DCT vs Conventional Automatic

[Tom K.]

Originally Posted by maxnix

I always liked his remark in a test of the 1957 Pontiac that is was "as smooth as a prom queen's thighs." Quite racy for those days. I imagine few here remember the Eisenhower years.

He was probably right. While I avoided prom queens on general principles, my driving lessons were taken in a '57 Chieftain and it was a delight to drive. The instructor provided an AT equipped '52 Pontiac for my driver's test as the '57 was a 3 speed MT - significantly faster than the 4 speed Hydramatic, but tougher for a novice driver to master.

Tom

[vantagesc]

Originally Posted by BrokenVert

Maybe the GM unit in the 128 is sub-par but the ZF box is absolutely one of the best slushies ever made. Its responsive and it shifts more than quickly enough to not lose boost (this is the reason that nearly all of the sub 11 second 135s are autos)

And yes the HP-6 rev matches on down shifts. I can you people a video but I really dont think its necessary.

Is there a video of the new 135i auto downshifting somewhere on the net? Looks like I was driving one of the older autoboxes. I'd like to see how close the downshifting is, because I thought that was the advantage of DCT.

[Diver]

I remember reading somewhere that the automatic in the 135i was not as good as the one in the 335i. Was that wrong, or were they comparing 128i and 328i transmissions. I had a GM five speed automatic in a 2000 MY 325. Today it would be sub par, but 11 years ago it was pretty good compared to whatever else was available.

Shift speeds aside, DCT 135i's run 0-60 quicker than a manual, not to mention a manual might not be shifted perfectly every time. Usually, a manual accelerates more quickly than an automatic, although the difference is becoming smaller with the newer transmissions. Every now and then I do hear about automatic equipped cars doing better the drag strip than manual. This was reported for the 2011 Mustang GT. That automatic does not have a driver shift mode. It is really designed to go in a F150.

[BSM 335I]

Originally Posted by BrokenVert

Wow you DCT guys are really uninformed.

I dont remember where it is but somebody posted a shift time comparison chart between the ZF HP-5 HP-6 and the DCT when DCT first came out.

The ZF HP-6 thats in all auto 135s made between 08 and 10 are only off DCT shift times by .05 or something obnoxiously close like that on all up shifts and down shifts except for the 2-1 down shift (why would you be making that anyway?)

Maybe the GM unit in the 128 is sub-par but the ZF box is absolutely one of the best slushies ever made. Its responsive and it shifts more than quickly enough to not lose boost (this is the reason that nearly all of the sub 11 second 135s are autos)

And yes the HP-6 rev matches on down shifts. I can you people a video but I really dont think its necessary.

And to address the mileage concern, on the 300 mile drive between Syracuse and my home I routinely get 31-32 MPG actual. What do you DCT guys get?

This can be attributed to the fact that the HP-6 has a lockup Converter that reduces drive train losses at steady cruise and under WOT

Took you long enough!

Originally Posted by maxnix

No, the TC will only lock at lower power requirements like at steady cruise. It will not lock up at WOT.

TC locks up 100% past 50mph and about 80% when under that in sports mode.

The new TC on the ZF6HP21 was massively improved over the rest. Not to mention the TC decouples itself from the engine at standstill with NIC (Neutral Idle Control). huh?

[RPM90]

Originally Posted by maxnix

0-60 mph is a relic from the reviews of Tom McCahill in Mechanix Illustrated, the sine qua non of automobile reviewers at the time.

He also judged trunk capacity with his setter in the trunk.

I always liked his remark in a test of the 1957 Pontiac that is was "as smooth as a prom queen's thighs." Quite racy for those days. I imagine few here remember the Eisenhower years.

True, it's an age old test spec that doesn't give the whole story.
But, it's just one factor in a number of basic factors by which to compare cars. One has to take many factors into account to form somewhat of an "informed" opinion.
The spec is not at fault, it's the people who think that only 0-60 is the most relevant spec.

It does sell cars to certain buyers, that's why auto makers give it credence. For most daily drivers who think a stop light is a drag race light that spec brings them to buy certain cars.

[kgaler]

I've always thought that 0-60 is a practical spec. It gives a good idea of what the car is capable of for things like getting up to speed on the highway, for instance. Much more useful than 1/4 mile times.

