Zenki wrote:
This photo show how I pressure test the BOV (or dump valve)
https://www.facebook.com/photo.php?fbid ... =960%2C540
The direction of the dump valve will seal better if you put it in reverse. Actually, the flow direction in your photo will not seal properly.
I did many pressure test on these dump valve, included the plastic one from Bosch,
viewtopic.php?f=12&t=2545
This is exactly how I describe the bosch DV to someone :
I have test many BOV, Blitz, HKS, Greddy, RB20/25 stock bov...etc, all piston facing to the pressure side and the piston opening movement same as air release direction,
most of them leaking, leaking from the adjustable screw, leaking from the piston sealing surface, or the mounting surface. especially when over 1.5 bar. Can't hold the pressure, testing was done on a both end sealed intercooler pipe at 1 to 2 bar fully submerged.
And yes, high pressure acting on the back of the piston, this is exactlly the same as plastic bosch dump valve on Audi and VW, and the boost pressure help sealing the piston, more boost pressure , more sealing force, and it still works fine to blow off at high boost.
And this is the only BOV that have zero bubble when testing under the water, ( a good genuine HKS SQV still have zero bubble in the water but it blow off when positive pressure is droping, still positive pressure but not vaccume, I have also see an old genuine HKS SQV leaking seriously on all small bolts surrounding the valve body)
You won't belief, a small plastic bosch dump valve can hold pressure tight at 2.5 bar, when high pressure acting on the back of the piston, but it still leak when high pressure acting on the front of the piston.
