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VW Intros New Dual-Charged, Downsized Engine Family (TSI) at Frankfurt

25 August 2005

VW is introducing the first of a newly-developed gasoline engine family that combines downsizing with dual charging (super- and turbo-) to provide high power output and maximized torque with low fuel consumption.

The first such dual-charged engine from the new TSI family (VW’s current main gasoline engine line is the FSI) will be the 1.4-liter version in the new Golf GT 1.4 TSI, to be introduced at the 61st International Motor Show (IAA) in Frankfurt in September.

FSI vs. TSI
Golf GT 2.0 FSIGolf GT 1.4 TSITSI %
Cylinders 4 4
Displacement 2.0 liters 1.4 liters -30%
Power 110 kW (148 hp) 125 kW (168 hp) +14%
Torque 200 Nm 240 Nm +20%
Fuel consumption 7.6 l/100km 7.2 l/100km -5%
Fuel economy 31 mpg US 32.7 mpg US +5%

The 125-kW (168 hp) four-cylinder 1.4 TSI delivers maximum torque of 240 Nm (177 lb-ft) with a combined cycle fuel consumption of 7.2 liters/100km (32.7 mpg US).

By contrast, the current 2.0-liter GT FSI offers 110 kW (148 hp) of power, 200 Nm (148 lb-ft) of torque, and 7.8 l/100km (30 mpg US) fuel consumption.

VW will also preview a new Touran using the TSI engine. The Touran 1.4 TSI is a lower-performance version, offering 103 kW (138 hp), and is due to launch in Germany in the first quarter of 2006.

Combustion in an engine is limited not by the amount of fuel that can be injected but by the amount of air an engine can suck in to mix with that fuel. Forcing compressed air into the engine allows more fuel to be burned, resulting in higher output than from engines of the same size, but that are naturally aspirated.

Both superchargers and turbochargers are designed to provide that compressed air to boost output, but they do so quite differently. A supercharger is a compressor driven by a belt, chain or gears—and hence can react quickly to start-up or low-speed acceleration. A turbocharger uses the otherwise wasted heat energy of the exhaust gases to spin the fans that compress air entering the engine’s intake manifold.

But superchargers put a parasitic load on the engine, and turbochargers can have a lag time (“turbo lag”) as the fans come up to speed.

Combining the two (compound, or dual charging) provides the best of both. In the new combined system, the mechanical compressor operates at low engine speeds to increase low-end power. At middle revs, the turbocharger will engage. Once the turbocharger reaches sufficient speed to provide boost, a clutch will disengage the supercharger, which will then be bypassed.

That’s tricky to accomplish well, but is made more approachable by the increasing sophistication of engine management software and systems.

In and of themselves, neither turbochargers or superchargers increase fuel economy. It’s the opposite—they are designed to support increased fuel burn, resulting in more power.

But the additional power enabled by a super-, turbo- or compound-approach enables the use of a smaller engine for the same application. In other words, even though the charging systems burn more fuel, by applying them in a smaller (downsized) engine, the automakers can deliver equivalent (or even better) power compared to a larger system, and as a result see a net gain in fuel economy.

That’s exactly what you see in the comparative output of the two Golf platforms above. The 1.4-liter TSI outperforms the 2.0-liter FSI, while using less fuel.

We’ll do more on super-, turbo- and compound-charging following the Frankfurt show.

August 25, 2005 in Engines, Fuel Efficiency, Vehicle Systems | Permalink | Comments (10) | TrackBack (0)

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Comments

Oops moment: "Both superchargers and turbochargers *are designed to designed to* provide that compressed air to boost output"

Thanks, eagel...eagul...uh, eagle eye!

"The 1.4-liter TSI outperforms the 2.0-liter FSI, while using less fuel."

That's the kind of innovation I want to see more of! Props to VW.

Sounds like there is too much vehicle weight to only get USmpg
in the 30's. A 1997 Civic 1.6 liter HX gets 45 mpg highway. I
think the engineering of the entire vehicle appears to be lacking in this case.
I do not want to pay for "performance".

This certainly shines a light on U.S. manufacturer's claims that increasing CAFE standards can lead only to smaller vehicles with less power. VW takes the same vehicle and increases mileage AND power.

Anymore it seems like foreign manufacturers are the only ones showing what we used to like to call "American Ingenuity." Pity.

This sounds like a great idea. Hopefully they will bring the same concept down into more "normal" power engines as well (I don't need 125 kW in a Golf sized vehicle. My father has a Golf Variant with a IIRC 70 kW engine, which IMHO is plenty for a vehicle of that size).

Also, a terminological nitpick. "Compounding", or turbo-compounding as it's frequently called, usually refers to the use of an additional turbine connected to the engine output shaft via a reduction gear. It was frequently used in late 1940:ies aircraft piston engines. IIRC Scania has also recently used the concept in some of the higher power truck diesel engines. To avoid any confusion, might I suggest the term "dual charging", as used by VW.

Jesse Jenkins - the reason that vehicles weigh so much in the US is purely for comfort reasons and marketing fluff. You want the 12-way speaker system, and 16-way airbag system for your car right? If you don't, you can't keep up with your neighbor's sound system, and your kids won't be safe.

Toyota managed to make the Prius II bigger, heavier, more powerful AND it gets better fuel economy. I bet they could reduce the engine displacement with a turbo, although I'm not sure if it would have much of an effect on fuel economy since it's very efficient as it stands.

The real reason why american cars are big is not confort, it`s the inflated way americans see themselves. European cars are much more confortable, consume lesse fuel, have more specific power and are far... far safer than the american bathtubs with wheels.

The new TSI engine sounds all very well, but it does sound like there's a whole bunch of things to go wrong!

If the clutch uses software to disengage the supercharger, I'm scared. I wonder how long it will be before these cars are re-called?

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