BPV install - is this right?

[DrD123]

Installed a turbosmart Kompact diverter valve that I have had on my shelf for a while - the turbosmart instruction seems incorrect - for their valve, they show the face of the piston against boost pressure, which seems correct - however, the drawing they have of the OEM diverter valve orientation seems wrong - boost should be pushing against the face of the piston (that is the inlet that installs onto the charge pipe coming up from the turbo) and the other end should face down to the pipe leading to the turbo (where the boost control solenoid, etc. is in) - correct?

[FLlegacy]

Installed a turbosmart Kompact diverter valve that I have had on my shelf for a while - the turbosmart instruction seems incorrect - for their valve, they show the face of the piston against boost pressure, which seems correct - however, the drawing they have of the OEM diverter valve orientation seems wrong - boost should be pushing against the face of the piston (that is the inlet that installs onto the charge pipe coming up from the turbo) and the other end should face down to the pipe leading to the turbo (where the boost control solenoid, etc. is in) - correct?

Funny enough my factory bpv was backwards for a time, I noticed no difference. I installed the kompact bpv in the same orientation as OEM though. And no issues with it.

 

If it faces the other way the boost cant physically push the valve open, iirc.

 

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[DrD123]

I would think installing it backwards would mean it couldn't vent period (since you'd have boost+spring pressure holding the piston closed) - everything I have seen shows the piston face facing the pressurized region, and the backside facing the intake - that's consistent with how TurboSmart shows their valve above, and that's how all the install vids I have looked at for the 15+ WRX have it set up. The only image I think that's wrong is how turbosmart drew the OEM diverter valve - they have it exhausting through the piston.

 

If the BOV can't vent, that just slows how fast pressure would drop (the engine is still sucking plenty of air - once the wastegate opens on the turbo, you'd stop building positive pressure and it should bleed right off) so the pressure rise from closing the throttle/backing off the gas could cause compressor surge - I imagine it's not that big a deal until the boost level gets really high, though...

 

I have though it's odd that Subaru moved the diverter valve so far from the throttle body - in the EJ20T engine it was right on the intercooler - now it's way down near the turbo...

[dgoodhue]

I mounted my Turbosmart BPV in the same orientation as stock. The stock BPV has the vacuum line on the left (passenger side), which is not how it is shown in the picture.

[DrD123]

That's exactly what I did, as well (in my first post, the second picture is the stock BPV which I removed from my car this morning) - their picture is more generic and just shows the single port on the top (I think that's how it looks on the WRX) - ours comes off of there, too, but is angled upwards. With the Turbosmart, it mounts exactly like that.

 

 

I was just remarking on the Turbosmart picture in their instructions, which shows boost going into the wrong port - so if you interpreted their instructions at face value, you'd install it wrong! This is the manual I was looking at

https://www.turbosmart.com/wp-content/uploads/2011/11/Kompact_PlumBack.pdf

[cww516]

If it's in there backward, it'll still vent. The boost side of the valve will be more or less pressure-balanced, you won't have too much in the way of vacuum pulling on the turbo inlet side, and you'll have manifold vacuum pulling on the signal side of the diaphragm.