fluttering noise

[Drunkenmonkey]

Hey Guys/Girls

just a quick question, other morning heading to work instead of my bov realeasing pressure i got a fluttering noise which sounded WAY better!! poped bonned and the vac line came off my BOV, what is making this fluttering noise and could it damage the engine??

cheers guys

[Koom]

Thats the sound of compressor surge due to the BOV not opening.

It could possibly cause damage to the turbo, but there's a few different schools of thought on that subject.

[Disruptz]

It's deff not good... Your compressor wheel is spinning at like 100000+rpm somthing outrageous like that, the flutter noise you hear is the forced air being sent back through the turbo instead of being vented like you bov, i immagine.

When you think about it,, all that air being pushed back with enough force to spin the wheel which is travelling at 10000+ Rpm backwards,.. what good would that be doing?

[off2harrys]

my bov makes this stupid noise does it matter if it only happens at low revs

[Disruptz]

 off2harrys said:

my bov makes this stupid noise does it matter if it only happens at low revs

That's because there's not enough pressure being made to open the valve in the bov so it stays shut. To get rid of it you most likely need to adjust the spring rate in your bov. Or maybe in the odd case a loose vacume hose...More often the low pressure.

It's not as bad at low revs, but still not a good thing.

[Drunkenmonkey]

that makes sence cheers mate

[UnitedWeFall]

From what i've been told by different people/mechanics, the fluttering isn't always a bad thing. The BOV on my old car fluttered all the time and it never did any damage.

But yes adjust the spring rate on the BOV to soft and see if it makes a difference.

[pl0x]

is my car doing the same thing? even tho you can see the bov open the noise comes out the pod? at low revs only

[wildturkey]

mmmmmm.......this thread has me thinking about the noise my bov makes. when it releases ......whether its low or high revs .......it's not just 1 whoooooooshh! but more like a stuttered fluttering release. I've often heard the noise described as "butterfly". Are some bovs purposely made to release this way or should it just not be fluttering at all?

[Drunkenmonkey]

mines a hks knock off and its a one straight woosh i think its different to dif brands, i get the flutter wen i changes betweeen both turbos and with half gas to..

 pl0x said:

is my car doing the same thing? even tho you can see the bov open the noise comes out the pod? at low revs only

if you see it open and can feel air coming out should be all good means its not back feeding to the compressor

[Swindog]

Mine does the same thing. People are right on the train of thought. It also does it when the turbos NOT on boost so i think its a pressure release back through the system. Never had any ill effects but adjust your BOV to suit. If you look through you BOV instructions it will tell you to "tune" the bov to suit your system.

You HAVE to adjust it to suit your turbo weather it be hard or soft spring rates. This will eleminate most of the fluttering noise but not all of it.

[Guest]

i want a BOV tht makes the whistle (like in rally cars)

[UnitedWeFall]

 daleson said:

i want a BOV tht makes the whistle (like in rally cars)

You can get a "whistle" trumpet attachment for GFB blow off valves.. they only work above 12psi or something though.

[Disruptz]

 daleson said:

i want a BOV tht makes the whistle (like in rally cars)

I think that whistle sound is due to there recirculated bov's, or bpv, like your factory bov whic they run at like 30-40psi*... Or the other simmilar chirp sound is actually there brakes.