Of course, if I had my way the US would go all metric. WFT? But, that is a different issue.

[Diver]

If there is a drawback with 0-60 it is that some really fast cars are traction limited. C&D came up with their 5-60 test to try and eliminate the traction issue. I think something like 10-120 might be a good way to test as it eliminates both traction and low end performance issues while giving a better separation of the cars with good power to weight ratios and some aerodynamics thrown in. The Corvette tuner Lingenfelter once said his customers were mainly interested in getting to 120 quickly. People paid what was big bucks back then to get 500 HP cars that are nowhere near that expensive now in inflation adjusted terms.

[Aries932]

Originally Posted by Diver

If there is a drawback with 0-60 it is that some really fast cars are traction limited. C&D came up with their 5-60 test to try and eliminate the traction issue. I think something like 10-120 might be a good way to test as it eliminates both traction and low end performance issues while giving a better separation of the cars with good power to weight ratios and some aerodynamics thrown in. The Corvette tuner Lingenfelter once said his customers were mainly interested in getting to 120 quickly. People paid what was big bucks back then to get 500 HP cars that are nowhere near that expensive now in inflation adjusted terms.

Simply put 0-60 comes with a group of problems...
1) Traction...for example if you put wider and better tires on the 135i it would significantly drop our 0-60 time.
2) Driver error...This is much more apparent on a manual car, the better you can launch the better your 0-60 time.
3) Automatics...well we all know they are not going to brake stand an automatic...so automatics really get the shaft in 0-60 times
4) Gearing...the Corvette Z06 for example goes past 60 in 1st gear.


I am sure if you give me another couple hours I can come up with another 4-5 reasons, but these are just the ones I can think of off the top of my head.

[PMMM]

All this griping over which transmission is what. All that really matters is being able to hit 150 on a stretch of highway (near my home...don't tell the police) that is about 1.5 miles long, perfectly smooth, and with a good wide visual of the shoulders (to see if any police are running radar).

And I've had the pleasure of driving a 128i with an automatic...did not like it. Far slower and much more sluggish than my 135i DCT. Still zippier than any Corolla or Civic on the road, but not as quick as the 135i DCT. Sorry. Real world tests tell all, not modified closed-course trials. Sitting at a light next to a dude in a 128i vert with my 135i vert not too long ago...a friendly race to the next light...he with an auto, me with a DCT. Me sitting at the next light waiting a second or two for him. Again...real world test. The OP asked which transmission was "better". Instead of giving real world tests, people here wanted to get into pissing contests over modified this and chipped that and brake-standing and torque launching.

I think we're all here for the same reason...we like BMW and we especially like the 1's...can't we all get along?

[BrokenVert]

^you can't compare an auto 128 to a DCT 135 or even an auto 135. Two entirely different leagues.

an auto 135 vs a DCT 135 will be a very close race as both transmissions are fantastic...that's all I'm trying to say

[Aries932]

Originally Posted by PMMM

All this griping over which transmission is what. All that really matters is being able to hit 150 on a stretch of highway (near my home...don't tell the police) that is about 1.5 miles long, perfectly smooth, and with a good wide visual of the shoulders (to see if any police are running radar).

And I've had the pleasure of driving a 128i with an automatic...did not like it. Far slower and much more sluggish than my 135i DCT. Still zippier than any Corolla or Civic on the road, but not as quick as the 135i DCT. Sorry. Real world tests tell all, not modified closed-course trials. Sitting at a light next to a dude in a 128i vert with my 135i vert not too long ago...a friendly race to the next light...he with an auto, me with a DCT. Me sitting at the next light waiting a second or two for him. Again...real world test. The OP asked which transmission was "better". Instead of giving real world tests, people here wanted to get into pissing contests over modified this and chipped that and brake-standing and torque launching.

I think we're all here for the same reason...we like BMW and we especially like the 1's...can't we all get along?

Wait so let me get this straight you just compared a automatic transmission from the 128i to the 135i DCT....for your information the 135i has a much better automatic transmission than the 128i.

Next you think because you beat that 128i that runs about 70hp lower than you that makes your transmission better...believe me it is completely due to the fact that he has a 2.8L naturally aspirated engine putting out 230hp instead of a 3.0L turbo'ed engine putting out 300hp.

