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FLUTTER sound as BOV

ATTN

By ATTN,
in Engines & Forced Induction

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paulr33 Grand Master

paulr33

Posted
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the three stooges noise or the flutter is the air hitting the compressor wheel and being chopped. go find a pedestal fan and talk into the back of it, your voice will be chopped, much the same way the air in the turbocharger system is chopped, when you don't use a BOV

DazWah Collaborator

DazWah

Posted
Posted (edited)

to get the sound you need a metal intake pipe instead of the plastic one with no air filter, also move the afm to somewhere on the cold side of the cooler, also block off BOV. That should do to get the sound of vl's.

Edited by DazWah
assyrian4evaa Proficient

assyrian4evaa

Posted
Posted
vl turbo owners will call it wastgate flutter

most people want to buy an external gate for flutter

or think a screamer pipe gives you flutter

the two are not related

thats my reason for asking this question dis guy(vl turbo owner) goes 2me bro get a ext. waste gate and u'll have the nice vl flutter i tried explaining wat a wastegate does but he still thot it had something 2do with the sound...

AndrewD Contributor

AndrewD

Posted
Posted
thats my reason for asking this question dis guy(vl turbo owner) goes 2me bro get a ext. waste gate and u'll have the nice vl flutter i tried explaining wat a wastegate does but he still thot it had something 2do with the sound...

thats because your both idiots :)

you dont need to do anything. if you've got compressor surge you can hear it. one way to get it is to block off your recirculation valve.

asides from people already suggesting that compressor surge, flutter chatter whatever you call it does not harm turbocharger function and componentry its well documented in the engineering realm that it does.

there are too many gits and internet mechanics that speel shit on here that its just so funny.

im not saying dont do it, its your choice. just be prepared to spend the money for reconditioning or potential engine rebuilds from destroyed compressor wheels.

assyrian4evaa Proficient

assyrian4evaa

Posted
Posted
thats because your both idiots :D

you dont need to do anything. if you've got compressor surge you can hear it. one way to get it is to block off your recirculation valve.

asides from people already suggesting that compressor surge, flutter chatter whatever you call it does not harm turbocharger function and componentry its well documented in the engineering realm that it does.

there are too many gits and internet mechanics that speel shit on here that its just so funny.

im not saying dont do it, its your choice. just be prepared to spend the money for reconditioning or potential engine rebuilds from destroyed compressor wheels.

well if u read my thread mr smart ass i didnt say anything about the sound not being due to compressor surge thats wat i was trying 2explain to ur mate in the vl that thot its a wastegate n crap like that..

VL guys even have a tutorial on how to 'dose'. Seriously that forum is such a laugh sometimes

i still dont understand wat this DOSE PIPE thing is?? or is it just a word for vl owners

justin911 Grand Master

justin911

Posted
Posted

since i got my new turbo the other day my car makes the fluttery noise when im driving with just a little bit of boost sometimes.. never if its above 7psi or so though..if its bad for the turbo how do i make it never do it ?? im using the stock bov and airbox.

Link Proficient

Link

Posted
Posted

Just had this same argument on another forum

Ill copy and paste what i wrote

Turbo failure due to no BOV is bullshit, it technically can not happen ! I challenge anyone to show me the numbers behind how this can happen. I will save you the effort, you cant

You want to hear turbo flutter, you need to listen to one of these old school videos, sometimes you can just hear it over the exhaust especially on entry to a braking zone or in mid corner

Blades bending back and shafts snapping is rubbish, air is very very light stuff and it physically cannot do any of this no matter how good peoples imagination is. Dont confuse this with a NOS or fuel system backfire which can blow a plenum apart, though they dynamics of this phenomenon has nothing at all to do with not running a BOV.

History on turbo race machines proves it.

Every International Group C sports car to 1991 NO BOV

Every F1 car from 1979 to 1988 NO BOV

Every Indy car from 1970 to NOW NO BOV

DJR Group A Sierra till its last races NO BOV

Porsche GT1 Top Gear - Listen to the flutter

http://www.youtube.com/watch?v=5LtkSCaE0EM

There are shit loads of examples across many different classes running every type of turbo you care to mention running at the thermal/mechanical limits for massive durations of time (24hr races) at very very high pressure ratios never ever experience failures of the type some people on this board and BOV maufacturers mention is trash publications.

I have a text (published in 1989) written by racecar engineering going into massive detail about only 1000bhp turbo F1 engines and NO WHERE do they mention the phenomenon that some people go on about. No where in history in motorsport do you see such failures due to not running a BOV, WHY ? Because its bullshit ! Plain and Simple

You want a current example from Japan (the home of the BOV), find a down load of Rod Millens Toyota Tacoma truck (runs 1000bhp 4 cyl single turbo) and it runs NO BOV, turbo flutter in all its glory

In the end it comes down to your own personal comfort level and personal feelings on a subject, if you cant or dont want to run just a WG then you need a BOV, but please dont come up with rubbish statements that not running one cause failures, history (current and past) and physics proves that no such things can happen.

