Dewhel Universal V-Band Blow Off Valve

What kind of sound does a blowoff valve make?

The blowoff action produces a range of distinctive hissing sounds, depending on the exit design. Some blowoff valves are sold with a trumpet -shaped exit that intentionally amplifies the sound.

Why is it illegal to vent an unmuffled blowoff valve?

Motorsports governed by the FIA have made it illegal to vent unmuffled blowoff valves to the atmosphere. Blowoff valves are used to prevent compressor surge, a phenomenon that readily occurs when lifting off the throttle of an unvented, turbocharged engine. The sound produced is called turbo flutter (the slang term "choo-choo" is sometimes used).

When do blowdown valves open do they cause blowdown?

Upon initiation of an automatic blowdown, all blowdown valves (BDVs) should open and cause the blowdown of all offshore facilities. It is not intended that a facility-wide blowdown scenario should govern the required flare stack height.

How is a blowoff valve connected to a turbocharger?

When the throttle is closed, a vacuum forms in the manifold. This in combination with the pressurized air from the turbocharger moves the piston in the valve up, releasing the pressure into the inlet of the turbo (Recirc.) or the atmosphere (BOV). A blowoff valve is connected by a vacuum hose to the intake manifold after the throttle plate.


Machined from CNC aluminum alloy and featuring a large 50mm valve, the Dewhel is our best value pick due to its price as well as its universal use.

You get a lot of nice engineering tech, including a banjo-type air fitting and bolt that is machined from aluminum and comes complete with an 10mm hose barb for a fast response. There is also a high-temp silicone Nomex-reinforced diaphragm for a longer shelf life. This really is an impressive turbo blow off valve and one that is durable and easy to fit. It comes complete with all the fittings. When put to the test, the sound is stunning and is certainly not budget priced.


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