BPV Question

[EvilMSP]

Ok I know this is an idiot question that will only require one post to answer but I am lost on the BPV topic.

BPV = .......Blow Pressure Valve? Just a guess.

What exactly is it? What does it do? Why do some people want them and some don't? Sorry, just a little lost here.

[Dexter]

bypass valve

[boostisgood]

Bypass Valve, it lets the pressurized air to reenter the intake tract before the turbo, when you let off the throttle. It is so you dont have that air forced back to the tubo, because the throttle plate is closed.

Every MSP has one, some people want the BOV which is a Blow Off Valve. They, mostly, vent to the atmosphere. Those are the ones that give you the psssshhhhht sound, instead of the gobble type sound of a BPV :D

[Dexter]

the gobble is not caused by the BPV, for the 50912th time :rolleyes:

[EvilMSP]

Originally posted by boostisgood
Bypass Valve, it lets the pressurized air to reenter the intake tract before the turbo, when you let off the throttle. It is so you dont have that air forced back to the tubo, because the throttle plate is closed.

Every MSP has one, some people want the BOV which is a Blow Off Valve. They, mostly, vent to the atmosphere. Those are the ones that give you the psssshhhhht sound, instead of the gobble type sound of a BPV :D

Ahh thanks that makes a lot more sence. Is there a performance difference? Or just a sound difference? I would much rather have the pssssshhhhhht than TURKEY TIME!

[Striker187]

no performance difference. no sound difference really either. if you vent, you'll sound loud alright. if you recirculate, you'll sound almost as loud. like on a 1-10 scale, probably an 8 if you recirculate. the stock bpv is freakin loud once you put an open air filter on. and like dexter said, the bpv does not cause the gobble sound. many other tuned cars get this same sound...i'm not 100% sure if it is caused by the wastegate but it does seem like a likely suspect.

[EvilMSP]

Sounds good. So the new BPV that you get with most of these kits is "better." But all it really does is make the turbo a little softer than the stock one when you upgrade the intake.

Seems like I would go for the new new BPV because I've seen a video or two where the turbo was a little to loud to me. Thanks for the help everyone.

[KyRaceFan]

the "flutter" or "gobble" is compresser surge.

[Striker187]

but isn't compressor surge bad? you'd think that tuned cars wouldn't have compressor surge.....

[EvilMSP]

If it is flutter surge, is there a cure?

[MSP2NV]

get a new BOV or BPV that should put a halt to the compressor surge.

[jred321]

Originally posted by Striker187
i'm not 100% sure if it is caused by the wastegate but it does seem like a likely suspect.
how is the wastegate a likely suspect? i've asked this in 3 different threads and have never gotten a response. it makes no sense to me that the wastegate would cause this noise.

[rjspeed]

what company makes a BPV that a bolt on? Which is the loudest and best performing?
Is it ture you need hard pipes to run a BOV?
Thanx
Ryan

[MSP2NV]

Greddy makes a good blow off, and HKS makes the most efficient. Most people like the greddy type S cuz it sounds cool. and you don't NEED hard pipes, you just have to make sure it isn't leaking if you don't use them.

[Striker187]

jred - i say this b/c other people have said this. but i'm not 100% sure they are right. but i have seen clips of other tuned cars (turbo is300, supras, silvias), and they have this same flutter sound that we have. it's also been shown that simply replacing the bpv with an aftermarket one does not solve the turkey problem. i forget who it was that posted, but they used an hks ssqv but still got a turkey. hard pipes don't seem to cure it either. a wastegate would be common to all these cars so it makes sense that it could be this. but like i said, i'm not 100% sure.

rjspeed - all the bovs do what they're supposed to do, release pressure. so there's not exactly one bov that stands out from the rest. the only one that may be "better" than others is the hks ssqv because it utilizes a pull-type valve (meaning the pressure inside the pipes actually forces the valve closed). this means that the bov will not leak under boost. hks is the only one to use this design to my knowledge. others use a spring to force the valve closed while under boost.

the loudest is most likely the turbo xs rfl. this is supposed to be insanely loud. as they say, "if you need to ask, it's too loud for you." but hks, greddy, blitz, apexi, turbo xs, will all be loud.

no you don't need to hard pipes to run a bov. there's a company that makes a flange for both the hks ssqv and greddy type s that bolts on to the inlet of the bov. you can then run a 1" diameter hose to the flange. check it out at www.8vturbo.com check out ryan's sig, he has this setup. he's also got bigger pics floating around. you can probably do this with other bovs/bpv though you may need to have a custom flange made.