This is not an attack on anyone, its more a statement of facts as they relate to many examples from some of the most leading/respected race engine engineers of ALL TIME, from the greatest ever period of turbo charged race engines F1 from 1983 to 1987. BOV's are never mentioned as they were never required. Same in old publications like Turbochargers by Hugh McInnes, not one farking BOV mention in whole text ! They are a falicy of the highest order and people selling them are perpetuating lies by stating that they should be mandatory in high boost high HP applications. Complete and utter rubbish !!!!!

In the nissan texts that i have read all the factory bov are used for is to muffle sound, nothing else

/End Essay lol

AndrewD Contributor

AndrewD

Posted
Posted
Just had this same argument on another forum

Ill copy and paste what i wrote

Turbo failure due to no BOV is bullshit, it technically can not happen ! I challenge anyone to show me the numbers behind how this can happen. I will save you the effort, you cant

You want to hear turbo flutter, you need to listen to one of these old school videos, sometimes you can just hear it over the exhaust especially on entry to a braking zone or in mid corner

Blades bending back and shafts snapping is rubbish, air is very very light stuff and it physically cannot do any of this no matter how good peoples imagination is. Dont confuse this with a NOS or fuel system backfire which can blow a plenum apart, though they dynamics of this phenomenon has nothing at all to do with not running a BOV.

History on turbo race machines proves it.

Every International Group C sports car to 1991 NO BOV

Every F1 car from 1979 to 1988 NO BOV

Every Indy car from 1970 to NOW NO BOV

DJR Group A Sierra till its last races NO BOV

Porsche GT1 Top Gear - Listen to the flutter

http://www.youtube.com/watch?v=5LtkSCaE0EM

There are shit loads of examples across many different classes running every type of turbo you care to mention running at the thermal/mechanical limits for massive durations of time (24hr races) at very very high pressure ratios never ever experience failures of the type some people on this board and BOV maufacturers mention is trash publications.

I have a text (published in 1989) written by racecar engineering going into massive detail about only 1000bhp turbo F1 engines and NO WHERE do they mention the phenomenon that some people go on about. No where in history in motorsport do you see such failures due to not running a BOV, WHY ? Because its bullshit ! Plain and Simple

You want a current example from Japan (the home of the BOV), find a down load of Rod Millens Toyota Tacoma truck (runs 1000bhp 4 cyl single turbo) and it runs NO BOV, turbo flutter in all its glory

In the end it comes down to your own personal comfort level and personal feelings on a subject, if you cant or dont want to run just a WG then you need a BOV, but please dont come up with rubbish statements that not running one cause failures, history (current and past) and physics proves that no such things can happen.

This is not an attack on anyone, its more a statement of facts as they relate to many examples from some of the most leading/respected race engine engineers of ALL TIME, from the greatest ever period of turbo charged race engines F1 from 1983 to 1987. BOV's are never mentioned as they were never required. Same in old publications like Turbochargers by Hugh McInnes, not one farking BOV mention in whole text ! They are a falicy of the highest order and people selling them are perpetuating lies by stating that they should be mandatory in high boost high HP applications. Complete and utter rubbish !!!!!

In the nissan texts that i have read all the factory bov are used for is to muffle sound, nothing else

/End Essay lol

I have few points to rebutt,

-The physics do suggest it can happen. In applications where the throttle is POST compressor, when it is closed you increase the pressure between the compressor and the throttle. As pressure increases, pressure ratio sky rockets. Most compressors for road cars (not race cars especially F1) operate with a maximum pressure ratio of no greater than 2. Above this surge occurs (but not only under this condition). Surge also occurs when the throttle is closed, the compressor cannot 'push' the air any further and it reverts and flows over the tips of the blades. As JC Marhsall stated earlier this creates vibrations in the blades and coupled with high hydrodynamic pressure loadings on the blades (at a distance from the blade / wheel interface) this causes them to bend or shear. It happens, go to garrett they have plenty of compressor wheels on display that have failed due to surge.

-Racecar engines that have not failed. I call dibs on this one. Lets define a racecar shall we. I think you will find that most racecars especially in the elite class, are often rebuilt after every race and the majority of their parts replaced. Not to mention that typical race cars with turbo applications run high boost (higher pressure ratios ie around 4 or 5) this means that compressor wheels are larger, and have a greater saftey against failure. However,

I would like to point out that most of the earlier F1 cars had PRE compressor throttle. This means that while the the throttle is closed, still increasing pressure ratio, the engine is unhibited to breath the pressurised air. And this surge doesnt occur. Rather now you get cavitation. The need to run a recirculation valve to 'raise the inlet pressure' is not so pronounced and typically improved seals are all thats required.

-Before you start complaining that people are getting all upset about falous claims, take the time to read many of Society of Automotive technical papers on this 'phenomenon' as you put it. Why do you think most compressor applications outside of automotive use are constant throttle / load?

I'll leave you with something to think about, being as it is i have access to a race engine using a garrett GT15v (yes its small, but its also the very same kind used on the new porche engines) we have a shaft speed sensor and have clocked it at in excess of 200,000 rpm. Now consider that you have surge at a pressure ratio of 3. Almost instantaneously the shaft speed changes to 0. Now no matter how light that wheel is, there is a significant amount of inertia force on the blades which is tramsitted to the key and shaft.

So before you go all internet mechanic on everyone, do some research. Peace out.

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