Volkswagen Unveils 272 HP 2-Liter Diesel Engine and 10-Speed DSG

[DieselOx]

I don't even care about a manual anymore. Heck, give me a CVT or a slush box, I'll leave it in manual mode and install a dummy clutch pedal so I can pretend.

 

[IndyHop]

268HP 2.0 liter TDI

http://www.topgear.com/uk/car-news/volkswagen-diesel-engine-innovation-workshop-2014-11-11

 

[DieselOx]

CVT might feel wrong, due to our habituation to the way a stick feels, but a robust CVT is far superior in every way. The engine is almost always in it's best RPM range for power and or efficiency. Perfect ratio for conditions is possible. Theoretically, a CVT can always beat a manual in accel times, efficiency. Actual real world has ben hit and miss, but latest iterations are close enough for me. I couldn't care less about the fiction of being more at one with the car. Grow up. Get me there as cheaply as possible.

 

[ymz]

Feh... only a 10 speed DSG? When are they going to get serious?


Y.

 

[Second Turbo]

Should I be at 3.478:1 or 3.473:1 ?

> ... a robust CVT is far superior in every way. The engine is almost always in it's best RPM range for power and or efficiency.

I've also seen it asserted that a CVT is never sure if it's at the optimum ratio.

I've also heard that they are noisy, and relatively short-lived due to the parts rubbing at slightly different speeds. My eyeball engineering raises an eyebrow at those cone-drive designs.

I can imagine a CVT that could be quiet and robust, such as a sliding shaft hydraulic pump/motor pair (not clear on efficiency, tho).

Of course, as DSG-like twin-spool transmissions raise their ratio counts to silly levels, they are also at risk of never being sure if they're in the optimum gear.

This all may be aimed at making us grateful when electrics makes the whole problem go away.

Meanwhile, a 5 speed manual would work for me.

 

[Ted Hurst]

For us old-skool guys, that's north of 36,000 psi...

Wow, I sell hydraulic hose, tube and fittings for a living. I wonder what the wall thickness is on the tubing and what style of tube connectors one would use for those pressures?

 

[Ted Hurst]

Feh... only a 10 speed DSG? When are they going to get serious?


Y.

It's like a silly razor blade war. These transmissions are going to spend more time shifting than anything else.

 

[bhtooefr]

However, with smaller steps between the ratios, the shifts can actually be faster, and it won't have the losses of a CVT.

 

[Joeym4692]

I would really love to see a 10 speed dsg in our cars. Depending on the gear ratio that could give us some really good highway numbers with fuel economy.
I wouldn't mind some more power than my 09 tdi has either!

 

[Chris B]

Meh...10 speed DSG. Gimme 15 or 18 gears along with two sticks to shift them!

Twin Stick Pappy

Seriously, this whole "look how many gears we have" bullcrap is getting a little nuts. I realize a wider ratio spread and smaller steps are better, but at what point do you reach the law of diminishing returns? 10, 12, 20? Shoot, take a wide ratio CVT and stick the planetary gear set out of an old Powerglide behind it. Depending on what your needs are, you could rig it up for either super low range or super overdrive.

I'll just keep my 5 spd...thanks.

Chris

 

[nicklockard]

Meh...10 speed DSG. Gimme 15 or 18 gears along with two sticks to shift them!

Twin Stick Pappy

Seriously, this whole "look how many gears we have" bullcrap is getting a little nuts. I realize a wider ratio spread and smaller steps are better, but at what point do you reach the law of diminishing returns? 10, 12, 20? Shoot, take a wide ratio CVT and stick the planetary gear set out of an old Powerglide behind it. Depending on what your needs are, you could rig it up for either super low range or super overdrive.

I'll just keep my 5 spd...thanks.

Chris

I disagree. Cars have been ridiculously undergeared for EVER. So many engines have a best efficiency island that is tiny, like 200 rpm's wide, sometimes less! The only way to keep on that island is with more gears or CVT.

