The Blow-Off valve (BOV) is a pressure relief device on the intake
tract to prevent the turbo’s compressor from going into surge. The BOV
should be installed between the compressor discharge and the throttle
body, preferably downstream of the charge air cooler (if equipped).
When the throttle is closed rapidly, the airflow is quickly reduced,
causing flow instability and pressure fluctuations. 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. 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 vents boost in
the intake tract to atmosphere to relieve the pressure; helping to
eliminate the phenomenon of surge.
tract to prevent the turbo’s compressor from going into surge. The BOV
should be installed between the compressor discharge and the throttle
body, preferably downstream of the charge air cooler (if equipped).
When the throttle is closed rapidly, the airflow is quickly reduced,
causing flow instability and pressure fluctuations. 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. 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 vents boost in
the intake tract to atmosphere to relieve the pressure; helping to
eliminate the phenomenon of surge.