Why is there a loud air release sound when the turbocharger throttle is released?

[Smith]

Turbocharger throttle release produces a loud air release sound due to the operation of the blow-off valve. Here are the reasons: 1. Turbocharger working principle: When the turbocharger starts working upon throttle application, it compresses a large amount of air and pushes it through the throttle into the engine combustion chamber. When the driver releases the throttle pedal, the throttle closes. However, the turbocharger blades do not stop working immediately, leaving residual compressed air in the intake pipe between the turbocharger and the throttle. If this air is not released promptly, the high pressure can damage the throttle and turbocharger blades. 2. Blow-off valve function: The blow-off valve opens when it detects excessive air pressure in the intake pipe, releasing the residual compressed air to protect the throttle and turbocharger blades. This also reduces turbo lag, making the engine run more smoothly. The air release sound you hear is the 'noise' generated when the blow-off valve discharges the compressed air.