What-will-they-think-of-next dept.: VW developing 10-speed (!) DSG, high-output TDI

[VeeDubTDI]

And the Ford 5R110W is a 6-speed that switches patterns from 1-2-3-5-6 (normally) to 1-2-3-4-6 below 5 degrees F. (4th is 1.09:1, 5th is 1.00:1.)

However, the DSG has the issue that shifting between odd and even gears is fast, because it preselects the gear in the other box based on what it thinks you'll want, then switches clutches when you (or it) wants the shift. Skip-shifting between odd gears alone, or between even gears alone, is not fast, though, because then it's forced to act like a single-clutch gearbox - disengage clutch, shift, re-engage clutch.

So, a 1-4 shift on a DSG can be as fast as a 1-2 (well, plus the time for the clutch slip to resolve itself), whereas a 1-3 cannot be, for instance.

Also, fast shifts on a DSG allow for some engine torque to be maintained to the wheels during the shift. Basically, in a DSG, skip-shifting is rarely the right answer, it's better to fast shift through every gear.

Interestingly, when the DSG wants to go from 6th to 4th (highway downshift in cruise control), it goes 6-5-4 very quickly. 5th is essentially skipped over even though the display flashes it briefly as it goes through it.

As for GPS predictive cruise control, Fifth Gear had a segment on that recently in a Bentley.

 

[NoSmoke]

My 1980s Yanmar has shuttle shift. It has three manual gears and three shuttle shift gears- total of nine gear ranges. It's not dsg. In fact I don't even know how it works. But it's very durable and nice to use.

Hey, I test drove one of those way back when - nice machine! I still have the 1980 Yanmar 2 banger and it still runs like new. Yanmar made some damn nice stuff...

 

[German_1er_diesel]

I agree. The most current Mercedes twin turbo 2.1 doesn't even break 200hp. BMW twin turbo 2.0 is less than 180hp.

180hp-ish is the single turbo. The twin turbo BMW I4 is 218hp (125d, 325d, 425d, 525d, X1 25d, X3 25d, X5 25d...)

 

[LRTDI]

Ten?????

Have we moved on from HP wars to gearbox wars?

 

[VeeDubTDI]

Ten?????

Have we moved on from HP wars to gearbox wars?

Hopefully. Do more with less and be more efficient.

 

[bhtooefr]

It sounds like both, really.

I mean, this would be the most powerful diesel Passat ever, by quite a lot - 170 hp 2.0 PD/CRs in the B6 and B7, and a 180 hp VP44-pumped 2.5 V6 in the B5.

 

[Debra Morgan]

It sounds like both, really.

I mean, this would be the most powerful diesel Passat ever, by quite a lot - 170 hp 2.0 PD/CRs in the B6 and B7, and a 180 hp VP44-pumped 2.5 V6 in the B5.

Power is right up my alley....this would be sweet!

 

[kevin_in_idaho]

10 speed or CVT

I personally think they are doing a 10 speed because they can't figure out how to do a CVT w/ the diesel torque. They are doing 10 speeds as a response to CVT and trying to make it as close as they can without doing a real CVT.

 

[bhtooefr]

There's other problems with the CVT, though, than just torque handling.

A huge problem is power loss. Basically, CVTs only beat conventional torque converter automatics for efficiency due to the ratio flexibility - otherwise, they're the least efficient design out there. If you can approach CVT ratio flexibility with a torque converter automatic, you're beating a CVT, and if you can approach CVT ratio flexibility with a double-clutch gearbox, you're blowing the CVT away.

 

[darrelld]

Subaru has a CVT that can handle diesel torque, its available in the 2015 3.6L Outback and 2014 Forrester XT. The CVT equipped 3.6 Outback only beats my 5 speed auto Outback by 10%. Not much of a gain, they could probably get the same efficiency by going to DI and get a horsepower bump.

 

[RNDDUDE]

More gears allows the engine to operate in a narrower RPM range, and thus the engine can be more optimized to run more efficiently within that narrower rpm range.....higher max power, better fuel efficiency, lower emissions.

 

[German_1er_diesel]

I personally think they are doing a 10 speed because they can't figure out how to do a CVT w/ the diesel torque. They are doing 10 speeds as a response to CVT and trying to make it as close as they can without doing a real CVT.

Considering you CAN buy an Audi A4/A5/A6 or A7 with a V6 TDI, front wheel drive and a CVT in Europe, we can rule that out.

http://www.audi.de/de/brand/de/neuw.../diesel.engine_compare.4ga0nh_1.standard.html

 

[squeegee_boy]

Local market preference seems to be a big driver
http://blog.caranddriver.com/the-co...-officially-acknowledges-decades-of-missteps/
Dreisbeck also highlighted market-related preferences on the transmission side: In Japan, customers accept the “overshooting” engine speed of a CVT transmission; power, not speed, increases with engine speed, and the torque requirements are moderate. Europeans, on the other hand, demand a linear relation between engine and vehicle speed. The torque requirements are high. Naturally aspirated gasoline engines with CVT transmissions and softly calibrated torque-converter automatics are the right concept for Japan, but in Europe, customers require turbocharged gasoline or diesel engines with manual transmissions, dual-clutch automatics, or “stiffly” calibrated torque-converter automatics. These vastly different preferences highlight the limits of global standardization.

