Re:what to do about pcv valve from boost
 

I guess it's early or I'm just stupid, but where does the purple line hook to. I see it says the intake pipe pre turbo, does that mean you weld or tap in a fitting?

Re:what to do about pcv valve from boost
 

So guy, what happens when the pcv valve on the exhaust closes and there is no were for the vapors to go?? Also why would you sugest to keep the stock PCV system when it was not designed for boost? This can be VERRY BAD for your rings! :-\

Re:what to do about pcv valve from boost
 

And I've also seen a couple people run two lines from there valve cover on the front to the can itself. Any difference in this set up than the others.

Re:what to do about pcv valve from boost
 

^^^^^^^^^^
Valve cover is typically for breathing, sucking air in. I don't really know why a catch can would be connected to it?

Re:what to do about pcv valve from boost
 

my valve covers alway seem to putting out air rather than in.

breathing doesnt mean to take in air, now does it?

Re:what to do about pcv valve from boost
 

It *should* be sucking air in. On a v8 one side sucks, the other blows (valve covers that is). Are you running a turbo and is it hooked up properly?

Re:what to do about pcv valve from boost
 

Whats inside the catch can ? i guessed it was empty and made my own with an old rad overfill that i had laying around , would it work correctly ?

Re:what to do about pcv valve from boost
 

most catch cans are empty cylinders but some are filled with a foam type substance I believe.. I've never bothered to take apart a high end catch can to find out :-\

Re: what to do about pcv valve from boost
 

This thread shows 2 different setups, 1 setup with the breather element, the PCV is likely always working in the high vacuum range, means low PCV recirculation all the time. While in setup 2, PCV is always working in high circulation mode, or if you are unlucky, 0 vacuum leads to blocking PCV.

Basically, it works on the difference in vacuum between intake and intake manifold. Take a minute to understand that this difference is also how people measure load of the engine. Low vacuum difference = high load (WOT), high vacuum difference = low load (TB closed). Also note that under all conditions, vacuum pre TB is always higher than post TB, it is just a matter of high or low.

Now, physics tells us that when vacuum difference between intake and manifold is high, air will take alternative path through the crank case into the intake manifold. Without the PCV, during low load, high amount of air will take another route due to high vacuum, and vice versa. This is counter intuitive because we want maximum circulation during high load.

So, PCV valve is put in to "reverse" the bahavior, as below

if vacuum is -ve : Reverse flow situation, intake manifold has higher pressure than intake, PCV blocks. (this never happens in NA anyway)
if vacuum is 0 : Engine's off, or instances where both vacuum and intake manifold are of the same pressure. The PCV blocks.
if small vacuum : High load condition, maximum PCV bypass
if high vacuum : Low load condition, small PCV bypass
if very high vacuum : PCV blocks (condition of back fire, causing temporary pressurized crankcase, PCV blocks to prevent fire from reaching the intake manifold)

As you can see, on both end of the range of vacuum, PCV blocks, and it is best to design your system such that during low->high boost/throttle, the vacuum difference works in the range of slight vacuum to some high vacuum level.

Re: what to do about pcv valve from boost
 

wow, thanks for bringing up a dead thread :P