Your entire post is so ridiculous. What real world tests...let me go race an automatic honda civic and because I beat him that means that DCT is better than an automatic...really...

Lastly where the hell do you think we read all of our statistics from...umm I dont know maybe professional drivers that conducted "real world tests", or other 1addicts members that conducted "real world tests".

Please refrain from trying to insult members because we are having a discussion and call it a pissing contest.

[BrokenVert]

Originally Posted by Aries932

.believe me it is completely due to the fact that he has a 2.8L naturally aspirated engine putting out 230hp instead of a 3.0L turbo'ed engine putting out 300hp.

I was with you until I read this...please check your facts before you post

[Aries932]

Originally Posted by BrokenVert

I was with you until I read this...please check your facts before you post

yea yea yea 3.0L naturally aspirated...keep forgetting that those numbers do not mean anything anymore...somewhat annoying...anyways regardless it is still 230hp which was the heart of the arguement.

[BrokenVert]

Originally Posted by Aries932

yea yea yea 3.0L naturally aspirated...keep forgetting that those numbers do not mean anything anymore...somewhat annoying...anyways regardless it is still 230hp which was the heart of the arguement.

Just sayin that displacement affects the torque curve. And ask any drag racer torque gets you down the track faster than horsepower

[1-2MANY]

Originally Posted by Aries932

Wait so let me get this straight you just compared a automatic transmission from the 128i to the 135i DCT....for your information the 135i has a much better automatic transmission than the 128i.

Next you think because you beat that 128i that runs about 70hp lower than you that makes your transmission better...believe me it is completely due to the fact that he has a 2.8L naturally aspirated engine putting out 230hp instead of a 3.0L turbo'ed engine putting out 300hp.

Your entire post is so ridiculous. What real world tests...let me go race an automatic honda civic and because I beat him that means that DCT is better than an automatic...really...

Lastly where the hell do you think we read all of our statistics from...umm I dont know maybe professional drivers that conducted "real world tests", or other 1addicts members that conducted "real world tests".

Please refrain from trying to insult members because we are having a discussion and call it a pissing contest.

Yah, the Gm unit in the 128i is different compared to the ZF in the 135i's. Had a 128i loaner with the auto and it was seriously boring to drive. Even my friend's v6 camry felt a lot quicker.

[Aries932]

Originally Posted by BrokenVert

Just sayin that displacement affects the torque curve. And ask any drag racer torque gets you down the track faster than horsepower

...ok you do realize the 128i comes with only 200tq...while the 135i has 300tq.

I understand what displacement effects...I paid more attention to the power numbers than the displacement.

There are 6.3L mercedes AMG engines putting out engines putting out 518hp and 465tq...while the 6.2L V8 from pontiac puts out only 415hp and 415tq.

If you have enough technology you can pull immense amounts of power out of a small engine. I mean just look at F1 racing a 2.4L V8 naturally aspirated that is restricted to only putting out 750hp and 18,000rpms...lol they are easily capable of 900-1000 hp.

[///S55]

stop arguing
somehow get a video comparison of a stock N54 steptronic vs N55 DCT.

[Aries932]

Originally Posted by nolim1t

stop arguing
somehow get a video comparison of a stock N54 steptronic vs N55 DCT.

What would a video do...that wouldnt really help...anyways here is a summary of what has been said. Below are my original reasons why to get DCT over an automatic.

Reasons to get DCT over an Automatic

1) Faster Shifting (actually so fast that you do not loose boost in between shifts)

Apparently the shifting is not really that much faster according to BrokenVert who said:

"I dont remember where it is but somebody posted a shift time comparison chart between the ZF HP-5 HP-6 and the DCT when DCT first came out.
The ZF HP-6 thats in all auto 135s made between 08 and 10 are only off DCT shift times by .05 or something obnoxiously close like that on all up shifts and down shifts except for the 2-1 down shift (why would you be making that anyway?)"

2) Less power transfer loss. Automatics are usually around 20%-22% power loss, while DCT and manuals usually stick around 15%.

This still has not been proven to be incorrect. I am pretty sure that this is true.

