Which BOV makes the "turkey flutter" sound?
06-27-05 | 01:32 AM
#28
MattB
Joined: Apr 2005
Posts: 1,124
Likes: 0
From: Haverhill, MA
its not a BOV that makes that noise. that is a wastegate opening and closing repeatedly. the only reason people run BOV's is because it prolongs the life of your turbo. The WRC cars run wastegates because it improves performance. the BOV simply wastes all that air and makes the cool swoosh sound...wastegates are better for performance though.....
and the Starion is running 7 PSI boost...3 PSI less than stock...it doesnt run a BOV it runs a wastegate which is why it makes that sound
and the Starion is running 7 PSI boost...3 PSI less than stock...it doesnt run a BOV it runs a wastegate which is why it makes that sound
06-27-05 | 01:52 AM
#32
W. TX chirpin Monkey
Joined: Sep 2001
Posts: 2,684
Likes: 0
From: Mesquite, TX
I think you're referring to Compressor surge. Anyhow, you'd have to be an idiot to purchase a BOV based on how it sounds, not how it performs. OH well you're probably still running 15's anyway...that or you'll use the I'm a canyon carver excuse, for your inability to show up a sanctioned racing event.
06-27-05 | 02:07 AM
#33
set any bov too tight so the air cant blow off the air pressure. it causes is compressor surge but lets off air as it builds up, this causes it to flutter, its easiest with an rfl or a turbosmart bov. I cant beleive im answering this question
06-27-05 | 06:02 AM
#34
I'm a boost creep...
Joined: Jan 2002
Posts: 15,608
Likes: 8
From: Auckland, New Zealand
Originally Posted by SwiftTone
^^^Uhhh, I dont want a compressor surge. I said theres a BOV that makes a turkey gobble sound, not make the compressor surge. JEEEEEEEZ, lol.
If you are desperate for attention (why else would you do this) want your car to make stupid turkey sounds, pull the vac line off the BOV and cap it. Then crank the boost up to stupid levels and you'll get the noise you want. Plan to replace the turbo and/or engine soon...
06-27-05 | 06:38 AM
#35
Haven't we ALL heard this
Joined: Mar 2001
Posts: 3,948
Likes: 1
From: Indiana
Originally Posted by MattB
its not a BOV that makes that noise. that is a wastegate opening and closing repeatedly. the only reason people run BOV's is because it prolongs the life of your turbo. The WRC cars run wastegates because it improves performance. the BOV simply wastes all that air and makes the cool swoosh sound...wastegates are better for performance though.....
and the Starion is running 7 PSI boost...3 PSI less than stock...it doesnt run a BOV it runs a wastegate which is why it makes that sound
and the Starion is running 7 PSI boost...3 PSI less than stock...it doesnt run a BOV it runs a wastegate which is why it makes that sound
WRC cars run wastegates because it improves performance?
If ANY turbocharged car did not have a wastegate you could not control boost....
The BOV prevents compresor surge and does NOTHING to control boost.
Maybe you just got your terms mixed up
James
06-27-05 | 07:21 AM
#36
i heard the reason for bov valves for several reasons,
1. turbo life
2. blowing off the exxess pressure alows the turbo to keep spooled, just venting, where as when the compresser surge occures it slows down the turbines speed, which means you need more time to spool it up again when u go full throttle again!
now to ruin everything! i wanna attach a duck call to it!!! ROFL
1. turbo life
2. blowing off the exxess pressure alows the turbo to keep spooled, just venting, where as when the compresser surge occures it slows down the turbines speed, which means you need more time to spool it up again when u go full throttle again!
now to ruin everything! i wanna attach a duck call to it!!! ROFL
06-27-05 | 07:28 AM
#37
Full Member
Joined: Jul 2003
Posts: 123
Likes: 1
From: Qld, Australia
OK we had this discussion on ausrotary before and you can check it out at http://ausrotary.dntinternet.com/for...hlight=flutter. Here is a couple of nice little posts by burn4005 that explains compressor surge as he was getting extremely pissed off by people calling it wastegate flutter.
