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Porsche Announces Variable Turbine Geometry (VTG)
Monday, 14 November 2005

Porsche's next-generation 911 Turbo to feature Variable Turbine Geometry (VTG), advancing the flexibility and efficiency of the 100-year-old invention.

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Constantly at the forefront of turbo technology, Porsche will once again propel turbocharging to the next level. November 16, 2005 marks the 100th anniversary of the invention of the turbocharger, a device that has only added to Porsche’s storied racing and performance legacy. To recognize this landmark date, Porsche announces its latest turbocharging development: Variable Turbine Geometry (VTG).

In its next iteration, the Porsche 911 Turbo will offer VTG, a mechanism that continuously adjusts the angle of the compressor’s turbine blades, a world’s first for a turbocharged gasoline engine. Featured in diesel engines since the early 1990s, VTG can provide significant improvements in engine flexibility and responsiveness, particularly at low engine speeds. Until now, this innovation has been limited to diesel applications, due to the far higher exhaust-gas temperatures (up to 1000° C/1800° F) prevalent in turbocharged gasoline engines. But Porsche has overcome this hurdle—working in close cooperation with Borg Warner Turbo Systems—by using temperature-resistant materials derived from aerospace technology.

The core feature of the VTG system is the variable turbine blades, which articulate to most effectively guide the flow of exhaust gases from the engine onto the turbocharger’s turbine wheel. The principle behind variable turbine geometry is to combine the benefits of a small and large turbocharger in one unit. This ensures both responsiveness and high torque at low engine speeds, while providing superior output and performance at higher engine speeds. Another benefit is a large torque plateau maintained throughout a much wider rpm range.

A Compressed History

Swiss engineer Dr. Alfred Büchi invented the exhaust gas turbocharger 100 years ago, receiving a patent on Nov. 16, 1905 for a "combustion machine consisting of a compressor (turbine compressor), a piston engine, and a turbine in sequential arrangement." Büchi used the exhaust gas flowing out after the combustion process to drive a turbine, which in turn drove a compressor to boost the amount of engine intake air. The first application of turbocharger technology was in the 1920s on large marine engines, with the first attempts to use this technology in the automobile beginning in the late '50s.

In 1973, Porsche campaigned the 917/30 in the North American Can-Am Series. This fearsome machine developed more than 1100 horsepower, and as a spearhead for turbocharger technology in the United States, the ultra-powerful racecar overwhelmed its opponents on the track. The outcome was a regulations change in the Can-Am Series that sent the almighty 917/30 straight to the museum.

Since then, Porsche has constantly strove to advance turbocharging applications. The Porsche 911 Turbo burst onto the scene at the Paris Motor Show in 1974 as the world's first series production sports car with an exhaust gas turbocharger. Porsche has continued to advance turbocharging technology in each generation of “the Turbo”—the intercooler, bi-turbo, VarioCam® Plus, as well as the "Cleanest Car in the World" title—that have all set benchmarks in turbocharger development. Now the next generation of the Porsche 911 Turbo is clearly spelled out in three letters: VTG.

Since arriving on this continent in 1976, Porsche enthusiasts have been particularly smitten by the 911 Turbo. Of the more than 50,000 Porsche 911 Turbos produced in Stuttgart-Zuffenhausen, over 20,000 have been sold in North America.

 
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