MANUAL FTW?

[Nawaaz]

Originally Posted by dcstep

You're in for a treat.

Now that I've been to the track and got that out of my system, I only hit the redline on the street on entrance ramps. It IS nice to blast up to 75 mph or so in a flash. Of course, at the autocross course I hit the redline pretty routinely. The car seems to love it.

Dave

Looks like I need to give the track a visit pretty soon.....And often.

Otherwise I'll be getting tickets every other day!

[zenderm3]

Hearing all this conversation makes me want my car sooner...

[SenorFunkyPants]

Originally Posted by southlight

I really doubt that. M DCT is a hydraulic double clutch transmission with wet clutches. You'd need a dry clutch setup with electromechanic actuation to come near to an MT in terms of drivetrain losses.
Best regards,
south

Hmmm what better indicator of drivetrain losses is there than the fuel consumption and C02 emissions of two identical cars, one with a DCT and one with a MT running an identical fuel consumption cycle?
A 5% improvement is a significant difference and to be able to achieve that in a DCT car with a drive efficiency penalty through quicker shifts alone, sounds unlikely.
However as always I could be wrong, but for the moment I remain unconvinced.

[cj350]

track sounds fun

[Nawaaz]

Originally Posted by zenderm3

Hearing all this conversation makes me want my car sooner...

It's ok zenderm3........Just watch those porn vids we were all talking about in the other thread.

There, that should pass the time. hahahehe

[endofanera7]

Bee a mann, doo thee right thinggg!

[southlight]

Originally Posted by SenorFunkyPants

Hmmm what better indicator of drivetrain losses is there than the fuel consumption and C02 emissions of two identical cars, one with a DCT and one with a MT running an identical fuel consumption cycle?
A 5% improvement is a significant difference and to be able to achieve that in a DCT car with a drive efficiency penalty through quicker shifts alone, sounds unlikely.
However as always I could be wrong, but for the moment I remain unconvinced.

I'm too lazy to work through the relevant EU directive right now. I'll have a look at it later. If I remember correctly some parts of that cycle are driven in the top gear, so the advantage of the 7th gear alone might be good for some improvement.


Best regards,
south

[SoreHead]

Originally Posted by SenorFunkyPants

Hmmm what better indicator of drivetrain losses is there than the fuel consumption and C02 emissions of two identical cars, one with a DCT and one with a MT running an identical fuel consumption cycle?
A 5% improvement is a significant difference and to be able to achieve that in a DCT car with a drive efficiency penalty through quicker shifts alone, sounds unlikely.
However as always I could be wrong, but for the moment I remain unconvinced.

Different gearing will always give difference consumption.

[JCtx]

Originally Posted by southlight

M DCT is a hydraulic double clutch transmission with wet clutches. You'd need a dry clutch setup with electromechanic actuation to come near to an MT in terms of drivetrain losses.

It's practically the same thing in terms of losses, and both kinds need electromechanical clutch actuation for automated control. Contrary to popular belief, a wet clutch is not 'churning' in oil, even with the engine off. It just means the clutch comes IN CONTACT with oil (some spray oil on the clutch pack and some don't). The main reason for a wet clutch is PACKAGING (which is needed with a 2nd clutch in there), but am sure weight/cost savings (vs dry clutches) were an important consideration as well. And the reason for better 'efficiency' is the 7th gear.

[southlight]

Originally Posted by elp_jc

It's practically the same thing in terms of losses, and both kinds need electromechanical clutch actuation for automated control. Contrary to popular belief, a wet clutch is not 'churning' in oil, even with the engine off. It just means the clutch comes IN CONTACT with oil (some spray oil on the clutch pack and some don't). The main reason for a wet clutch is PACKAGING (which is needed with a 2nd clutch in there), but am sure weight/cost savings were an important consideration as well. And the reason for better 'efficiency' is the 7th gear.

I didn't say they're 'churning' in oil. My understanding is that wet clutches are necessary for heat dissipation, so they're not the reason for higher losses per se but a solution to keep the clutches within the operational range. Regarding actuation, I checked the Getrag website and they're stating the clutch operation is hydraulic. So far I only know of one double clutch transmission which has an electromechanical operation (DSG).


Best regards,
south

[SenorFunkyPants]

Originally Posted by SoreHead

Different gearing will always give difference consumption.

No doubt but the urban and extra urban cycles are run at quite low speeds, the combined average is something like 25mph, so any diference in consumption due to slightly differing gearing is at best notional.

[JCtx]

Originally Posted by southlight

Getrag website and they're stating the clutch operation is hydraulic.

If you're not using your foot, can't be hydraulic only (like a manual clutch); it needs an electric motor to replace your foot, no matter what you call it, but the correct term is 'electrohydraulic'. Think about it. The principle is the same: a slave cylinder pushing on a pressure plate to disengage the clutch. Good day.

