What is the purpose of a blow off valve (bov)?
The Blow-Off valve (BOV) is a pressure relief device on the intake tract to prevent the turbo’s compressor from surging from the backed up pressure waves caused by a suddenly closed throttle. BOV’s do not control boost levels. The BOV should be installed between the compressor discharge and the throttle body. When the throttle is closed rapidly, the airflow is quickly reduced, causing flow instability and pressure fluctuations. Airflow bounces off the throttle plate and the pressure waves can reverse direction. These rapidly cycling pressure fluctuations are the audible evidence of surge. Surge can eventually lead to thrust bearing failure due to the high loads associated with it. The BOV releases these pressure waves into the atmosphere when the throttle is closed during shifts or deceleration, creating an audible “woosh”. Blow-Off valves use a combination of manifold pressure signal and spring force to detect when the throttle is closed. When the throttle is closed rapidly, the BOV v
