[s-cars] Forge BPV's ??(diverter valves)

[Kirby Smith]

Although my Forge installation does not include a long hose loop like
the original BPV configuration, possible reasons for the loop include
cooler air at the valve (but not by much), and dampened diaphram valve
flutter.

kirby

CaptMagu at aol.com wrote:
>
> Joern and Mike
>
> This was originally posted to the kremmer list but I thought some of you
> would enjoy this too.
>
> Joern, get rid of that Bosch unit before something gets sucked into your
> turbo. First things first.
>
> On the charge air line running from the turbo to the I/C we have a 28mm bib
> plumbed to a section of 63mm aluminum pipe. The BPV is plumbed between this
> charge air pipe and the turbo inlet. Additionally there is a vacuum line bib
> at the top of the valve that is pressurized from the intake manifold. As the
> biturbo list diverter valve test and article reveals the piston type valves
> can be plumbed either of 2 ways. We had them plumbed conventionally with the
> charge air pressure line feeding into the bottom of the valve against the
> spring. The problem here is that in high flow(make that Happersized turbos)
> you get too high a pressure differential. The boost pressure within the
> charge air line pushes against the piston/spring and intake manifold pressure
> from the top to prematurely open the BPV. This pressure differential exists
> because we are approaching if not exceeding the throttle body and intake
> manifold's ability to handle flow.
>
> This wasn't that much of a problem for me before that Mike Pederson talked me
> into cleaning up my intake tract with the Pederhousen Big MAF and the fluting
> to my I/C. Since the cleanup, I now flow significantly more air and thence
> the problem with the throttle body/intake manifold. We've got all this air,
> we just can't get it all to the very clean head.
>
> I have recently talked to the techs at TurboXS and they did indeed state that
> for big hp applications they now recommend plumbing the valve backwards or
> sideways. The charge air line is now plumbed into the side of the valve. The
> TurboXS valve does have a split piston with a shaft inbetween. With the
> charge air coming in the side it pushes against one side and the other. This
> nullifies the effect of the pressurized charge air. When you shift and go to
> vacuum, the top of the piston is pulled up, activating the valve and divert
> ing the air to the turbo inlet.
>
> Finally, one last thing. On the stock urS-cars the turbo to crossover pipe
> hose has the plumbing for the BPV. It comes off the curious snake hose affair
> on its way to the MAF to turbo inlet hose. Why did Audi plumb this loop in
> there? A lot of other applications also have a similar extra hose plumbing.
> Curious. That's all I know about BPVs, honest.
>
> Hap, no longer prematurly bypassing in Evergreen, Maguire
>
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