 

[morpwr]

100 Extra Horsepower and Warranty

The extra 100 horsepower over a CR170 model is alot. I look at all the work people do to get 220 WHP or 270 crank horsepower. This engine must have alot more boost and RPM. If this is not stressing the motor that much, because they are offering warranty, what can we adapt to our daily driver? The PD motor has reasonable injection pressure. It could be raised with aftermarket oversize plungers. Could the variable cam timing from another car(Honda) be adapted, and would you notice. The electric supercharger is good to reduce the lag, but once the turbo is spooled, I presume the supercharger is deactivated. Any info on the big differences between a CR170 and this new motor, block, girdle, rods.etc, to stay together with this output?

 

[bhtooefr]

It's a new engine family, and VW tends to optimize everything lately.

It may also be lower compression, made up for with boost. And, they're not going to be pushing the revs that hard.

 

[2011tdiproject]

A 1L displacement TDI would not keep the 4-cylinders (thermal efficiency goes down as cylinder dimensions go much smaller) but rather go down to 2 or 3

I'm really trying to figure this out, not quite there yet. Say you have a cylinder of a certain displacement, then you scale that down to 1/4 of the size, and then have 4 of them. The 4 little cylinders have the same total displacement, same bore to stroke ratio, same total surface area, etc..right?

I've wondered about this for a while, tried to research it, got absolutely nowhere. But I can find examples in real life, like the big 4 cylinder diesel in the Isuzu NPR/chevy 4500 box truck. I believe those are 5.2 liters. There has to be some reason they use that over the duramax 6.6 V8.

 

[TDIMeister]

No, the surface-to-volume ratio worsens (increases) with smaller bore-stroke dimensions. This can be easily calculable using simple shapes (e.g. cubes and spheres, but cylinders are the closest and most representative geometry). It's not only the total swept dimensions of the bore and stroke but more important the surface-to-volume ratio at top-dead center around the time of fuel injection and combustion.

 

[2011tdiproject]

However, with smaller steps between the ratios, the shifts can actually be faster, and it won't have the losses of a CVT.

The gear spread doesn't matter much for the dual clutch shift times, since the computer engages that gear before it needs to shift anyway.

 

[bhtooefr]

But the clutch slip is what makes a DSG shift time, and there's less clutch slip with closer ratios.

 

[TDIMeister]

Closer ratios between gears allow less RPM drop at each shift, which means shifts can be more frequent, not quicker, to keep the engine operating at more efficient operating points in the BSFC map without causing the engine to drop to a such a low RPM that it doesn't have the output to maintain a desired accelerating thrust. This is the mechanism by which more gears (with the limit being an infinite number, as in a CVT, ignoring slip) gets better fuel efficiency. Clutch slip is modulated and there's an adaptive model-based routine in the control system for wear and rotating inertias, so this is not the limitation.

 

[2011tdiproject]

No, the surface-to-volume ratio worsens (increases) with smaller bore-stroke dimensions.

So I just did some math and the surface area to volume ratio does worsen with more cylinders of smaller displacement. I just took a cylinder 8cm wide, 10 tall, for a displacement of 502.4cc. Dividing that volume into 4 smaller cylinders yields 125.6. Then, 2.5 pi r cubed was how I figured out the dimensions of the smaller cylinder. Radius 2.5198, height 6.2995, surface area 139.5596. So 4 of those little cylinders have 558.23 square centimeters, vs 351.68 for the big cylinder. 1.58 as much surface area for the same displacement? Wow. Hopefully I did the math correctly..

 

[bhtooefr]

And now you know why the most efficient diesel engines are bigger than your house.

 

[2011tdiproject]

But the clutch slip is what makes a DSG shift time, and there's less clutch slip with closer ratios.

Yes, that is true, say you have 1 shift from 5000 rpm to 4000, or 2 shifts, the first one drops to 4500, then the second to 4000, if you the same slip rate, you'll have the same shift time for the single shift as the 2.

