Todd/A.W.E.

<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/Boschdia.jpg"></center><p>Here is a picture of a diverter valve diaphragm from an Audi S4 BiTurbo. The valve would not hold vacuum, and a dissection revealed the typical way in which these type valves fail.

The outer lip of this diaphragm is the pivot point when the valve is opening and closing. Over time, this area of the diaphragm deteriorates and begins to split, until there is a complete breach. Any small tear here will not allow the valve to operate under vacuum, and will also allow boost to bleed past the diaphragm from the upper chamber.

This common failure is why Bailey Motorsports developed a better solution.

Bailey valves are in stock, ready for shipping!<ul><li><a href="http://www.awe-tuning.com/baileyvalve.cfm">Bailey Valves</a></li></ul>

Kevin K2

Nice valve, but don't think Baily invented the piston type BPV, as noted at your site.

Had an 81 924 turbo, with KKK-26 turbo that had an alum piston BPV built into the compressor housing. Signal/control pressure was piped from the intake manifold.