 

[compu_85]

Interestingly, when the DSG wants to go from 6th to 4th (highway downshift in cruise control), it goes 6-5-4 very quickly. 5th is essentially skipped over even though the display flashes it briefly as it goes through it.
.

I was going to ask you about this. The few times I've been driving when the Passat did the 6-4 shift I didn't recall seeing it go "through" 5th. It seemed like it went directly from 6th to 4th, and it happens very quickly. It might be possible it has 5th selected on the odd clutch but doesn't actually engage it.

-J

 

[German_1er_diesel]

Not in the American market.

In the American market, the 328d is the only 3-series diesel, and that's pretty much the same as the Euro 320d (+urea).
Single VTG turbo.
All current American-market BMW diesels are single turbo.

 

[VeeDubTDI]

I was going to ask you about this. The few times I've been driving when the Passat did the 6-4 shift I didn't recall seeing it go "through" 5th. It seemed like it went directly from 6th to 4th, and it happens very quickly. It might be possible it has 5th selected on the odd clutch but doesn't actually engage it.
-J

I think it hits 5th just long enough to shed 6th gear from the even clutch and jump to 4th.

 

[03_01_TDI]

In the American market, the 328d is the only 3-series diesel, and that's pretty much the same as the Euro 320d (+urea).
Single VTG turbo.
All current American-market BMW diesels are single turbo.

It's called "twin power" but its a single turbo with twin scrolls... Thanks for the correction.

 

[bhtooefr]

Apparently "twin power" now means it has a turbo, and nothing about what that turbo is.

(It's single-scroll on the diesel.)

 

[German_1er_diesel]

Yes, only the gassers have twin scroll turbos. BMW diesels don't.

 

[earlthepearl]

OK, I get it. Six speeds or ten speeds, the objective is to maintain lower engine speeds which results in higher fuel economy. My question concerns dpf regens. It seems that they are programed to occur at around 2000 rpm or more. That isn't a problem with the current set up of a 6 speed manual, or DSG, at highway speeds of 65-70 mph.

If I'm cruising along at 80 mph in my 10 speed DSG, and my engine is turning, say 1000-1200 rpm, how will the regen occur? No problem on the Autobahn. Just crank it up to 200 kmph. I guess those German engineers will figure out a way to trigger regens at lower engine speeds. Otherwise, I'll need to drop my 10 speed down to 5th gear on occasion until I feel that regen stumble.

I'm no genius. Just sitting here with nothing to do but read these posts, and this weird thought came out of nowhere.

 

[IndigoBlueWagon]

Not sure where the "regens above 2K" came from, but I think it's an urban myth. 2000 RPM in my Golf is 74 MPH. Not easy to maintain that most days on the limited access highways around here. If I lived in LA I'd never see that speed in most commutes. I have to think this isn't true.

 

[bhtooefr]

And even if they did need to do that, the transmission would be commanded to give a certain RPM level, and would automatically downshift.

And, the 10-speed likely won't be used to give a 1000-1200 RPM freeway cruise, it'll be used to make the gaps between gears even closer (speeding up shifts and reducing wear, and giving more choices for the optimal ratio at a given vehicle speed), and make the bottom gears shorter (improving performance from a standstill, the weak point of the DSG).

 

[darrelld]

OK, I get it. Six speeds or ten speeds, the objective is to maintain lower engine speeds which results in higher fuel economy. My question concerns dpf regens. It seems that they are programed to occur at around 2000 rpm or more. That isn't a problem with the current set up of a 6 speed manual, or DSG, at highway speeds of 65-70 mph.

If I'm cruising along at 80 mph in my 10 speed DSG, and my engine is turning, say 1000-1200 rpm, how will the regen occur? No problem on the Autobahn. Just crank it up to 200 kmph. I guess those German engineers will figure out a way to trigger regens at lower engine speeds. Otherwise, I'll need to drop my 10 speed down to 5th gear on occasion until I feel that regen stumble.

I'm no genius. Just sitting here with nothing to do but read these posts, and this weird thought came out of nowhere.

DPF regens are generally triggered by a drop in the amount of differential pressure drop across measured points on the DPF. Once the system determines a regen is required to improve the differential pressure ratio it adds additional fuel in the case of an active regen to bring the DPF up to regen temps.

I have seen regens start shortly after a cold start and low idling through my neighborhood. In order to properly regen a certain amount of air flow must be maintained so you will notice a slight increase in boost pressure and rpms.

I believe a regen will also trigger based upon a certain number of miles that have passed since the last regen.