3) More fuel efficient. Manuals in general are more fuel efficient than BMW's 6 speed automatics. Although I must say BMW's new 8-speed ZF auto is more fuel efficient than the DCT. Most automatics lose their power and fuel efficiency in the torque converter.

This was proven wrong due to the torque converter locking mechanism...so basically it is not more fuel efficient if you do city driving...but anything over 50 mph it will be due to the DCT being a wet clutch. This was originally pointed out by driver who said:

"The DCT BMW uses has a wet clutch which has pumping losses.Even the old 6 speed steptronic in a 335i gets better gas mileage than the lighter 135i with DCT. The ZF 8 speed is better still. Dry clutch DCT's such as are used in the VW GTI are as efficient as manual transmissions. However, dry clutch DCT's are limited in the amount of torque they can handle."He was incorrect about the 335i thing but correct about the rest.

4) Faster shifting response. Automatics although they are much faster than they were a couple years ago still lag a bit when you tap the paddle. DCT is extremely responsive.

Really this is just how long it takes the electronics to tell the car to shift...Sounds like the new automatics from what some people said are much better.

5) Launch Control (although brake torquing 2nd gear pulls seem to be faster with automatics)

Can't really argue here...brake torquing does put much more strain on the car than launch control since that just burns the clutch.

6) Throttle blip downshift. The DCT automatically rev matches when downshifting which sounds pretty incredible once you get a exhaust on the car. The automatic does not really have a need to do the whole throttle blip due to the way an automatic transmission works.

This is according to BrokenVert again who said:

"And yes the HP-6 rev matches on down shifts. I can you people a video but I really dont think its necessary."

Which I think we have different definitions of rev match but whatever...

So DCT advantages after all this discussion leave us with better power loss 15% over 20-22%...and launch control...I would say power loss being the most important...unless someone wants to refute that also.

[BSM 335I]

Originally Posted by BrokenVert

^you can't compare an auto 128 to a DCT 135 or even an auto 135. Two entirely different leagues.

an auto 135 vs a DCT 135 will be a very close race as both transmissions are fantastic...that's all I'm trying to say

+1. GM vs ZF

[RPM90]

Originally Posted by Aries932

Wait so let me get this straight you just compared a automatic transmission from the 128i to the 135i DCT....for your information the 135i has a much better automatic transmission than the 128i.

Next you think because you beat that 128i that runs about 70hp lower than you that makes your transmission better...believe me it is completely due to the fact that he has a 2.8L naturally aspirated engine putting out 230hp instead of a 3.0L turbo'ed engine putting out 300hp.

Your entire post is so ridiculous. What real world tests...let me go race an automatic honda civic and because I beat him that means that DCT is better than an automatic...really...

Lastly where the hell do you think we read all of our statistics from...umm I dont know maybe professional drivers that conducted "real world tests", or other 1addicts members that conducted "real world tests".

Please refrain from trying to insult members because we are having a discussion and call it a pissing contest.

Wow. Every time you post you are just full of attitude and insult when its not even called for. I think, no, I know it is you that is having a pissing contest while others are trying to have a discussion.
You just had to try and insult only to show that you don't even know what engine is in the 128i. That equals FAIL!
You claim to know facts that others don't, and you don't even know what engine is in the 128i. Too funny!

[RPM90]

Originally Posted by Aries932

...ok you do realize the 128i comes with only 200tq...while the 135i has 300tq.

I understand what displacement effects...I paid more attention to the power numbers than the displacement.

Even after being owned by your lack of facts, you still have the nerve to write, "...ok you do realize....."?

I know brokenvert is quite aware of what you think you are schooling him on.

[Aries932]

I am not going to quote you because honestly I am over sitting and having these off topic attacks toward each other....i respect your opinion...but i completely disagree with you...plain and simple.

I would rather not argue anymore with anyone in this thread hence why I posted and entire post about the points of my arguement where the things that I thought were benefits of DCT actually were not.

Coming in after I made an entire post laying out where I was incorrect seems a bit...weird honestly.

Do you think that naming brokenvert as proving me wrong two times shows that I am trying to "school him"?

I just do not see how that is me being rude. Anyways please lets just drop it and stay on topic and just not talk to each other anymore in this thread.