[jred321]

Originally posted by Striker187
jred - i say this b/c other people have said this. but i'm not 100% sure they are right. but i have seen clips of other tuned cars (turbo is300, supras, silvias), and they have this same flutter sound that we have. it's also been shown that simply replacing the bpv with an aftermarket one does not solve the turkey problem. i forget who it was that posted, but they used an hks ssqv but still got a turkey. hard pipes don't seem to cure it either. a wastegate would be common to all these cars so it makes sense that it could be this. but like i said, i'm not 100% sure.

but if you look at how a wastegate functions, the fact that it is on the wrong side of the turbo to be made louder with an intake (as everyone says it does), it just makes no sense that the wastegate would cause this. and i bet that on those other cars if you change to hard pipes you won't get the sound, yet the same wastegate is still there. i agree that it isn't the bpv itself, but i see no reason that it would be the wastegate.

[Striker187]

the other cars were running hard pipes. the two silvias i saw were the champ s14 and the kei office s15. both of these have that flutter sound. the turbo is300 i found right here on the boards, somebody posted it. though no clear shot of the engine bay is given, i think it's safe to say that he's running hard pipes. the supra i saw i believe was orido's personal supra. i'll have to dl the clip again to make sure.

but it's good we agree that it's not the bpv :D

[jred321]

Originally posted by Striker187
the other cars were running hard pipes. the two silvias i saw were the champ s14 and the kei office s15. both of these have that flutter sound. the turbo is300 i found right here on the boards, somebody posted it. though no clear shot of the engine bay is given, i think it's safe to say that he's running hard pipes. the supra i saw i believe was orido's personal supra. i'll have to dl the clip again to make sure.
odds are those cars, if highly modified, are running external gates

[rjspeed]

rjspeed - all the bovs do what they're supposed to do, release pressure. so there's not exactly one bov that stands out from the rest. the only one that may be "better" than others is the hks ssqv because it utilizes a pull-type valve (meaning the pressure inside the pipes actually forces the valve closed). this means that the bov will not leak under boost. hks is the only one to use this design to my knowledge. others use a spring to force the valve closed while under boost.

the loudest is most likely the turbo xs rfl. this is supposed to be insanely loud. as they say, "if you need to ask, it's too loud for you." but hks, greddy, blitz, apexi, turbo xs, will all be loud.

no you don't need to hard pipes to run a bov. there's a company that makes a flange for both the hks ssqv and greddy type s that bolts on to the inlet of the bov. you can then run a 1" diameter hose to the flange. check it out at www.8vturbo.com check out ryan's sig, he has this setup. he's also got bigger pics floating around. you can probably do this with other bovs/bpv though you may need to have a custom flange made.


Where can I have a custom flange made? I was going to order the RFL but I dont think its worth it now. I know a few people with this BOV and its worked very efficently for them. Which is louder HKS ssqv or Greedy Type S? I take it that there is no aftermarket BPV available? Is this correct?
Thanx agian for clearing this up and with all your help.
Ryan

[Striker187]

you'll probably have to do a little searching in your area. plus take a good look at the inlet of the bov and see how a flange might be made (something similar to the one made by 8vturbo). most likely, the hks ssqv is louder but the greddy type s is plenty loud. and plus it depends on where you place the bov. if you put it right next to the intercooler which is nearer to the outside (rather than close to the throttle body), it'll sound much much louder. and yes there are aftermarket bpvs available. turbo xs makes a few and there's a couple bovs that allow you to recirculate part of the air and vent the rest. sounds like a cool setup. but of course, you can also recirculate the hks ssqv and greddy type s effectively turning them into a bpv.

[rjspeed]

Striker
Thanx for all the help I really appreciate it as this is my first turbo car. Do you have any pics as where to mount the BOV so that it will be loud? Also what is the price difference between the two BOV's and where can I order them at?
Thanx again
Ryan

[KyRaceFan]

Originally posted by rjspeed

Which is louder HKS ssqv or Greedy Type S? I take it that there is no aftermarket BPV available?

