Blow off valve nipple???????

[Elanlover]

The BOV-H I have installed isn't defective as far as I know. If you open them up there's really not much to go wrong with them other than the spring. Inserting washers compresses the spring making it harder for the vacuum forces to trigger a release. Vacuum force has nothing to do with air intake pressure - directly.

When you are under full throttle and take you foot off the gas the airflow reduces significantly and will cause back pressure which works to suddenly stop the turbo from spinning. When triggered, the BOV releases pressure in the intake plenum so there is no back pressure. The result is most noticeable not in an increase in turbo response whe you step on the ghas again (although that will happen) but in the speed in which you'll see the boost gauge needle drop between shifts. Without the BOV the gauge seems to drop to 0 instantaneously. With a BOV the drop is noticeably slower indicating that the turbo's still spinning and hasn't stalled. So, you described the BOV purpose better than I did

But, adding washers doesn't mean it opens under HIGHER air pressure (actually, it does but I'll explain that later). It means it opens only when higher vacuum is detected which is LOWER pressure through the connecting hose to the nipple at the top of the BOV. With all 6 washers installed I am getting the BOV to trigger as it should although 5 or 4 might still work too.

Now, think of how the BOV is installed. The botom of it is connected to the air route from the throttle body to the intercooler. Lots of air pressure there especially when the turbo's doing its job. But, the pressure pushes on the BOTTOM of the valve. That can also trigger the BOV. The BOV will open if there's vacuum at the top (nipple) OR higher pressure at the bottom of it. So, adding washers ALSO ensures that you'll need more pressure in the intake (turbo on) before it can get the valve to open by pushing it from the bottom (instead of a vacuum pulling it from the top). See what I mean???

The fact that you have a MBC will probably impact this but hopefully not much if at all. If you're running at max .92 bar (which is what the stock car will do before the fuel cuts out) then that means more pressure is being applied to the bottom of the valve which could cause "premature trigger eject-ulation" (weak attempt at humour) if the spring isn't compressed enough to hold the valve down.

My BOV operated perfectly with no washers at idle when installed. Stepped on the gas and it started to leak air when full boost was on. Install wahsers and problem goes away. Turbo XS didn't quesiton the number of washers installed. They did say that 0 washers was an unlikely situaiton but, every car is a little bit different regardless of the similar specs. I could probably drop a washer or 2 but I'll play around with that later (or probably just install the recirculating BOV). But, its very possible that the springs are different. They are not all the same and 2 springs made identically are not likely to have the same characteristics. This could explain the differences between our setups.....and the fact that Turbo XS supplies them with so many washers and doesn't just do one setup for all.

Bottom line is that if its giving you the performance you want without damaging the car in any way then yes, don't fix it (although one of ESM's chips would be a better solution than an MBC ).

[Monty]

BOV will not really effect the car at idle, IMO the washer is a form off adjustment, so when adding the washers u'r shortening the spring which makes it more stiff then the piston comes more harder to open so doesn't release the pressure to early.

I'd find it hard to believe that you'd get the BOV activating at idle causing roughness. You'd have to have a lot of pressure in the intake to do that. I certainly didn't have that at all. With boost on though you can get the valve releasing if the spring isn't tight enough causing you to have a reduction in max boost as air leaks through the BOV.

Who said that BOV is activated at idle?

I just that the BOV does not effect idle, u can even remove the top intake pipe and the engine still ticks over as normal.
If the spring isn`t tight enough u know if u were losing boost, u should be hearing the wossh sound when coming of the gas or changing gear. Your making the far more complicated than it is. Its a very simple system.

[Elanlover]

Uhhmmmm..........Monty, I think that's what I was saying. Agreeing with you. The BOV should not trigger at idle (which would cause rough idling) unless the spring isn't compressed enough and "normal" pressure in the intake is causing it to release.

So, yes, The BOV should not impact idle unless its installed improperly or has a really weak spring. And, you can hear 2 distinct "whooshes" by the way. The sound of the vacuum activated whoosh is different from the intake pressure activated whoosh. I've heard both (before I installed the vacuum hose to the nipple )