for those who use the bleeder valves to control boost/pre-control and eliminated the solenoids/ecu from the control loop and letting the bleeder valves vent to atmosphere.....

...upon vacumm (when not on boost)... isnt the bleeder valve allowing unfiltered air to pass into the intake, or do the the actuators only flow air one way, effectivly being a checkvalve.

 

hmm, seems i could solve this issue by tapping in two nipples into an intake pipe and run the vent of the bleeder valves into the intake pipe....

 

This same question was raised about the stock BOV when used without a filter(long time ago).

Even at idle the stock turbos are spinning and should apply a light pressure.

It is a most easy test to check if you really want to know for sure. JUST DO IT!

 

actually cewrx7r1, some of what you said is not correct:

first, the bov is a check valve by nature, so it will not draw in air, only vent, so it is not an issue with the bov

second, while the engine is in vacumm (ie idle), the turbos may be spinning but there is NO PRESSURE, it is sucking in from the air filter all the way to the engine, the turbos are spinning because air is being 'sucked' by them

just wanting to clarify what is happening here, thats all

 

I don't think BOV is check valve when I tested my stock BOV I applied vacuum to nipple and I can blow the air to both ways.

and even engine is Idle my BOV blowing air out that means there is a little pressure.
you can test it by disconnecting hose..

 

sorry, i ment the bov acted like a check valve in that it opens to release pressure and is not open when no vac is applied to it, not allowing air in.


.... i just dont understand how there can be pressure there and at the manifold it reads vacumm? (at idle)

in other words, at idle there is vac at the manifold (a lot, like 14~19 in), and that means there is vacumm from there al the way to the air filter, including the turbos....and not until you gas it enough for the exhaust to spin the turbos enough to overcome vac and move to pressure will you see pressure at the bov...am i wrong here?

 

The throttle is a restriction. Everything in the intake tract between the throttle and engine block can and will see negitive pressure. You only worry about vacuum leaks after the throttle. It's kinda simple, you worry about boost leaks in the parts of the intake track that see boost. You worry about vacuum leaks in the parts of the intake track that see vacuuum.

The lines that control the wastegate and prespool valves do not see vacuum.

 

ahhh, interesting...thanks for the clarification

 

yeah what creates the vaccum is the throttle body. when it is closed, the engine sucks air instead of taking the boosted one from the turbos.

If you put your vaccum gauge before the throttle body (like on the intercooler) you should see 0 vaccum when the throttle body is closed.

 

ahh , ok i was wrong then...so the vented side of the bleed valves will never be 'sucking' in air, right?