[dcstep]

Originally Posted by SoreHead

How does the 4.10 affect the car generally? I was speaking to someone about modding recently and they mentioned it but I'm not spending that sort of money without knowing what I get for my money.

Mainly you gain acceleration in mid-gear. For street, it makes 2d, 3d, 4th and 5th really flexible. If you didn't want to, but why wouldn't you want to, you can do much passing without downshifting. I call it the "squirt factor" in traffic, where the car just squirts into spaces more easily and quickly.

It makes 2d gear significantly stronger for autocross, which I do and find supremely useful. The gas mileage drops 6+% for negative number one. Negative number two is that the already too short first gear is even shorter, so you only need it to start on a hill. However, that's overcome with an adjustment in driving style. I tend to rev 1st to 3000 thru 5000 rpm, then jump to 3d, then jump to 5th for driving where speed limits are 45 mph. Still, an adjustment in tranny gears would be ideal, but that's not in the cards.

You can hear a little more gear whine on the over ride at certain speeds. It seems to have lessened as I had the fluid changed after 1200 miles and as it gets more wear. I was showing my AA exhaust and car to a new friend and I couldn't get the final drive to whine. So, it's there, but not really a big negative.

I was highly motivated by the perceived AX gain, but I think it's a good mod for those just looking for street performance gain.

Dave

[SenorFunkyPants]

Originally Posted by southlight

Regarding actuation, I checked the Getrag website and they're stating the clutch operation is hydraulic.
Best regards,
south

I understand the clutch packs are held closed under hydraulic pressure.
It would seem logical to think that the high speed clutch engagement of the DCT is far more efficient than the slower MT clutch system which is surely more energy lossy.

[330CIZHP]

Originally Posted by SenorFunkyPants

I understand the clutch packs are held closed under hydraulic pressure.
It would seem logical to think that the high speed clutch engagement of the DCT is far more efficient than the slower MT clutch system which is surely more energy lossy.

To quote someone who has done extensive study in manual vs DCT:

Originally Posted by swamp2

Manual < dry clutch DCT < wet clutch DCT < torque locking auto < traditional auto.
.

In my opinion, manual will always be more efficient in terms of drivetrain loss than electronically managed clutch transmissions simply because it is far less complex.

[southlight]

Originally Posted by elp_jc

If you're not using your foot, can't be hydraulic only (like a manual clutch); it needs an electric motor to replace your foot, no matter what you call it, but the correct term is 'electrohydraulic'. Think about it. The principle is the same: a slave cylinder pushing on a pressure plate to disengage the clutch. Good day.

I'm fine with the term electrohydraulic. It's good we now agree that the actuation is not electromechanical.

Originally Posted by 330CIZHP

To quote someone who has done extensive study in manual vs DCT:

In my opinion, manual will always be more efficient in terms of drivetrain loss than electronically managed clutch transmissions simply because it is far less complex.

Great, Swamp is agreeing, so we can't be that wrong.


Best regards,
south

[kenwelch]

Powering the hydraulic pump also makes the M-DCT less efficient than a manual transmission. The M manual transmission does not use a hydraulic pump.

A gear driven pump is used to provide hydraulic pressure for the (dual) clutch application, shifting, and fluid cooling. The pump is driven using engine power and is an external tooth design. The pump pressure is variable and controlled electronically based on demand. The normal hydraulic pressure ranges from 5 to 20 bar and can be allowed to go as high as 30 bar. Turning the hydraulic pump takes energy.

You can see the pump drive gear in the center of the picture.

[SenorFunkyPants]

So what accounts for the 5% better fuel economy and lower C02 emissions?

[330CIZHP]

Originally Posted by SenorFunkyPants

So what accounts for the 5% better fuel economy and lower C02 emissions?

Simple. A very tall 7th overdrive gear and overall less aggressive final drive (3.32 vs 3.8 ).

[Paddy]

Originally Posted by 330CIZHP

6 speed manual. There is nothing more involving than feverishly working out both your arms and both your legs, especially when you are young.

What is most fun to me is how much passengers too enjoy watching and experiencing a good driver exhibiting his best driving skills like heel-toes and perfectly crisp rev-matches. It is almost they are getting entertained by your skills and admiring how you are working hard to make the car working the way you want it too.

Too true, and the sweet feeling you get when you hit those heel and toe downshifts just right, on a hard corner.

[smmmurf]

Even assuming that 5% better fuel economy is true, it takes about 250,000-300,000 miles to recover the initial cost of DCT (assuming $4/gal and 14-16mpg). By the time you get there, you will probably need a new DCT box.

At least it will be 5% more economical on the way to the dealer and back for DCT software updates.

[moog55]

DCT