I took my BOV off today cause I was sure it was leaking, and you wouldn't believe what I found out...

The factory BOV is designed to leak !!!!

Yepp, it's designed to leak....

Have a look at the attached pic. If you blow into the return pipe (big pipe on the bottom lefthand side) it will blow through the BOV and out that little hole on the front. That means there is always a path to recuiculate a small amount of air even when the BOV is totally shut !!!

I don't know why....

Anyway, here is a quick "how too".

I got this idea from a bloke on SDU. The link is here http://forums.skylinesdownunder.co.nz/show...=&postid=191358

J

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I found a wood screw that had a flat head that was about 1 1/2 inches long. It'll be hard to find one that fits good, but keep looking.

The important thing to do is to counter sink the hole a little in the BOV so when you screw the screw in it sits flat with the base of the BOV.

You can see it in this pic.

Then you put the screw in the hole (!!!) and tighten up.

Not too tight cause it's into aluminium, but it must be flat with the base of the BOV.

Put it back on the car and your all finished.

The car does feel more responsive when on boost. And there isn't that sound of recirculating air when your on boost as much.

The sound it makes has changed slightly. Before it was more of a ssssssshhhhhhhtttttt noise. But now is more of a pppppssssshhttt noise (if that makes sense !!).

It sound like it's holding the boost until you come off the throttle instead of passing air (LMAO :lol: ) when your foot is still down.

It can't be bad for it, have a look at any of the after market BOV and they don't have this little bleed hole, so what the hell

Have fun.

J

what a great discover!! champ!!

Should probably put some loctite on the screw too, dont want it shaking loose!

would that damage something? later?

surely the hole is there for reason...

cheers
Joe

th hole is ther to recirculate a little air when off boost

its supposed to keep the turbo spinning faster so it spools up quicker


but if you want to block it all you need to do is put a thick peice of gasket paper over the hole and when you clamp the bov back down again it will be held in place and thats enought to block it properly

no screws required

Cool, good to see there's some sort of reason why it's there. It's a shame that sometime effects it pretty bad when running higher boost

Joe - that screw won't go anywhere, when you bolt the BOV back on it's hard up against the crossover pipe mounting point. No way it's coming out

I blocked mine with a nail and the head covering the hole last nite....the noise is different as noted, but apart from that didn't really notice much else....

What's every1 else noticed?

I've been keeping an eye on the boost gauge today.

With lite throttle boost situations it seems to come on faster. Before if I was accelerating slowing and it gradually came on boost I found it would get to about 1-2psi, then drop back to 0 and then build up again. Not sure why, but that has now stopped.

I figure that hole would bleed at least 2-3psi of boost. I think the hole is a great idea if your running standard boost, but if you up the boost it'll bleed more.

I'll be leaving mine with it in. Can't hurt, plus the noise is fulsik now.... maaaateee... :lol: :lol:

some got a g-tech or something to measure th effect propperly?

Well it looks like someone else came up with the same idea a while ago!!

Have a look here;

http://www.thedodgegarage.com/turbo_bov_mod.html

But they did it slightly different so you could have it "fast open - like stock" or normal so it hold boost better.

Rev, I can't confirm any times or anything, and I'm not going to guess, but to me it feels more positive. Either way it's easy to reverse if need it be. OH, BTW - I did the thermo fan install yesterday. It does rev slightly faster now, nothing amazing, but there is a difference. It's so quiet now too, but when the fan turns on it sounds like a jet engine !!! I now like your idea about reducing rotational masses. :uh-huh:

J

I noticed that extra port doesn't actually go into the plumb back section of the BOV, it has it's own tunnel into the diaphram part, how does it circulate air?

I put mine back to stock tonight, and it fells better on both 8psi and 1 bar...more responsive for me....though i miss the sound

Hi, that was my original post on sdu
the boost doesn't actually leak thru that hole, when enough pressure goes throught that hole it opens the bov piston. and the boost escapes through there.
it is just a system nissan has put there to prevent overboosting

If you've got the BOV sitting in your hand and you blow into the plumbback pipe, air will come out that small port, regardless if the valve is open or closed.