Blow Off Valves

Engine » Blow Off Valves

Blow off valves

Blow-off valves (BOV) function to release pressure between the turbo and the intake manifold on forced induction engines.  When you let off the gas in a turbo charged engine, pressure created by the turbo is still present in the piping between the turbo and engine.  If this pressure is not released it can damage the turbo or other engine components.  Blow-off valves are mounted on the piping between the turbo and the intake manifold and serve to release this pressure when desirable.  As an added bonus, blow-off valves make an appealing whooshing noise when they release pressure, which can sometimes become criteria of the blow-off valve shopper.  On vehicles making especially high-horsepower it may be necessary to install more than one blow-off valve to accommodate the amount of pressure that needs to be released.

There are two separate styles of this particular component. Most turbocharged cars are equipped with a recirculating setup, which releases pressure back into the system. Many aftermarket products are of the atmospheric style, which releases the built up pressure into the air, creating a more noticeable sound. Depending on the vehicle and particular tune, an atmospheric blow-off valve may cause the car to run poorly. A recirculating valve is typically a safer option for relatively stock vehicles looking to improve the efficiency of the factory piece. Adjustable valves are available in some instances, allowing you to control the bias between recirculation and venting. If you are uncertain of which type of valve to choose, please don’t hesitate to contact us.