What is Turbo Lag?

To address the question, "What is turbo lag?" it's helpful to first understand what a turbo is and how it functions. In essence, a turbo, or turbocharger, is a device designed to boost an engine's horsepower and efficiency by injecting additional compressed air into the engine.

What causes turbo lag?

To channel compressed air into the engine, the turbocharger must collect exhaust gases to spin its turbines and generate pressure. Spooling a turbocharger takes time as the engine revs up, pushing more exhaust gas pressure into the turbo. 

When driving a turbocharged car at low RPMs, pressing the accelerator won't immediately engage the turbocharger, as turbo lag is more noticeable at lower RPMs. However, as the engine's RPMs increase, the turbo will spool up, producing enough compressed air to enhance engine power output.

Why can’t standard turbochargers operate at a lower RPM to avoid turbo lag?

Turbochargers find their optimal function as a balance between size and performance. A turbocharger small enough to generate power at low RPMs may lack the durability to withstand full throttle and higher RPMs, potentially leading to catastrophic failure and engine damage. Conversely, oversized turbochargers that aren't suited to the engine's RPM range won't provide boost until reaching higher power levels. Although this setup increases peak power, it also amplifies turbo lag, as higher RPMs are needed to spool and engage the turbo.

Typically, the turbocharger selected for a specific car is designed to activate within the middle of the engine's powerband, ensuring safe and effective power delivery. Some modern high-performance vehicles feature advancements like Twin-Scroll turbochargers, which aim to eliminate turbo lag entirely. While some turbo lag is expected in turbocharged vehicles, an unusual increase in lag or a significant power loss could indicate a problem with the turbo system.

If this is something you’re experiencing, be sure to get your car booked with an expert mechanic on AutoGuru. It’s the easiest way to find local, high-quality mechanics who you can easily book online!