When Does Turbocharging Kick In?
1 Answers
Turbocharging intervenes when the engine reaches its maximum torque. This is because if the engine speed is too low, it becomes difficult for the turbo to function effectively. Moreover, with insufficient exhaust flow, the power output of a turbocharged engine would be similar to that of a naturally aspirated engine. Therefore, turbocharging does not provide sufficient power at low speeds, and its intervention at maximum torque yields the best results. For example, if an engine's maximum torque range is 1800~3500 RPM, once the engine exceeds 1800 RPM, it reaches its maximum torque. At this point, during overtaking or acceleration, when the engine speed surpasses this threshold, the engine delivers its most powerful performance to facilitate rapid acceleration. However, the maximum torque and RPM range vary for each engine. Some turbocharged engines might have a range of 2000~4500 RPM, which is related to the size of the turbo. Larger turbos experience delayed RPM increases, which in turn affects the engine's performance. For typical family cars, turbo intervention occurs earlier to minimize turbo lag. Even at low speeds (1000~1500 RPM), the engine can maintain high torque. A turbocharged engine operates by utilizing the inertial force of exhaust gases to drive a turbine in the turbo chamber. This turbine, in turn, drives a coaxial impeller, which compresses air delivered through the air filter and forces it into the cylinders. Essentially, it functions like a blower connected in series to the intake manifold. As long as the engine is running, exhaust gases spin the turbine, driving the compressor impeller on the other end of the shaft. At low engine speeds, the turbine spins slowly, resulting in poor air compression, and the intake manifold remains in a state of negative pressure. Here, the turbine blades only create resistance without adding pressure. As engine speed increases, the turbine spins faster due to the exhaust gases, gradually boosting the thrust generated by the turbine blades. This shifts the intake manifold into positive pressure, with the blower continuously forcing air into it, thereby providing the vehicle with additional power.