Hope thats cleared a few things up.
sorry to do this but.
i was having a chat to a few guys the other night that are into cars but take them to shops to get everything done etc and a vl went past and fluttered its **** off.
one of the cluey boys said: "**** man, did you hear that guys wastegate??, fully sik"
i couldn't contain my self.
Explanation:
___________________________
for the record 'flutter' is Compressor Blade Reversion
wastegates dont, wont, cant flutter. do some practical experimentation and
remove your blow off valve (if you have one, just to induce more flutter so its more obvious because you obviously have mental health issues to think wastegates flutter) and tell me if flutter occurs at below full boost. OH??? WHAT???? IT DOES????
go one step further, WELD your wastegate shut, or remove it (weld a plate there istead.. wow i get wastegate flutter, with no wastegate?? fantastic.
so guess what? you can get 'wastegate' flutter when your manifold pressure hasn't even reached the level that your wastegate actually actuates.
this means its CLOSED. CLOSED wastegates do not do anything at all.
if you boost your car to say, 7psi, and you have an e-boost set for 16 with a very steep boost ramp, then back off, you get flutter dont you?
the wastegate hasnt recieved any pressure signal throught the e-boost solenoid so its not going anywhere therefore, an inactive/closed wastegate wont do jack.
one more point: why do you get louder flutter with an open pod filter compared with a closed airbox???
why is flutter more pronouced when you increase the volume of your post-turbo inlet tract (big front mount)???
you wastegate is on the opposite end of proceedings and is totally irrelivant.
in summary:
WASTEGATES DONT CAUSE FLUTTER.
COMPRESSOR BLADE REVERSION DOES, DUE TO A PRESSURE WAVE COMING FROM A CLOSED THROTTLE PLATE HITTING YOUR 70,000 - 100,000 RPM COMPRESSOR BLADES.
the reason it is more pronounced with a huge front mount is that the time between 'bounces' in increased due to a larger distance and volume between throttle and compressor (piping and intercooler)
Ahh.. much better
/end rant
[edited to be 100% correct so people dont get confused.
changed cavitation to reversion and turbine to compressor.]
(i made a few mistakes in the heat of the moment haha )
i was having a chat to a few guys the other night that are into cars but take them to shops to get everything done etc and a vl went past and fluttered its **** off.
one of the cluey boys said: "**** man, did you hear that guys wastegate??, fully sik"
i couldn't contain my self.
Explanation:
___________________________
for the record 'flutter' is Compressor Blade Reversion
wastegates dont, wont, cant flutter. do some practical experimentation and
remove your blow off valve (if you have one, just to induce more flutter so its more obvious because you obviously have mental health issues to think wastegates flutter) and tell me if flutter occurs at below full boost. OH??? WHAT???? IT DOES????
go one step further, WELD your wastegate shut, or remove it (weld a plate there istead.. wow i get wastegate flutter, with no wastegate?? fantastic.
so guess what? you can get 'wastegate' flutter when your manifold pressure hasn't even reached the level that your wastegate actually actuates.
this means its CLOSED. CLOSED wastegates do not do anything at all.
if you boost your car to say, 7psi, and you have an e-boost set for 16 with a very steep boost ramp, then back off, you get flutter dont you?
the wastegate hasnt recieved any pressure signal throught the e-boost solenoid so its not going anywhere therefore, an inactive/closed wastegate wont do jack.
one more point: why do you get louder flutter with an open pod filter compared with a closed airbox???
why is flutter more pronouced when you increase the volume of your post-turbo inlet tract (big front mount)???
you wastegate is on the opposite end of proceedings and is totally irrelivant.
in summary:
WASTEGATES DONT CAUSE FLUTTER.
COMPRESSOR BLADE REVERSION DOES, DUE TO A PRESSURE WAVE COMING FROM A CLOSED THROTTLE PLATE HITTING YOUR 70,000 - 100,000 RPM COMPRESSOR BLADES.
the reason it is more pronounced with a huge front mount is that the time between 'bounces' in increased due to a larger distance and volume between throttle and compressor (piping and intercooler)
Ahh.. much better
/end rant
[edited to be 100% correct so people dont get confused.
changed cavitation to reversion and turbine to compressor.]
