What does twin-scroll mean?

[JudahAnn]

Twin-scroll refers to the exhaust turbine having two scrolls. A turbocharger consists of two parts: one is the exhaust turbine, and the other is the compressor turbine. When the engine reaches a certain speed, the exhaust has sufficient energy to drive the exhaust turbine, causing it to rotate, which in turn makes the compressor turbine rotate as well. Once the compressor turbine starts operating, it can compress air and force it into the cylinders, thereby enhancing the engine's power. Twin-scroll engines are typically found in four-cylinder or six-cylinder configurations. In a four-cylinder engine, the shape of the exhaust manifold is modified so that two cylinders share one scroll, while the other two cylinders use another scroll. This design helps reduce exhaust interference between the four cylinders.