will again have to defer to you. I guess I assumed that revving the engine with no load on the flywheel would not generate enough exhaust to spoll the turbo up, but based on what you've said, this is probably wrong. Guess I'll have to read up more on it As a controls guy, we looked at some turbo diesel stuff one time for a class project, but the performance metrics pertained to emissions rather than performance. At the time I thought engine controls was pretty boring and simplistic (not the chemistry/physics, but the engineering models considered)

I would be curious how a ZF AT would feel with this clutch, since now, as far as I understand you, the engine would need to properly rev-match down shifts and more or less function like a DCT? How would this change creep control where a slushbox shines, are drivers going to feel more "jerky" type behavior when shifting 2-1 or moving from a stop?

[TheJoy]

Am I correct in presuming the announcements regarding EfficientDynamics, Launch Control, and ConnectedDrive affect the global market whereas the mention of the 118d, 318d, and 335d xDrive only concern the European market since these models haven't been specifically been unveiled in the U.S.?

[spatel19]

Are they going give any new interior or exterior color choices?

[itwasepic]

So I guess it's Business As Usual for us 6MT owners; glad I didn't hold out for 2014.

Now if BMW said they updated the iPhone connector to fit an iPhone 5, then I would be kicking myself!!!

Actually, I would have kicked myself if BMW offered saddle brown leather in the M-sport.

[seis-speed]

I see less 6MT's across the board, the 8 speed autos will be much easier to comply with EU/US fuel consumption requirements. Sucks.

[Falafel Combo]

Originally Posted by itwasepic

So I guess it's Business As Usual for us 6MT owners; glad I didn't hold out for 2014.

Now if BMW said they updated the iPhone connector to fit an iPhone 5, then I would be kicking myself!!!


Actually, I would have kicked myself if BMW offered saddle brown leather in the M-sport.

Otherwise, pretty lame changes. Which is fine. I'd rather them do that, then shoot all the '13 owners in the foot.


LCI better be good!

[ShaneV78]

Originally Posted by drob23

Thanks for the nice response. I am not too familiar with BMW practices regarding model refreshes (more familiar with domestic OEM's) so you could very well be right. I have a friend who curses his GM slushbox in his e46 330i.

Regarding turbo lag, I will again have to defer to you. I guess I assumed that revving the engine with no load on the flywheel would not generate enough exhaust to spoll the turbo up, but based on what you've said, this is probably wrong. Guess I'll have to read up more on it As a controls guy, we looked at some turbo diesel stuff one time for a class project, but the performance metrics pertained to emissions rather than performance. At the time I thought engine controls was pretty boring and simplistic (not the chemistry/physics, but the engineering models considered)

I would be curious how a ZF AT would feel with this clutch, since now, as far as I understand you, the engine would need to properly rev-match down shifts and more or less function like a DCT? How would this change creep control where a slushbox shines, are drivers going to feel more "jerky" type behavior when shifting 2-1 or moving from a stop?

No problem... I like to ponder these things instead of actually doing real work!

Obviously there is a bit more to the rpm/boost relationship than I covered in the last post but on a basic level, discounting outside factors, an engine spinning at 5000rpm creates 5 times more exhaust flow than it does at 1000rpm. So clearly the turbo attached to it would also spin at about 5 times the speed but only until it meets some resistance... like a load on the engine.

Let's assume for a moment that while running without a load at 5000rpm, the boost indicated is 0 (actually 14.7psi/atmospheric) because the turbo is only moving as much air as the engine needs to maintain that speed. If you halved the speed to 2500rpm, the pressure in the intake manifold would double unless the turbo slowed back down to match the demand. But the alternative way of looking at it is you now have a boost level of 14.7psi + atmospheric 14.7psi = 29.4psi total. Unless you vent that pressure to the outside via a BOV, you would need to double the fuel injected to prevent the mixture getting too lean. So now you are creating the same size explosion at 2500rpm as what you would have had at 5000rpm and consequently you have the same amount of exhaust gas to keep the turbo spinning.

The reason you can build more boost under load then is because you are limited by your rev limiter (and mechanical sympathy) as to how much exhaust flow you can generate without a load. Once you apply a load to the engine, you can then manipulate the wastegate instead to determine exactly how much boost you generate.

Now the way that most manufacturers try to mitigate against lag is by using smaller turbos and limiting total boost with the wastegate. This combination means that you can get the turbos up to speed much more easily even without a load on the engine. But now it gets interesting... imagine a scenario where you use the ECU to close the wastegate completely while also delaying the engagement of the clutch for a few milliseconds when it senses the first few mm of travel on the throttle and you have a situation where lag can be almost entirely anticipated and eliminated.

With regards to how it would feel, that is entirely up to BMW. The point is they can program it to creep or instead combine it with the auto hold function so that you don't move until you press the throttle. To give two examples, in the CLS it behaves much like a normal automatic. I found a video on YouTube that illustrates the point nicely. At 0:30 you see an example of a normal start and there is not much between it and a typical automatic. At 3:15 on the other hand you see a slightly more aggressive start (but not L/C) and if you watch closely, you will notice the revs jump up quite a bit before the clutch engages.

The latter, although a more extreme example, does illustrate the type of strategy that could be used to reduce lag by allowing the engine to say jump from a 500rpm idle to 8-900rpm before starting to engage. It is also worth noting that although MB use their own 7 speed auto box, they are actually using the ZF HCC as the starting element!

https://www.youtube.com/watch?v=VC-QGzTcrTI

I have also seen it reported that a MP4-12C creeps like an automatic and this is on a DCT box, so clearly it's all down to how the OEM configures it to behave.

Finally, on the matter of the rev matching, it's not actually the HCC engagement speeds that matter as my understanding is that once moving it stays locked and the transfer from one gear to another is effected by the clutches inside the box. This is already the case today because once you are moving the clutch inside the torque converter locks up and stays that way until you stop again. In that sense the 8HP behaves a little like a DCT except that instead of 2 clutches, it has about 4 or 5 and uses different combinations to create the various ratios.

Where the HCC does make a difference is in the inertia/momentum that needs to be overcome to match the engine speed to that of the incoming gear and it is the lower mass and smaller diameter that make all the difference. The standard torque converter is around 20kg and 30cm across where the HCC is 14kg and a little over 20cm across. So this reduces the torque moment of the coupling and is probably about the same as losing about 2/3rds of the weight of your flywheel in a manual car. If you think of how quickly an F1 engine revs, a lot of that is down to the tiny 10cm clutch pack and the lack of flywheel effect (plus of course the lightweight internals) and it is a similar effect here that allows for quicker rev-matching to the incoming gear.