(i made a few mistakes in the heat of the moment haha )
next lesson, Compressor surge and stall.
the flutter that occurs in your turbo car occurs because air comes back from your closed throttle plate and hits the compressed air coming from your turbo, inducing something called Compressor Surge.
a typical surge event consists of high pressure spike followed by a sharp drop in pressure and then a slow recovery back to the stable operating point pressure.
the image above shows several surge cycles (in the blue trace). a significant low momentum fluid blockage develops in the diffuser at a stable operating point just above the stalling mass flow. With a further constriction of the mass flow, the blockage in the diffuser cause the large pressure spike observed at the start of the surge cycle (the begining of flutter). Furthermore, during the high pressure spike (closing your throttle plate), the flow in the diffuser completely reverses and flows up into the vaneless space (the snail shape of your compressor cover). the green parts on either side of the red section, are trying to flow into the red section (towards eachother and meet), hence the volume of high pressure), as shown below.
At the point of minimum pressure in the diffuser, forward flow in the turbo is reestablished (this is because your turbo is still spinning and trying to compress air, but the high pressure shock in the outlet hasn't let it until this point) in the form of a supersonic shock front that propagates back down through the outlet as shown below:
The supersonic shock front forces the remnants of the reversing flow out of the diffuser, producing a Low pressure zone in the compressor outlet.
As the pressure slowly recovers in the compressor outlet, the high speed flow subsides and the flow field approaches the stable operating point conditions of high speed flow entering the compressor and low speed flow within/exiting the compressor outlet (the air coming out of your compressor is still traveling fast, but compared to the atmospheric pressured air entering, it is considered low velocity relative to the intake).
the reverse flow occurring during compressor surge is influenced by the pressure waves emanating from the passing compressor blades. it has been shown that pressure fluctuations in the compressor housing/outlet are caused by pressure waves emanating from the impeller blades.
end final lesson and i hope everyone understands.
(thanks to nasa for the images, these are from a paper they published on variable compressor geometry to eliminate surge/stall in variable duty compressor systems)
the flutter that occurs in your turbo car occurs because air comes back from your closed throttle plate and hits the compressed air coming from your turbo, inducing something called Compressor Surge.
a typical surge event consists of high pressure spike followed by a sharp drop in pressure and then a slow recovery back to the stable operating point pressure.
the image above shows several surge cycles (in the blue trace). a significant low momentum fluid blockage develops in the diffuser at a stable operating point just above the stalling mass flow. With a further constriction of the mass flow, the blockage in the diffuser cause the large pressure spike observed at the start of the surge cycle (the begining of flutter). Furthermore, during the high pressure spike (closing your throttle plate), the flow in the diffuser completely reverses and flows up into the vaneless space (the snail shape of your compressor cover). the green parts on either side of the red section, are trying to flow into the red section (towards eachother and meet), hence the volume of high pressure), as shown below.
At the point of minimum pressure in the diffuser, forward flow in the turbo is reestablished (this is because your turbo is still spinning and trying to compress air, but the high pressure shock in the outlet hasn't let it until this point) in the form of a supersonic shock front that propagates back down through the outlet as shown below:
The supersonic shock front forces the remnants of the reversing flow out of the diffuser, producing a Low pressure zone in the compressor outlet.
As the pressure slowly recovers in the compressor outlet, the high speed flow subsides and the flow field approaches the stable operating point conditions of high speed flow entering the compressor and low speed flow within/exiting the compressor outlet (the air coming out of your compressor is still traveling fast, but compared to the atmospheric pressured air entering, it is considered low velocity relative to the intake).
the reverse flow occurring during compressor surge is influenced by the pressure waves emanating from the passing compressor blades. it has been shown that pressure fluctuations in the compressor housing/outlet are caused by pressure waves emanating from the impeller blades.
end final lesson and i hope everyone understands.
