- The Washington Times - Thursday, December 15, 2005

When it was introduced at the 1974 Paris Motor Show, the Porsche 911 Turbo was the first production sports car with an exhaust gas turbocharger. Since its 1976 arrival in the U.S., more than 20,000 have been sold in North America.

The turbocharger was invented 100 years ago by a Swiss engineer, Alfred Buchi. His patent described it as “a combustion machine consisting of a compressor, a piston engine, and a turbine in sequential arrangement.”

Mr. Buchi used the exhaust gas flowing out of the engine to drive a turbine, which in turn drove a compressor to boost the amount of engine intake air. First used in marine applications, the turbo started showing up in cars in the 1950s.

In 1973, Porsche raced its turbocharged 917/30 in the North American Can-Am Series. It developed more than 1,100 horsepower and easily overwhelmed its opponents on the track. It was a great way to showcase turbocharging in the U.S., but the outcome of the race resulted in a regulations change in the Can-Am Series that sent the mighty 917/30 straight to the museum.

Porsche has continued to advance turbocharging technology in each generation of its 911 Turbo with features such as the intercooler, biturbo, variable cam phasing and more. Now, Porsche will once again propel turbocharging to the next level.

The next-generation Porsche 911 Turbo, due in September 2006, will offer Variable Turbine Geometry. VTG is a system that continuously adjusts the angle of the compressor’s turbine blades. VTG systems have been used in diesel engines since the early 1990s, but the Porsche application is the first for a turbocharged gas engine.

VTG can provide significant improvements in engine flexibility and responsiveness, particularly at low engine speeds.

Until now, VTG’s advantages have been limited to diesel applications where the exhaust gas temperatures are relatively low, compared with much higher temperatures in turbocharged gasoline engines. Working with Borg Warner Turbo Systems, Porsche has overcome the temperature limitation through the use of temperature-resistant materials derived from aerospace technology.

The unique feature of the VTG system are the variable turbine blades, which articulate to optimize the flow of exhaust gas onto the turbocharger’s turbine wheel. The blade angle is controlled by the engine management system. Turbochargers can be designed to operate best at high engine speeds, but performance at low speeds is compromised. The same can be said about designing for low speeds, while compromising high-speed operation. The big attraction of VTG is to combine the benefits of a small and large turbocharger in one unit.

Another significant side benefit is a large torque plateau that can be maintained throughout a much wider speed range.

Impressive as it is, Porsche has more than VTG to offer in 2006 models. The much-anticipated all-wheel-drive versions of Porsche’s latest 911 models have arrived.

The hardtop 911 Carrera 4 and 4S Coupe, and open-top 911 Carrera 4 and 4S Cabriolets, are easy to identify. Wider rear wheels and body panels flared nearly 2 inches beyond those of the two-wheel-drive 911 Carrera give the all-wheel-drive versions a more muscular stance.

For the first time, four-wheel-drive 911 Carrera models will be available with a choice of two engine options. Carrera coupes and cabriolets use the carryover 3.6-liter, 325-horsepower flat six. Carrera 4S models are equipped with a larger 3.8-liter engine, good for 355 horsepower. All Carrera 4 models are available with Porsche’s active suspension management system that allows the driver to switch from the comfort of a touring car to the precision of a track-ready sports car.

The Carrera 4 Coupe and Cabriolet are priced at $77,100 and $87,100, respectively. The Carrera 4S Coupe is $87,100, while the Carrera 4S Cabriolet lists at $97,100. No word yet on pricing of the new 911 Turbo — but it probably will be high.

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