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VW Introduces New TSI Engine and 7-Speed DSG Gearbox; More Power, Less Fuel

27 April 2007

VW introduced a new member of its turbocharged gasoline direct-injection TSI engine family at the Vienna Motor Symposium: a 1.4-liter, 90 kW (122 hp) version that develops up to 200 Nm (148 lb-ft) of torque.  The company also introduced a new 7-speed double shift gearbox (DSG).

With a 7% increase in power compared to the normally aspirated 1.6-liter FSI engine, the new TSI delivers a 30% increase in peak torque, while reducing fuel consumption by about 6%.

VW based the new engine on the higher-power Twincharger units in the TSI family (earlier post), but does not use the supercharger in addition to the turbochargers as they do.

The new seven-speed DSG, which unlike the six-speed DSG uses a dry sump, also offers better efficiency.

VW will apply both technologies in the Golf for an estimated fuel consumption of 5.9 l/100km (40 mpg US).

April 27, 2007 in Engines, Fuel Efficiency | Permalink | Comments (16) | TrackBack (0)

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Great! Does VWoA have any plans to offer the 1.4 TSI in the US market?

I applaud VW for bringing smaller direct-injection turbocharged engines to market. In the near future all ICE will be "right-sized" for performance AND economy.

Not sure about the 7spd. Wouldn't a CVT be better suited to extract the best performance from this smaller power mill?

[quote]Not sure about the 7spd. Wouldn't a CVT be better suited to extract the best performance from this smaller power mill?[/quote]

i believe CVT tranmission rob efficency and power losses when transmitting the power from the engine to the wheels, I believe the most efficent use of power transfer is still the standard 5spd with a clutch although AUDI's system is a more advanced computerized version of that.

Even though CVT is in the sweet powerband of an engine doesn't nesssary mean its transfering all that power to the wheels at good efficency.

Rubber band feeling one might say.

40 mpg! , there have been Golfs around for years that return
this sort of mpg . In the mid ninetees I ran a passat 2 litre 16v
estate ( the high performance golf engine at the time in a bigger
body shell) that car would return 6.8 - 7 litre /100km on a good
run and at motorway speeds 120-130 km/h , so 5.9 litres /100km
does not seem much of a triumph !
I guess you just cannot get around that old ICE inefficiecy!

In 7th on the interstate/autobahn it might get better than the one kmh/h mpg estimation.

What would Rafael think? I'll take a stab, the seven speed would be more effecient that the cvt, unless the cvt is perfected. And please, don't call the Prius "Transmisson" a cvt. The Prius doesn't even have a transmisson in my book....Raf?

God Bless! Ain't it good to be an engineer during these golden days of the ICE car? The ICE has been around since the original non-horse buggy was patented by Benz in 1886. And, boy! what progress we've made in the short time of 120 years. Why today you can buy a gasoline ICE car that has reached an efficiency level of somewhere around 30%. And, if it were not for the need to clean up emissions, we could almost reach 35%.

Is it time to start implementing zero-gearing, direct electric drive motors; or, should we wait until Hell freezes over and the Earth uses the heat to become Waterworld?

Typically, a fixed gear transmission has an efficiency of somewhere around 97-99%, perhaps 96-98% when taking into account the transient power loss in the clutch during shifting. Typically, the more gear ratios your transmission has, the longer can the engine be run in it's sweet (consumption) area.

However, more gears also mean an increase in the number of gear shifts. The highest number of gears I've seen so far is 8 (fwd) - i guess thats about as many as there will ever be, before diminishing returns limits this (both on efficiency and economics).

CVT, otoh, typically have limited torque transfer capability, and suffer from a lower efficiency (basically slip). Also, CVTs have a higher wear at high pretension forces necessary to transfer torque. Last I have learned, that a CVT transmission cann't be built using the same manufaturing line as conventional (manual) transmissions, whereas DSG (dual clutch) and shifted automatic transmissions do share a lot of common components (or at least the very same manufacturing line can easily adapted).

These factors make it very likely, that we'll see more 7-9 speed automated shifted transmissions (DSG or otherwise), but no CVTs.

I have not yet received my set of abstracts from the Vienna Motor Symposium, so I cann't comment if that engine could be cleaned up to meet FTP Tier 2 Bin 8 emissions levels (which is the minimum requirement for an introduction in the US).

What does it sound like ?
How much does it cost (on increase cost over a 1.6)
Could they build a smaller one, or tune it for lower fuel consumption and lower power ?
Could a user change the state of tune (dashboard switch) ?
7 gears is a lot of changing, you might want an automatic, especially for town use.

@ Bud Johns -

this variant of the 1.4L TSI features just a regular, fixed-geometry turbo that is small enough to deliver high torque at low RPM. The downside of this is that the wastegate has to be opened early, so rated power suffers a quite a bit compared to the much more expensive twincharger concept. Expect the latter to be phased out when VGT turbo technology becomes affordable for gasoline engines.

In the present fixed turbo-only variant, the objective is to reduce engine displacement for the intermediate power rating required for high-volume variants of the Golf et. al. In Germany and many other European countries the annual vehicle license fees are still based on engine displacement.