(thanks to nasa for the images, these are from a paper they published on variable compressor geometry to eliminate surge/stall in variable duty compressor systems)
06-27-05 | 08:41 AM
#38
MattB
Joined: Apr 2005
Posts: 1,124
Likes: 0
From: Haverhill, MA
that actually makes a lot of sense. i guess me and my friend have been wrong for a long *** time because we are only 17...dont know a whole lot....and never really took the time to learn i guess. just assumed. guess that starions wastegate is broken or just not set right. ill have to let him know. thanks for clearing everything up.
so im assuming the flutter on WRC cars is cause by what someone said earlier...just a LOT of boost and the BOV's cant release it all quick enough.
also...could this be causing the fins on his turbo to bend after a while. he cant get full boost....and the fins on the turbo are bend and broken. after a long time like this, is that possible?
so im assuming the flutter on WRC cars is cause by what someone said earlier...just a LOT of boost and the BOV's cant release it all quick enough.
also...could this be causing the fins on his turbo to bend after a while. he cant get full boost....and the fins on the turbo are bend and broken. after a long time like this, is that possible?
06-27-05 | 01:00 PM
#39
Ready to Rock
Joined: Jun 2002
Posts: 726
Likes: 0
From: Bergen County, NJ
If you're talking about the high pitched chirping sound, get an HKS SSQV or Greddy Type S. www.blowoffvalves.com has a bunch of sound clips for different BOVs.
06-27-05 | 02:18 PM
#40
Custom User Title
Joined: Nov 2003
Posts: 235
Likes: 0
From: nebraska
06-27-05 | 02:28 PM
#41
MattB
Joined: Apr 2005
Posts: 1,124
Likes: 0
From: Haverhill, MA
just do that with something that makes a turkey flutter sound haha.....
so ive been trying to make this all make sense and from what i understand.......
a wastegate has a stronger diaphram. this means that when it gets to a certain boost level it opens...then when its below that level it closes. for example:
the wastegate is set to open at 7PSI. the cars turbo spools then gets above 7 psi then the wastegate opens....it release down to just below 7 psi then closes. when it closes the turbo is still creating pressure so it brings it back above 7 psi and it opens again...then it does that over and over thus creating the TURKEY FLUTTER noise you are hearing.
a blow off valve simply lets all the pressure out.
the reason WRC cars are running wastegates is because its holds boost better and improves performance.
the reason most people run BOV's is because it lengthens turbo life, and sounds cool....
correct me if im wrong but thats what i am getting out of this....
-Matt
so ive been trying to make this all make sense and from what i understand.......
a wastegate has a stronger diaphram. this means that when it gets to a certain boost level it opens...then when its below that level it closes. for example:
the wastegate is set to open at 7PSI. the cars turbo spools then gets above 7 psi then the wastegate opens....it release down to just below 7 psi then closes. when it closes the turbo is still creating pressure so it brings it back above 7 psi and it opens again...then it does that over and over thus creating the TURKEY FLUTTER noise you are hearing.
a blow off valve simply lets all the pressure out.
the reason WRC cars are running wastegates is because its holds boost better and improves performance.
the reason most people run BOV's is because it lengthens turbo life, and sounds cool....
correct me if im wrong but thats what i am getting out of this....
-Matt
06-27-05 | 02:50 PM
#42
Haven't we ALL heard this
Joined: Mar 2001
Posts: 3,948
Likes: 1
From: Indiana
Originally Posted by MattB
the reason WRC cars are running wastegates is because its holds boost better and improves performance.
the reason most people run BOV's is because it lengthens turbo life, and sounds cool....
correct me if im wrong but thats what i am getting out of this....
-Matt
There is no other way to control boost on a turbo automaticly. Unless you have a VATN turbo. Which varies the angle of the turbine blade to slow or speed up the compressor to control boost.
A wastegate and a BOV are two completly different things serving two complettly different purposes.
James
06-27-05 | 08:10 PM
#45
The mystery of the prize.
