BOV flutter? Cooler Flutter?

[YBSLO4]

Hey all,

Wsa just thinking bout it the other day after i heard a VL with some crazy ass sounding BOV flutter was real loud, and was wondeirng why mine doesn't do it? I have a huge bar and plate cooler, big turbo, BOV, filter etc and i get flutter but not like other skylines i have heard...? I don't get that hollow sound or slow sounding flutter, mine is quick. SO i took my BOV off and went back to standard one to see if it was my BOV and now i got absolutely none... but i have heard heaps of other skylines with just a cooler and the stock BOV that flutter mad... just wondering why mine don't do it? Or if there is a BOV that has a better sounding noise... i.e. I heard the A`Pexi BOV makes this sound.

(P.s. please don't all right its compressor surge cos i kno it)

[PranK]

my old pulsar had the phattest flutter.. it had no BOV, it was just pressure running back past the turbo.

my GTR flutters a bit with the stock BOV's on.

[Guest RedLineGTR]

usally with pods your can hear the flutter. Have my stock bov on now...when i get between 2000-2800 i get flutter effect might just be the bov or something, but when over those rpms i get a proper sound pppssshh like sound cos of the pod and no stock airbox..i dont beleive the flutter at around 2000-2800 does any damage since there is a low amount of boost coming on, it could just be the bov since there is not enough pressure to open it up fully it opens abit at a time, not enough to fully keep it open. Hope it helps somewhat *shurgz*

[YBSLO4]

Yeah if i run no BOV i get flutter but thats jus compressor surge routing my turbine shaft and thrust bearing... so i'd rather not, but i heard skylines all the time with no aftermarket BOV that flutter awesome, so the only thing i could bring it down to was that its cos i have a bar and plate core as aposed to tube and fin... i dunno got me stumped.

[YBSLO4]

Yeah i have a filter also and yeah that does amplify the flutter sound as its coming directly off the turbo, and that is in fact where the sound comes from, but i jus can't work out why after those rev's also that it doesn't flutter... i think i might go for BOV number 4 and get an A`Pexi dual chamber and see, cos my mate has one of them and it flutters unreal, real slow distinct sound... and if it don't work then i'll chuck it out the window ont he freeway ha ha

[GaryD]

my leet setup with a turbofart plumb back that actually vents atmo makes long fluttering noises. its mad when youre just cruising but sounds shite on quick gear changes

[YBSLO4]

Yeah i had a Type 3 Supersonic on, it had huge flutter but it sounds like the BOV opening and closing continuously (the piston actually jitters if you watch it) but doesn't sound like the normal flutter. Sounds alright but not great. Pretty loud tho. I just went for a drive then with no BOV at all and it sounded sick, i just want it so stay like that without doing damage to the turbo. I know it can be done cos i heard it on heapsa other cars so i'm gunna find out how.

[TTT]

dude.

the skylines you hear making a fluttering with the stock bov means that the bovs are blocked of either under the bov or in the return pipe where you can't see it.

and so the sound you hear is just compressor surge as air goes back through the turbo.

VL Turbo's DON'T have bovs as standard and as soon as you put a pod filter on them, you can hear them fluttering away on gear changes or throttle off...

the sound all depends on the turbo blade and type of piping from the turbo to the filter..

if the turbo blades a more further apart, you will get like a slow flutter.. like ch ch ch ch ch

if the blade design is different, the flutter will be more of a ft t t t t t t...

you get me?

and the loudness of the sound depends on the piping from the turbo to the filter... because this is what makes it louder or quieter depending on the material it is made of..

like if it is the standard rubber item, it won't be as loud as if it were made from a LARGER diameter stainless steel pipe..

You will be dissapointed when you waste your money on the APEXI bov as the flutter sound will not change at all.

the bov should simply make a psshhh sound of some sort..

not a fluttering sound.

[YBSLO4]

Yeah know all bout the compressor surge and the piping differences as to pitch and sound of BOV, but then why do cars with say GReddy Type S/R or A`Pexi BOV still flutter... must be because the BOV spring is tight and hence not opening? I am running all alloy piping for cooler and am changing the pipe from the inlet of the turbo to the filter to alloy aswell once i get the computer in and can remove the plum back lines for the standard BOV. So if i change this to alloy it will amplify the sound eh? But obviously not as much as it is softer than steel which would resonate a lot more... stupid really that i am even bothering with all this but its a mad sound lol

Ads for changing from the Turbosmart BOV i have found that it doesn't go well with my turbo... not sure why but when i am on the throttle say in a constant gear (i.e. 5th gear on fwy) then i back off even the slightest to control speed the BOV piston starts fluttering and wont stop until i change my throttle position, so it is shit to drive... like i am talking ti can keep the BOV doing this for km's, its plain stupid and jerky to drive. So iunless i can cure thios i want a different BOV that will more suit my turbo, hence something based on say a pull type design like the HKS SSQ.