HKS is louder... its a sharp whoosh
Greddy Type S is like a whistle.. go listen to the BOVs from F&F..thats a greddy BOV being used on most of the cars.

If you get hardpipes made,like the ones im getting done, then you just have them weld on the appropriate flange. The HKS type h rfl comes with the flanges ready for weld. HKS does too, but i think its extra

[YuYuRena]

Originally posted by KyRaceFan
the "flutter" or "gobble" is compresser surge.

I wouldn't say it's a compressor surge. Trust me, I have seen compressor surge on a larger "scale" and it's something that FAA doesn't like. Plus if it's a compressor surge is what's causing that sound, then everyone's compressor wheel would be shot by about 3k miles.

[rjspeed]

Is the HKS SSQV a short psht noise or a longer one? I know it depends on how fast you shift but even on a slow shift some BOV give off a very short psht instead of a long pshhhhhhhht.

[girth]

I have no scientific proof, but I'm quite certain that the flutter is caused by the turbo's compressor wheel surging and stalling. This surge and stall does not really harm the turbo because its compressor wheel is so tiny and because it is running such low boost pressure. All turbos make this sound to some small extent (you just can't always hear it), but a perfect BOV can eliminate the compressor surge and stall effect. On high boost engines (which the MSP most certainly is not) the compressor stall can damage the compressor wheel due to its increased inertia and can even unwind the compressor wheel from its shaft - which is why most "racing" competition turbos use a left-hand threaded shaft.

Try blowing into a fan and you'll get a similar sound. Air is hitting the turbo's compressor blades in the wrong direction.

[KyRaceFan]

when shifting fast, the HKS is a very quick high pitched shriek.
The greddy type s is usually a longer whistle...

[Striker187]

rjspeed - no pics, sorry. but just think about putting it somewhere close the outside of the car to maximize what you'll hear. those who choose to go this route generally put it near the intercooler. but from what i've always heard is that the rule of thumb is to place the bov close to the throttle body (quicker pressure? i dunno...). don't get me wrong, a bov placed near the throttle body will sound plenty loud.

there's really not that much of a difference in price. maybe $20. shop around, the greddy can be had for about $180 and the hks $190-210. if you wanna know what the hks will sound like, visit www.blowoffvalves.com. they have plenty of recordings of the hks....it's a favorite among supra owners.

girth - if it is compressor surge, why would tuned cars, such as the cars i mentioned above, have it then?

[girth]

Originally posted by Striker187
girth - if it is compressor surge, why would tuned cars, such as the cars i mentioned above, have it then?

Were they recirculating or blowing off to ATM? If blowing off, then I'd say their pressure relief screw was not adjusted perfectly (one of the reasons a BOV can be a pain in the arse). If they were recirculating, then I'm not sure ......... how big of turbo and how high of boost were they running? All of that factors into it. Personally I think nearly all turbos make this sound, just on different levels of "audibleness" (is that a word? lol)

[Striker187]

i'm pretty sure they were venting. just seems weird that the tuner would leave it set with compressor surge. these clips i saw were taken from best motoring vids (except for the is300...you'd think tuners would have their car perfectly set before letting them be driven by the testers.

[girth]

I agree that it is odd. And by no means am I an "expert" on the subject -- all of those guys with those cars are probably far more knowledgable than I am on the subject. Flat out, we need a turbo expert to get on this board.

[Sparkz28SS]

Originally posted by KyRaceFan
the "flutter" or "gobble" is compresser surge.


true true......



and you can try a bigass BOV,it willl help it for the most part.It helped out on my Z28...the flutter may not always be audible ...but it will never go away...

[girth]

Originally posted by Sparkz28SS
true true......



and you can try a bigass BOV,it willl help it for the most part.It helped out on my Z28...the flutter may not always be audible ...but it will never go away...

I concur.

[Striker187]

i wonder if the flutter will still remain when i get around to changing out the bpv....then i could make like a tuned jdm monster :D waaaaapshh, psssh, psssh, psssh!!!