Saab Technology

Engine Technologies: Variable Twin Scroll Turbocharger

BorgWarner Twin scroll turbocharger

Variable Geometry Turbochargers and Twin Scroll Turbochargers each have their own unique advantages, but what if you could combine the technology together?

Borgwarner  (known for TwinTurbo in Saab 9-3 TTiD) has developed a turbocharger concept where a twin scroll turbocharger has a valve which can redirect exhaust airflow into just a single scroll, or vary the amount the valve opens and allow for the gases to completely split between the two scrolls.

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The disadvantage of variable geometry turbochargers is that they are too expensive for gasoline applications because the materials have to be strong enough to withstand the high exhaust temperatures resulting from gasoline combustion.

Diesel applications tend to have lower exhaust temperatures so the technology is far more common with diesel engines. By implementing a valve with the twin scroll turbo, it can act very similarly without worrying about exotic materials to make it work in gasoline engines.

Goran Aničić
the authorGoran Aničić
For over 10 years, Goran Aničić has been passionately focused on Saab automobiles and everything related to them. His initial encounter with Saab cars took place back in 2003 when the first Saab 9-3 and sedan version were introduced. At that moment, he was captivated by the car's Scandinavian design logic and top-notch engineering, and everything that followed stemmed from that first encounter. Later on, through his work at the editorial team of the Serbian automotive magazines "Autostart" and later "AutoBild," he had the opportunity to engage more closely with Saab vehicles. In 2008, he tested the latest Saab cars of that time, such as the Saab 9-3 TTiD Aero and Saab 9-3 Turbo X. In 2010, as the sole blogger from the region, he participated in the Saab 9-5ng presentation in Trollhättan, Sweden. Alongside journalists from around the world, he got a firsthand experience of the pinnacle of technological offerings from Saab at that time. Currently, Goran owns two Saabs: a 2008 Saab 9-3 Vector Sportcombi with a manual transmission, and a Saab 9-3 Aero Griffin Sport Sedan from the last generation, which rolled off the production line in Trollhättan in December 2011.

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