[AeroGrace]

i can hear flutter AND my BOV venting at the same time at lower revs....at higer rpms it vents alrite though...no flutter.

one of the bad points of the HKS SSQV is that you can't adjust the tension of the smaller valve, the screw only affects the larger valve...no matter how much you loosen the screw it won't affect the smaller valve's tension

[HRthirtyone]

yea my mates s15 sileighty had no flutter/very little flutter with stock BOV, when an adjustable racepro BOV was put on, any less than 5-6psi you can hear a prolonged FLUTTER LIKE CRAZY... but with higher boost it would do the normal BOV thing. I put this down to the harder spring setup.

[YBSLO4]

Yeah, the prolonged flutter i am talking about wont stop until i take my foot off the pedal. Its stupid... i have tried re-adjusting it and it makes no difference whether the srping is set hard or easy so i dunno. Gets annoying tho.

[HOTR33]

From what I understand (and I hope we're on the same wavelength) .... Running NO BOV, ie. replacing the stock/aftermarket one with a metal plate blocking the opening off, will cause all pressure to flow out tru the turbo, making the fluttering noise...

From what I understand running under about 14 psi, this is fairly safe to to on a street car, anything higher and the causees damage to your turbo.. Plus an advantage from this setup is that You can get a boost spike which throws the power down..

Ask R31Nismoid about his setup as he has an R31 GTS-R , and it runs no BOV from the factory, and he can explain a bit better...

But when ever I watch my HPI DVD's .. and Listen to the track cars over there, it sounds as tho they are not running a BOV from the flutter I hear after their burnout... which they may do to get that boost spike I meantioned.. BUT they run High boost AND replace turbo's often.. Hence the 14psi+ Rule in regards to damaging the turbo..

This is what I gather from talking to various people.. I may be wrong or mislead.. but it's just my 2 cents worth...

[TTT]

Well the way I see it, NISSAN put a CERTAIN bov on my car, believing it was required and good enough, and that is reason enough for me to leave it there.

I will not REMOVE or REPLACE with aftermarket.

[YBSLO4]

I found out recentyl that running an external wastegate has a large deal to do with the flutter. The flutter you would hear on your vid's from ripped jap cars is because the large majority of them run bigger turbos which need external wastegates and is the reason alot of them flutter on the burnout cos they are reving high enough for it to bypass gasses and flutter as the turbo constantyl produces pressure after each time it releases air... makes sense cos its running of exhaust gases. However i still can't manage to work out why mine sounds so different to other skylines out there... i think like someone mentioned earlier the fin shape on turbos has a lot to do with it, and as i have an after market bigger turbo then thats probably the reason, but i'll keep searching for the answer to end this discussion once and for all lol.

[GR33DY]

ok.. i had an afta market BOV (HKS), with cooler and standard air box.. i got no flutter what so ever.. Recently i bought a afta market pod, and the flutter is amazingly LOUDD! at 1500rpm u hear the flutter go.. im only rnning 7psi with all these mods.. is it bad for my turbo? I also have 3" exhaust from turbo back and a s-afc.. there has been so much talk about this topic that itts confusing me.. Flutter does sound way better.. btw, is there a way to check if ur standard BOV is blocked off, and this may seem really dumb, but where is the standard BOV located? lol

[wld808]

i once had a series 2 rx7 in which i put a series 5 turbo motor with a pod filter screwed directly onto the turbo and no BOV, i had the loudest flutter i ever heard in my life, i hated it so i changed the setup. btw i ran a 12.7 1/4 with a motor and a turbo that needed rebuilding.

[LowRollaBoy]

Recirc bovs also help reduce emissions, similar to your egr valve, an recirc bov constantly recircs your compressed air, as most oem ones open up even in vacuum.

Appart from that, theres plenty stock ca18det, e15t, rb30et, fj20t's still running about, and they dont have any oem bovs.