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std BOV venting atmo, hypothetical question?

mattysaidso

By mattysaidso,
in Engines & Forced Induction

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mattysaidso Experienced

mattysaidso

Posted
Posted

heya,

i was jus in the process of re-fitting my std BOV to my R33 GTST. looking at the design and function of the std BOV i found myself pondering this question....

as a cheap alternative to buying a aftermarket BOV for that fulli sick thorpey style 'phhhhsssst' sound, would you be able to successfully use your std BOV?

now if you turn the BOV around the other way on the mounting point (yes it bolts the other way, i checked) so that the plumback piece is now pointing upward. and use a slightly longer piece of hose and reconnect the vacume line to it. then block off the pipe that returns to the inlet of the turbo. would the std BOV still function correctly, except instead of venting back into the intake, it would vent atmo instead?

now if this is possible and it works, how come very few, if any skyline (or other vechiles with the same std BOV setup) owners dont use this idea instead of parting with $300 odd dollars for a *brand* BOV?

the other thing i was wondering was maybe the std BOV makes a shit sound when vented atmo and that is why no one does this modification? when i get my cooler pipes back on i might turn the std BOV around jus to see what sort of sound it makes and how/if it works....

feel free to correct or answer any of the above questions or theorys...

cheers!

JCMarshall_Law Proficient

JCMarshall_Law

Posted
Posted

It will work, just try it, you will get that "fully sick" sound, it will also run like shite, bogging down between gears and backfiring like a biatch,

Stock BOV's leak at idle, so it will prolly idle like poo.

Personally I'd rather have my car running properly. Just get a pod filter and that should be loud enough for you and anyone standing nearby.

Oosh Veteran

Oosh

Posted
Posted

Even stock GTR items leak slighty, RowdyR32 had his venting to atmo on his RB26 GTST and it idled like shit, he added some ducted vacuum sockets (which seal under vacuum) and the idle improved greatly but they still leaked under boost.

Looked kinda cool tho with his vacuum flaps snapping open and shut when the BOV vented! :) It was a good experiment but not something you'd do long term, he's now got his own plumb-back piping and it runs a lot better all round.

mattysaidso Experienced

mattysaidso

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It will work, just try it, you will get that "fully sick" sound, it will also run like shite, bogging down between gears and backfiring like a biatch,  

Stock BOV's leak at idle, so it will prolly idle like poo.

Personally I'd rather have my car running properly. Just get a pod filter and that should be loud enough for you and anyone standing nearby.

yeah but if you plug the small hole inside the std BOV, then doesnt that stop the boost leak at idle?

JCMarshall_Law Proficient

JCMarshall_Law

Posted
Posted

That may help

but..

It is possible that the stock BOV will still leak at idle at there is quite a low pressure in the plenum at idle which causes the BOV to open slightly. Soon at you open the throtle, the pressure in the plenum rises and the BOV closes, no problem when the leak is plumed back after the air flow meter.

Someone with more experence may be able to confirm / correct this.

rev210 Grand Master

rev210

Posted
Posted

A couple of things...

Boost leak at idle?

You have to get past the whole 'leak' term it's actually a metered air bleed. It's not an accident it's a design and it's a good one. It does not cause boost fluctuations or prevent holding boost. Nothing is 'lost' it all gets put into the motor one way or another.

As for venting to atmo.

It isn't something that can be done easily. Blocking the small hole is only part of the issue, you then have to re-spring the valve is my guess (ideal is an adjustment screw for the spring tension to get it right) plus you will need to have a s-afc or something to deal with the ecu compensation for the recirculated air it's not getting.

Buy an aftermarket one if you must have the sound. As someone mentioned even the addtion of a pod filter will increase this noise a great deal.

But, if you like to muck around I say go for it. You can learn things that way too.

Oosh Veteran

Oosh

Posted
Posted

You're pretty much on the money, the spring tension in aftermarket atmo items is usually much higher than stock plumbbacks, a slight leak when you plumb back doesn't matter so its not seen as a problem.

If you get a bigger spring it should help, Nigel from ICE has 2 x GTR BOVs vented to air on his Supra, not sure if he did this (or maybe his dont leak) you'd have to ask him about it.

JCMarshall_Law Proficient

JCMarshall_Law

Posted
Posted
low pressure in the plenum at idle which causes the BOV to open slightly. Soon at you open the throtle, the pressure in the plenum rises and the BOV closes, no problem when the leak is plumed back after the air flow meter

I never said "boost" leak at idle, I just said "leak" at idle, and I did not say 'leak" was a bad thing (see above). Just that if you say the word "leak" enough times it becomes a rude word. Maybe I should have said "air bleed". Meh...

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