Turbochargers have their disadvantages, but Porsche has a unique way of solving them.
The way that turbochargers work, using the engine to spin a turbine which encourages more air into the engine to create a cycle of boost, takes quite a bit of time to get started. When it comes to responsiveness, a turbocharger is generally slower than a naturally aspirated engine or one with a supercharger. Traditionally, effective turbocharging requires compromise: a larger turbo helps at higher engine speeds, while a smaller turbo does a better job at lower speeds.
However, Porsche, since the 997 generation of the 911, has used the technology of a variable turbine geometry turbo, which uses vanes on the turbine to act as though the size of the turbocharger was changing depending on the engine speed. Jason Fenske from the Engineering Explained YouTube channel explains how the Variable Geometry Turbo in the Porsche 911 works and why it’s an ingenious solution to turbocharging’s problem.
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This technology was introduced to the automotive world in diesel cars in 1997, and the reason it took nearly a decade for the technology to be introduced in a gasoline car for the first time (in the 997 Porsche 911 Turbo in 2006) is that exhaust temperatures in a gasoline engine is much higher than in a diesel. The small parts involved in these systems are difficult to maintain surrounded by such high temperatures, so the engineering and materials involved are very specific and difficult to execute to make a reliable variable geometry turbocharger for a gasoline engine.
The current generation of the Porsche 911 Turbo S, the 992, thanks to this technology, makes up to 640 horsepower and 590 lb/ft of torque. The greatest bonus of the Variable Geometry Turbo is the fact that at peak power, you still have an estimated 500 lb/ft of torque. The 992 Porsche 911 Turbo S also has a symmetrical design to the turbochargers, meaning the flow is cleaner and more efficient than in the 991 generation, where the air didn’t flow quite as neatly. It’s no secret that the Porsche 911 Turbo S is an incredible machine, but learning how it’s able to achieve its incredible performance makes it even more special.
Source: Engineering Explained