What is Twin-Scroll Turbo?
2 Answers
Dual turbo refers to twin-turbocharging. Twin-turbocharging is one of the turbocharging methods. To address the turbo lag phenomenon in exhaust turbocharging, two turbochargers are connected in series (one large and one small) or in parallel (two identical ones). At low engine speeds, less exhaust gas is sufficient to drive the turbo to rotate at high speed, generating adequate intake pressure and reducing the turbo lag effect. Below is more related information: 1. Twin-turbocharging principle: When the driver presses the accelerator pedal, the engine speed changes. Due to the inertia of the turbine and compressor, they cannot immediately follow this speed change, a phenomenon known as "turbo lag." This "turbo lag" causes a delay in the engine's ability to increase or decrease power output. The harder you accelerate, the more you feel the engine struggling. Using twin-turbocharging means employing two independent turbochargers in the boosting system. When the engine operates under the combined effect of both turbochargers, intake efficiency is significantly improved, the boosting effect becomes more pronounced, and power performance is greatly enhanced. 2. Low engine speed: On the other hand, at low engine speeds, only one low-speed turbo operates. At this point, less exhaust gas is needed to drive this turbo to rotate at high speed and generate sufficient intake pressure. When the engine speed increases, the high-speed turbo kicks in, maintaining a high boost state and providing consistent, strong power. Thus, twin-turbocharging technology not only improves engine power performance but also mitigates the "turbo lag" phenomenon. However, twin-turbocharged engines cannot completely eliminate "turbo lag," as the inertia of the turbocharger impeller still exists. In practical applications, twin-turbocharged engines are typically equipped on larger displacement engines, such as inline 6-cylinder or V-type configurations.
I've been repairing cars for decades and have seen many turbochargers. The twin-scroll turbo is essentially an upgraded version. Unlike a regular turbo with only one exhaust outlet, it has two separate exhaust passages, each connected to different sets of cylinders. The benefit of this design is that when the engine exhausts, the gases don't interfere with each other, allowing the turbo to respond earlier, especially during low-speed acceleration, which feels particularly satisfying. For example, in some sports models I've worked on, like certain German cars equipped with this system, owners report much quicker starts, and city driving from traffic lights no longer feels sluggish. The downside, however, is that the construction is more complex, making repairs more troublesome, and it's prone to clogging due to exhaust carbon buildup. If your car has turbo issues, I recommend regular cleaning of the pipes to avoid affecting its lifespan. Overall, this technology really boosts performance, but it demands higher maintenance. When choosing a car, you might consider models with a twin-scroll turbo.
