My $50 ebay BOV showed up today. Looks pretty good from what I can tell. I paid the extra $10 for a "piston type" BOV vs "Diaphram Type".

Of course, it shows up without any sort of instructions. So I've got a couple of questions:

- I forced the BOV to open by just pushing the piston with my finger. I was surprised at how much effort it took to open it... is this normal?

- I believe I'm supposed to hook up the vacum line to a manifold vacum source (after throttle body). Just wanted to double check if thats right?

- Also.. if I use manifold vacum to open the BOV, then the BOV will be open during regular crusing. If thats the case, doesnt this mean that It will allow un-filtered air into the system. Could this be a problem?

Thanks!

 

when you slam the throttle shut the engine returns to vaccum and pressure in the cold side builds. with the vac pulling and the pressure in the pipe the valve opens and releases excess boost. when the spring has enough force to overcome the air coming out it closes again. thats the simplest answer

 

Thanks, although I don't think you answered any of my questions other than perhaps verifying that the vacum line should be connected to a manifold vacum source.

Is it normal for it to take so much effort to manually push open the BOV? I was expecting something that could be pushed open with a finger. I have to use both thumbs to do it.

Do I need to worry about the BOV letting unfiltered air into the engine, or should it only open with the combination of boost pressure and manifold vacum? Will the BOV close once the boost pressure has been bled off, or is the manifold vacum enough to keep it open?

 

My Ebay BOV was hard to push open with my finger, but held fine up to 20 psi (well that's what I adjusted it to).

I don't know if it leaks at all or not at any pressure below that as I applied the pressure to one of the ports.

I've read before that someone put a filter on the outlet of the BOV to keep it from sucking in dirt and what not. Here's the link.
http://www.thedodgegarage.com/turbo_bov_mod.html

Also here's how I hooked up my BOV.
http://herpetology.com/dsm/bov.html


FWIW I have no filter on mine. I'll also probably replace my Ebay BOV one day as I wasn't too happy with the quality of it (the fittings broke easily) and as I mentioned I'm not sure if it leaks or not. It was an impulse buy when I bought it and I thought I was getting the real thing, but didn't. So far it works though.

 

Piston stye BOV's typically have an internal spring which is rated to your engines vacuum. Different idle vacuum requires different springs to ensure it stays shut at idle, yet opens quickly and effectively after getting out of boost.

Here is what I did to my tial style BOV. I started off by hooking up the BOV to an engine vacuum source. With the engine started and idling, I felt the tension of the piston. You'll want it to maintain closed, yet be very easy to push in at idle. If it's still to stiff, take it off and cut a little bit off of the coil spring inside the BOV and re-assemble. Re-check and keep adjusting as necessary.

 

Thanks guys.

With my cam, I have crappy vacum at idle. I'll have to play with it on the bench to see what I find.