Blow Off Valve soundclips!

[JNS Performance]

Best, nuff said! Greddy Type-R

Rather extreme, he has it set loose for his setup.

http://www.youtube.com/watch?v=P4Xdmk7qsGo

Car I imported last year.

http://www.youtube.com/watch?v=VbiT8stjtFc

[Wrath]

Stock BOV can do that flutter sound when modified (my car does this). But the flutter sound is a form of compressor surge (air hitting compressor blade and slowing compressor wheel down) that's not good for turbo CHRA (Centre Housing Rotating Assembly). A BOV is meant to remove compressor surge and keep the turbo spooled. It's function, not sound.

So is there no way to get that lovely sounding flutter without compressor surge? I find this hard to believe.

[91rsrskyline]

So is there no way to get that lovely sounding flutter without compressor surge? I find this hard to believe.

the flutter IS compressor surge, you hear it in those videos because the bov's are set to open at a higher psi, so with the lower psi shifts or revs, the pressure goes backwards through the turbo making it stutter.
not really good for it.

my factory recirc works and sounds pretty good after extensively compressing it, no leaks though.

[hks_gtr]

I'm not running a BOV and i'm running 25psi......... just don't be cheap and the whole you HAVE TO RUN A BOV OR SH*T BREAKS theory dosn't apply to you

[billboa]

the flutter IS compressor surge, you hear it in those videos because the bov's are set to open at a higher psi, so with the lower psi shifts or revs, the pressure goes backwards through the turbo making it stutter.
not really good for it.

my factory recirc works and sounds pretty good after extensively compressing it, no leaks though.

I ono man ive heard there is a difference between BOV flutter and compresser surge. They sound a lot a like but u will notice compressor surge sounds more like its ticking.

Ur telling me every car ive heard with flutter is experiencing compresser surge and is ruining their turbo? ur telling me every car with the HKS ssq(the old one) is ruining their turbo? Ive heard flutter on some insane cars(420 whp FC) in person and a lot better ones online and to get that much power u need to get a big expensive turbo and I can't see them doin that if it gonna **** it up.

[Skym]

Wrath, as far as I know the mod you do to stock BOV (block little hole next to main valve) removes the quick release function hence the fluttering sound (not venting air quick enough) at lower boost levels, lower load and proper release (psssh sound) at higher boost levels, higher load (going up a steep hill). You can get the quick release function back by running a boost feed to bottom of BOV, like in the Dodge stock BOV mod (same Mitsubishi BOV as used on Skylines) -

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

From what I can see most aftermarket BOV's don't have a boost feed. Only BOV that I've noticed that does (I think is port C) is Synchronic/Synapse BOV. I think the other BOV's on the market rely on size of valve, spring strength to get around the fluttering problem.

What I like about the Synchronic/Synapse BOV is that it's setup from factory to not leak or flutter (has quick release function like stock BOV), so no need to adjust / replace springs or buy a bigger valve. But it seems you can make Synchronic/Synapse BOV flutter by not connecting the vacuum, boost hoses to Synchronic/Synapse BOV properly or running to atmosphere with fitting that makes it flutter a little bit (I presume not venting enough air due to fitting).

This is a pressure test that pushes Synchronic/Synapse BOV to 37psi -

http://www.youtube.com/watch?v=jIjy-DennWU

You can there is no leaks up to 37psi and see how fast the Synchronic/Synapse BOV vents air on the computer screen at very low or high boost levels. That's what makes me interested in buying this BOV to replace the fluttering stock BOV on my car, because there is visual proof (can see for yourself) that it vents all air at any boost level under 37psi very quickly.

[Oakville]

4:54 and 5:12...sorry for bring FAF into this. but it is just instant tent-pitching

http://www.youtube.com/watch?v=ek3i2lNPLUc

what is this!!! :O

[Wrath]

Skym, I'll take your points into account but someone please tell me what this is then. I doubt Signal Auto would run this machine with compressor surge. I was told it could be external wastegates making that sound. There must be a way to get this flutter. I understand BOV's are for purpose and not sound but I love that sound and I want it on my car.

http://www.youtube.com/watch?v=nR0ebxVoKNo

[Skym]

The acceleration sound sounds like external wastegate, engine. That's the BOV or BOV's x2 on a GTR with the flutter sound when backing of throttle to change gear or slow down. Even the HKS R34GTR demo car does it. Flutter sounds cool, buts it's bad for turbo's over time. I gather tuners don't care, as they have the $$$ to replace turbo's.

This is a external wastegate sound during acceleration, BOV (BOV is the high pitch release sound when backing off throttle) going off on a RB20DET -

http://www.youtube.com/watch?v=-ByyRe3N01A

That's what it should sound like when working properly.

My car makes the same flutter noise with modified stock BOV at low boost levels.

[love_boost]

the bigger turbos are fine with no bov since the shafts are beefier, also some turbos come with antisurge housings so running no BOV dosent affext them from what i understand.