So you'll have a quicker time between gears, but same clutch slip time overall I guess? I don't know

 

[2011tdiproject]

The thing I'm most curious about with this thread/subject is how they got that 272 hp. With our ratio of 238 ft lbs / 140 hp, that would be 462 ft lbs, but I'm betting the peak torque is under 400 ft lbs. 272 hp at 4000 rpm is 357 ft lbs, I'm betting the torque curve looks more like that. Every time I drive my tdi I wish it had more usable power, maybe something can be taken from this engineering for our tdis.

 

[TDIMeister]

Because no real linear relationship exists between an engine's peak power and torque; with modern turbocharging and controls you can essentially tailor any shape of the torque curve you want. The realizable peak torque is often clipped from what's "possible" in the interest of transmission capacity (very much so in this case), or other more complex factors like emissions, engine durability (which do have relationships to the specific output) and strength limits on certain components as a function of the peak pressures that occur in the engine cylinders that are directly proportional to the developed torque and RPM.

 

[2011tdiproject]

with modern turbocharging and controls you can essentially tailor any shape of the torque curve you want.

Yeah, my guess based on quick math and what I read is they probably limited the torque in the peak of the powerband, but carried that number up to 4000 rpm or so to get that nice 272 hp. And of course a turbo that makes power like that won't spool early enough, so they used the e-assist.


I just wish they'd tailor the motors they sell in mass a little differently. Imagine something like a factory gtb2260vk option on the mk6 tdi. TDI-R. But they never do it that way. Even in the 2.0 tdi amarok, compounds for only 227 hp, if I remember correctly. I do not understand why they undersize the turbos on the tdi so badly. They're going into cars, not pickup trucks.

 

[bhtooefr]

The Amarok has been known to use compounds for as little as 160 PS, for what it's worth.

And, small turbos mean faster response, which is important for emissions.

 

[GoFaster]

I do not understand why they undersize the turbos on the tdi so badly. They're going into cars, not pickup trucks.

Partly it's because they know people actually drive in the lower part of the RPM range.

And part of it is emissions and "throttle" response. If you have a laggy turbo, the engine will be running off boost when starting off from a stop for much longer. These newer engines are capable of having significant boost pressure barely above idle.

 

[nokivasara]

If this is the same engine as in the new Passat we're getting here (240hp/500nm for us) it has a compression ratio of 15:1 or thereabouts.
With Mazda Skyactive gasser having 14:1 the engine types are getting closer and closer.
Who would have thought 10 years ago??

I don't know if I like this, the gassers are getting more fuel efficient and has good torque charasteristics, soon they'll be better than diesels

 

[atc98002]

If this is the same engine as in the new Passat we're getting here (240hp/500nm for us) it has a compression ratio of 15:1 or thereabouts.
With Mazda Skyactive gasser having 14:1 the engine types are getting closer and closer.
Who would have thought 10 years ago??

I don't know if I like this, the gassers are getting more fuel efficient and has good torque charasteristics, soon they'll be better than diesels

Ah, wait until the gassers get hit with some of the same emissions requirements that diesels have now, in particular the DPF filter. That will hit their MPG the same as it did for us.

 

[scrambld]

Do you need more than 370lbs of torque? my ALH vnt17 was around 375ft/lbs and it was plenty. All you need is a longer torque band not a short peak. With 10 (t e n) gears and a decent torque band the engine would be in peak power mode without the need for a crazy high torque peak surge.


My stage2 2013 was as fast as my more powerful ALH vnt17. Because it had better torque / power band and 6 gears. But the ALH was much more fun. Torque surge, smell, sound, smoke....

....you get used to what you have......and then want more.

I suppose you modded your ALH for that reason? I've never heard of anyone modding a common factory offering to get....... less?

I do agree on the "more gear" thing. I've said for years....it's like riding an old 3spd bicycle vs. a 21spd bicycle....which one is easier and more pleasant to ride over varying terrain (same power output...you the rider)? The 21spd is more flexible by far.

 

[993er]

Is the engine's torque band so narrow that it needs 10 speeds?