When Does Turbocharging Kick In?
1 Answers
Turbocharging intervention is specifically related to engine displacement, with larger displacements resulting in lower intervention RPMs. The turbocharger in an engine engages at a certain RPM threshold, typically around 1000 or 1500 RPM for most vehicles. When the RPM drops below this threshold, the turbocharger disengages. This is why turbocharged engines often experience a slight lag of a few tenths of a second during acceleration, which is the time it takes for the turbo to engage. Below is relevant information about turbocharging: 1. A turbocharger can be viewed as a blower connected in series to the intake manifold. As long as the engine is running, exhaust gases drive the turbine, which in turn rotates the compressor impeller on the same shaft. At low RPMs, the turbine spins slowly, resulting in poor air compression. During this time, the intake manifold is in a state of negative pressure, and the turbine blades offer resistance to airflow rather than pressure. 2. When engine RPM increases, the turbine wheel spins faster due to exhaust gas flow, gradually increasing the thrust generated by the turbine blades. For example, after reaching 1200 RPM, this pressure exceeds the suction created by the engine pistons, causing the intake manifold to experience positive pressure as the blower continuously forces air into it. This 1200 RPM is what's known as the "intervention RPM" – essentially the positive pressure threshold of the turbocharger. Once the turbo reaches this RPM, the pressure it generates surpasses the suction created by piston intake and exhaust. This RPM is commonly referred to as the "intervention RPM." 3. The so-called intervention RPM of a turbocharger is determined based on factors such as the engine's base displacement, power requirements, and maximum cylinder pressure, achieved through the turbo's size (inertia). Smaller turbo inertia means the turbine spins up quickly with minimal exhaust gas flow, while larger turbo inertia makes it relatively more difficult for exhaust gases to increase turbine RPM.
