Atmo Bov

[Chris_Beli]

Hey guys would just like someone to confirm for me, I have a atmosphere venting bov, from what I've read up on it the screw on top of the bov adjusts how firm the valve spring is, the tighter it is the harder for air to vent, when boost isn't high enough air vents through the turbo which creates the fluttering sound which isn't good for your turbos life, when boost is higher it vents from bov and u get normal ppsshh sound, so looser screw equals less flutter and better for turbo, tighter equals more flutter, also I seem to get boost restricted with screw done tighter? Does this mean it is over tightened? Thanks for any help, I realise there are threads on similiar topics but everyone always talks about these things as if u already know what they are talking about so for a noob it's hard to follow....

[Bronx]

i had my blitz one on for a while till it just annoyed the living crap out of me. but besides that, take off your air filter top and the air filter, bolt on your BOV etc, then turn your car on, rev your med-high, then just let go, if you hear a psssshhhh, then your BOV is working, if you hear a flutter your screw is too tight, loosen your screw.

if it is still psssshing, tighten your screw just before you hear a flutter. then you have max boost your turbo is set to (factory 7 or 8psi). if you loosen your screw too loose, then you will loose boost, the lower your screw the easier it looses psi, it will let off at 4psi instead of 7psi, so kind of a giant power loss

[SMOKEYV35]

tighten the screw = more flutter

loosen = more psssh

think of it like a water tap - tighten it and it lets less water out, tighten it all the way it lets no water out. think of water as the air inside your intake, and you're on the right track.

having it tightened all the way up won't restrict your max boost - only your spool time between gear changes. the only risk to boost with a BOV is having it too loose, which can result in boost leaking past the valve.

is it truly a vent to atmoshpere BOV? or is it plumbed back into the air intake? if it really is a true atmo BOV then my advice would be to run it pretty tight - having it open up all the time will result in getting bad air/fuel mixtures as it dumps metered air out and causes overfuelling - which will just hurt your hip pocoket. it will make it flutter a bit more, yes, but don't buy into what everyone tells you about it hurting the compressor - VL turbo's dose all day long on 20+yr old bush bearing turbos and have no issues.

if you want to increase your performance, and your engine's efficiency - get that baby plumbed back or put the stock unit back on. it will be quieter, legal by the EPA, and your car will go harder.

[Chris_Beli]

Thanks guys, it's definitely atmo, stock one is still

on the car just blocked off so if I have a run in with the boys in blue it's easy to reverse to clear a defect, so far since it went in I haven't noticed any loss in economy but I guess my car has been overfueling since I got it anyway, and I should have mentioned it's not running stock boost, it normally runs around 11psi but I swear when the screw was really tight it was maxing out at 9-10 psi, maybe I was imagining it, as it is ATM I get flutter up to about 7 psi then ppsshh above that

[wolverine]

the only risk to boost with a BOV is having it too loose, which can result in boost leaking past the valve.

How does the boost leak past the valve when there is an equalising pressure from the plenum acting on the top of the valve? As long as the spring is physically holding the valve shut when the engine is off then it will only crack when the pressure in the intake is greater than the tension on the spring.

if you want to increase your performance, and your engine's efficiency - get that baby plumbed back or put the stock unit back on. it will be quieter, legal by the EPA, and your car will go harder.

I couldn't agree more. Get rid of the aftermarket BOV. There is nothing to be gained by using it.

[Bronx]

only replace your old one when you want more boost, your old one is set to dump at 7psi i guess, so even if your turbo is set to 11psi at the wastegate, those 11psi wont even get to your engieon cause your BOV wont let it go beyond 7psi.

get a nice adjustable plumb back one

i do still think that surging is bad on the turbo though, spinning freely at a couple thousand rpm to the right and then all of a sudden a stop and turn other direction will put strain on your ball bearing/journal bearings

besides your atmo giving you shit fuel economy and missfiring, your car will hit boost slower between shifts since its wasting that extra amount of air your ecu already accounted putting petrol in for.

[QWK32]

only replace your old one when you want more boost, your old one is set to dump at 7psi i guess, so even if your turbo is set to 11psi at the wastegate, those 11psi wont even get to your engieon cause your BOV wont let it go beyond 7psi.

Ignore this, the stock bov does not release air pressure above 7psi, if you run 11psi the engine see's 11psi.

The only issue with the stock bov is that it's getting old, I had mine let go at 14-15psi where as others have no problems holding 18psi. What Wolverine said is correct, on a bov in perfect working order the equal pressure will hold it shut. The stock bov is old, the seals are worn/shrunken/deteriorating and may pass air causing the bov to release under load.

In the end run whatever setup you want, atmo bov isn't that big of a deal if you can put up with occasional stalling, and pops and black smoke out the exhaust when backing off. IMO fuel economy is hardly effected dispite what some people will try and argue.

And again IMO a little reversion (flutter) isn't a big deal either, It won't effecting the stock turbo's response to a point where it's noticeable. And to anyone who says it will damage to turbo and Nissan put a bov there for a reason, the RB20 out of the cefiro does not run a bov at all.

Edited March 17, 2011 by QWK32

[Chris_Beli]

Thanks for all the opinions fellas, loss of economy does not concern me as like I said my car has run rich from day one, I get back fires when backing off full acceleration before the atmo bov went in, currently saving for a nistune and turbo rebuild to sort it all out, oh and the new bov does hold boost better then my stock one did