VW's new "SuperTurbo" system

[politicophile]

Autoweek Article

Volkswagen will reach into the past for a combined supercharger-turbocharger system to boost power and fuel economy in its small gasoline engines.

The system, dubbed SuperTurbo Compounding by supercharger supplier Eaton, eliminates turbo lag while boosting overall power and fuel economy by 15 to 20 percent. Eaton, the apparent supplier of the supercharger for the engine, says a car fitted with the system will likely be shown at the upcoming Frankfurt show.

The article goes on to say that VW's 1.4L SuperTurbo will put out 140hp/184 lb-ft in base form and 170hp/199lb-ft when better tuned. But it gets better: the 1.6L has 195hp and the 2.0L has 240hp!

The beauty of this system, in my mind, is that the torque output is so large. Inline fours aint exactly known for their massive torque, but this system seems to compensate for that shortcoming, whilst also avoiding turbo lag. I drive a WRX, one of the finest four-cylinder engines available and one that isn't short of torque (217 lb-ft), but I do get tired of the turbo lag. I can only imagine what this system would do if applied to, say, a 911 Turbo or a Corvette ZO6...

[shazbotus]

Nice, sounds pretty impressive. I'm a bit of an auto newb, so is there a good site the explains how this sort of system (or auto mechanical systems in general) works.

[politicophile]

Originally Posted by shazbotus

Nice, sounds pretty impressive. I'm a bit of an auto newb, so is there a good site the explains how this sort of system (or auto mechanical systems in general) works.

I'd start here. That page contains links to pages explaining a wide variety of automotive systems. There are lots of diagrams and stuff is explained very well.

[Turbotom]

By the sound of it, it's nothing new. It's called a turbo compound supercharger. They were used on WWII planes. I'm not sure how VW's system will work, but on the planes, the crankshaft would spin the geared supercharger, so it's powered like a supercharger, but it also has exhaust gas runing though it. (Warning, I'm pulling some of these numbers out of my ass.) A normal gas engine is about 7.5% efficient, turning heat into mechanical energy. A supercharged engine is about 10% efficient (depending on the type of supercharger.) A turbo is about 14% (again, depends on type.) Turbo compound is supposed to be around 17%. The only reason it hasn't been used on a car is that it's needlessly complicated, but with the advent of hybrid cars, no one seems to care about needlessly complicated anymore.

One last little thing, a turbocharger is a supercharger...it's just a certain type. Supercharger is basically a category, and there are many different types.

[Martian]

Turbotom, true that a turbo is a type of supercharger, but generally supercharger is used today to refer specifically to the belt driven sort to avoid confusion (and having to say belt driven super charger all the time as it's a mouthful).

In other words, <hippy>get with the times, maaan!</hippy>

And yeah, hardly anything new. Not precisely common, but not new.

[TheOtherDave™]

You know, the Group B Lancia Integrale S4 used a compound turbo / supercharger system. But given the design of modern intermediate-sized turbos [like Garrett's GT28RS], I wonder if it's truly necessary.

Using the SR20DET as an comparison to VW's new 2.0T, the GT28RS can be spooled by 2800rpm and flow enough air to make about 350hp.

---
And on a related note, yes, a lot of petrol's energy is wasted as heat, but a turbo helps recover a considerable amount of energy from the exhaust stream. The supercharger OTOH, places a parasitic load on the engine that increases with RPM.
So again, you wonder, why bother?

[Turbotom]

Originally Posted by Martian

Turbotom, true that a turbo is a type of supercharger, but generally supercharger is used today to refer specifically to the belt driven sort to avoid confusion (and having to say belt driven super charger all the time as it's a mouthful).

In other words, <hippy>get with the times, maaan!</hippy>

And yeah, hardly anything new. Not precisely common, but not new.

But there are also different types of superchargers, such as the classic roots type, whipple type, and the centrifugal superchargers...which has a compressor much like a turbo.
However, I've discovered that axial compressed air (as in, roots type) is more efficient (cooler) than centrifugal, but I've only heard this in reference to aircraft turbines.

[EULA]

Hmm...let me guess here.

1. loud
2. unreliable like most VWs