Joined: Aug 2002
Posts: 832
Likes: 2
From: Bay area
http://media.scandalousracing.com/vi...o_vs_titan.wmv
If the sound you are referring to is what you hear when marcos white supra does it's burnout in that video, you're describing compressor surge.
The car had no BOV at that event, it does have a wastegate however (of course).
If the sound you are referring to is what you hear when marcos white supra does it's burnout in that video, you're describing compressor surge.
The car had no BOV at that event, it does have a wastegate however (of course).
06-28-05 | 04:01 AM
#47
I'm a boost creep...
Joined: Jan 2002
Posts: 15,608
Likes: 8
From: Auckland, New Zealand
Originally Posted by Camrann
Im pretty sure the wastegate is the fluttering sound.
Anyway, just to add to the excellent info on BOV's, here's some more from AutoSpeed. Real-world, no-BS testing:
"So how often have you see a BOV actually tested for its ability to reduce the pressure spike that occurs when you shut the throttle on a hard-blowing turbo? Not very often, right? And in fact, what does that pressure spike actually look like?
We decided to do some high-speed logging of the pressures that occur in the intake system between the turbo and the throttle blade when you snap the throttle shut. We used a Fluke 123 digital Scopemeter and a Fluke pressure transducer.
This screen grab shows the pressures with the electronically controlled Goyen BOV working. Each vertical division is the equivalent of 20 kPa (about 3 psi) manifold pressure and each horizontal division is 200 milliseconds. So from far left, the car is holding 70 kPa, grading down slightly to 60 kPa (about 9 psi) before the throttle is suddenly closed. The pressure abruptly spikes by 10 kPa (about 1.5 psi) but the spike is very short-lived (about 50 milliseconds) before it rapidly and smoothly falls away. In fact, the pressure drops from the spike of 70 kPa down to 20 kPa in less than 100 milliseconds (ie one tenth of a second). The fall to less than 10 kPa takes about 650 milliseconds (ie 0.65 seconds) in total.
And what a different story there is without the BOV working!
Again the throttle was abruptly closed at 60 kPa boost. The immediate pressure spike was about 15 kPa (only a little higher than without the BOV) but what follows from there is completely different. Rather than dying away quickly, the pressure is both much slower to fall off and is also accompanied by very rapid pressure waves, with these waves starting off at about 20 kPa peak-to-peak and then gradually dropping to about 10 kPa. The frequency of these varies from 15-20Hz. In other words, there is a pressure wave of up to 20 kPa racing up and down the intake system between the throttle and the turbo. It is very likely that this wave battering against the turbo compressor is potentially much more damaging that the initial pressure spike itself. Also note that the trapped pressure takes a lot longer to decrease – to drop to 20 kPa takes about 500 milliseconds (half a second) compared with one-fifth of that when a BOV is fitted."
06-28-05 | 05:11 AM
#49
Passing life by
Joined: Feb 2005
Posts: 4,028
Likes: 2
From: Scotland, USA
Oh my! I have avoided this thread for a few days now knowing what the outcome would be. I board so I reading it. Boy am I glad I did. Started off laughing histaricly, and then it suddenly got good with great posts and wisdom shared.
Thanks NZ and RX7 for your knowledgeable posts.
I want my car to gobble ROFL! Do I hear thx giving peraid?
Thanks NZ and RX7 for your knowledgeable posts.
I want my car to gobble ROFL! Do I hear thx giving peraid?
06-28-05 | 05:58 AM
#50
Haven't we ALL heard this
Joined: Mar 2001
Posts: 3,948
Likes: 1
From: Indiana
Originally Posted by NZConvertible
Anyway, just to add to the excellent info on BOV's, here's some more from AutoSpeed. Real-world, no-BS testing:
"So how often have you see a BOV actually tested for its ability to reduce the pressure spike that occurs when you shut the throttle on a hard-blowing turbo? Not very often, right? And in fact, what does that pressure spike actually look like?
"So how often have you see a BOV actually tested for its ability to reduce the pressure spike that occurs when you shut the throttle on a hard-blowing turbo? Not very often, right? And in fact, what does that pressure spike actually look like?
James