The other point of high torque at low revs is that you reduce internal friction losses in the cranktrain etc., which saves fuel (cp. also diesels). Also, at the moderate power levels required for cruising, a downsized engine running at high load will sound like a more expensive naturally aspirated one with 1.5-2x the displacement.

The trick, therefore, is to keep the engine operating in the portion of its engine map with relatively low SFC, over as wide a range of vehicle speeds and accelerations as possible. A large number of gears, preferably including one or two in overdrive, will let you do that. You pretty much have to kick down to accelerate properly, though, which would be tedious and uncomfortable with a stick shift. The DSG with wet clutches is much better suited to this task, because it can very quickly change gears under computer control while maintaining torque to the wheels. The wet clutches in the BorgWarner design that VW AG uses do reduce fuel economy by 3-4%. However, they don't wear out nearly as quickly as dry clutches would and, the transitions are smoother.

A CVT of some description would do an even better job of optimizing engine speed for a given power requirement. However, it suffers from a fuel economy penalty of 7-8%. The steel-belt-and-pulley mechancial CVT designs are also fairly loud and expensive to manufacture. Btw, the even more expensive electrically variable transmissions (EVTs), including the compound types used by Toyota and the GM/DCX/BMW alliance, are considered a subclass of CVTs.

@ mahonj -

the DSG *is* an automatic transmission, as is any device that automatically adjusts the transmission ratio. Mercedes has a seven-speed conventional AT with torque converter, but VW AG has decided it will gradually replace conventional ATs with DSGs across all of its product lines.

Most of the CVTs currently used as Rafael described (chain and pulleys) are demanding around 10 times the hydraulic pressure of a typical automatic transmission. Running this hydraulic system is part of where the great loss in efficiency happens.

@ Patrick -

correct, though it's worth pointing out that there are other CVT designs that require very little ancillary power and are therefore more efficient.

http://en.wikipedia.org/wiki/Continuously_variable_transmission

Two of the more interesting alternatives in recent years are from Germany. Both permit the use of a simple dry clutch for starting the engine and idling. The first is a modern implementation of the old cone-ring transmission concept that has been successfully employed by RWTH Aachen in the annual Formula Student championship (the European counterpart to America's Formula SAE). Testing for long-term durability is currently underway.

http://www.gif-ac.com/
http://www.ecurie-aix.rwth-aachen.de/

The following link is to a nice video animation. It's 140MB download, but worth the wait. Note in particular the mechanism for adjusting the contact pressure, the precession motion of the ring in response to a twist of the handlebar mechanism (20W electric motor), the direction reversal mechanism and, the use of regular transmission oil plus a special, viscous traction oil.

http://www.ecurie-aix.rwth-aachen.de/downloads/krganimation.mpg

The second is a variation on this theme based on toroidal curves rather than straight cones. This improves ring positioning accuracy at low vehicle speeds. Unfortunately, the project documentation is currently only available in German, put the illustrations should be enough to convey the general idea:

http://www.forschung.fh-konstanz.de/inhalte/Projekte/lege_trg_2006.pdf

good info guys, i love reading the comments... sometimes I learn more from the comments than the news article itself!

BTW can anyone rate the efficency rating of NISSAN's CVT's that are dominating their new cars?

Just because you have 7 gears doesn't mean that you have to accelerate through them all. I have been driving a miata around, which has 5 forward gears. When city driving, I often go from first to second to fouth.

Fourth gear leaves me going 35mph with the ability to accelerate and decelerate with only about 1700 rpm.

When driving in different conditions I would often like to shift to a nonexistant 2.5 gear.

Philmcneal:

According to Nissan brochure, they claim that over one million vehicles they sold with CVT are saving more fuel than 200 000 Priuses sold by Toyota. No more details were provided.

As far as I know, all of Nissan's CVTs are all supplied by Jatco of Japan. You can learn more about their transmissions from their web site than what Nissan will tell you. I haven't browsed it recently enough but I remember this web site being an interesting read.

http://www.jatco.co.jp/ENGLISH/index.html

The great thing about CVT remains that it optimally serves the engine which remains to be the main source of powerloss. The CVT enables the engine to run at roughly 24% efficiency over a typical cycle while a DCT (VW tradename DSG) only gets about 20% at the same cycle.
Vehicles with CVT can therefore easily match fuel consumption of vehicles with DCT. While the DCT at this moment has somewhat better efficiency at higher speeds, what matters in the end is what you have to put in your engine/tank. Transmission efficiency is not the same as fuel consumption.

For the future an increasing number of gears is foreseen. With only one gear/clutch being used and all the other ones running without transferring power and creating drag losses, burning energy while trying to shift between the gears, this will not help transmission efficiency. CVT has a benefit here. The power flow through the transmission is continuous and always runs through the same components. This not only offers optimal comfort but also simplifies control and calibration of both engine and transmission.
With the CVT components, unlike the clutches and gears, still offering large potential for efficiency improvement I foresee a bright future for this technology.

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