flutter or dump....? how about both.. read on

Dub-Se7en

Dub-Se7en

Lifer
Paul_JJ said:
Great thread, thx for that. I'll do it! So why exactly the fluttering is bad for turbo? I thought the standard BOV does the same but doesnt make any sound it spins it back isn't it?
Click to expand...

the standard BOV is the same as an atmospheric one in function, just the air is dumped back into the intake tract rather than to atmosphere, reducing the noise.

flutter is bad as it is essentially boost being shoved backed through the turbo the wrong way, causing the blades to slow very quickly and putting unnecessary pressure on the bearings. the jury is out on what long term damage it causes.
 
N

N80Jamie

Fresh Recruit
I've done this on mine but my turbo flutters on hi and low boost setting when stationary. Is this supposed to happen or..? If it is not supposed to be like this what do you think the problem could be? I've already replaced the solenoid so can't be that :/

I would go out and drive the car to find out the answer to my first question but I have no insurance yet :( aha
 
corofin12345

corofin12345

Member +
N80Jamie said:
I've done this on mine but my turbo flutters on hi and low boost setting when stationary. Is this supposed to happen or..? If it is not supposed to be like this what do you think the problem could be? I've already replaced the solenoid so can't be that :/

I would go out and drive the car to find out the answer to my first question but I have no insurance yet :( aha
Click to expand...

ull have to take it for a spin to get the boost up under load bud ;)
 
Reeco

Reeco

Member +
N80Jamie said:
So everyones turbo will flutter on either boost setting while stationary? :)
Click to expand...

you will get low rev chatter even with a BOV set up normaly in most cases , its alot more noticeable when your stationairy and due to no road noise your more likley to hear it, it will still make the noise even when your moving as long as you let of the accelerator at lowish revs :)
 
R

Rev

Member +
I seem to be getting dump at low boost and dump plus flutter together at high boost. Basically I have a smaller outlet to the dump value which stops flutter up to about 3000rpm ( warm day ) after that I also get dump ( whistle ) and flutter.

1 My thought was stalling the blades with flutter at low revs was not good for performance and can result in lag by stalling when you don't have much spinning pressure.

2 On the other hand having some dump when fluttering means the flutter pressure on the bearings is reduced a little .

3 At high revs while dumping i am still keeping all the inlet tract fully charged as dump is at the turbo which means I have no lag if I back off the throttle at gear stick changes as my electric semi-auto changes instantaneously .
 
corofin12345

corofin12345

Member +
an adjustable bov will cure this but not all of it.. the hks ssqv is the best one out there for getting rid of flutter but on the other hand, if you let out the throttle easily every setup will create flutter.. some people think they have light flutter sometimes but the fact is the stock efi pipe will dampen alot of the flutter noise.. i know this first hand cause i relocated my filter and the flutter was way louder due to shorter route to turbo inlet..
 
GTti

GTti

Member +
To be honest I don't care much either way for atmospheric venting valves.

People seem to forget that regardless of compressor flutter the turbo is working against bi directional forces all of the time. Those forces are generated from high velocity exhaust gasses on one side and for example 1BAR of resistance on the intake side - these are two forces in either direction. By closing the throttle body you are momentarily increasing the pressure in the intake side, forcing some air out through the path of least resistance.

Turbos fail regardless of application, most shaft bearings are floating and will eventually wear under normal use. If I were to use a BOV in a high boost application it would be situated right near the TB, but I have had no form of valve in a lower boost application where it's lasted 85k miles - so they're clearly not essential in lower boost scenarios.
 
Last edited:
R

Rev

Member +
corofin12345 said:
an adjustable bov will cure this
Click to expand...

Yea that would be better. A bigger outlet that had a blow off valve that could be adjusted larger or smaller to suit the setup.
I find the smaller outlet is too small sometimes eg. changing from 2nd to 5th , massive
flutter and shudder as the air is too much.

Would rep you but dont have rep. maybe someone could rep coro for me.
 
corofin12345

corofin12345

Member +
Rev said:
Yea that would be better. A bigger outlet that had a blow off valve that could be adjusted larger or smaller to suit the setup.
I find the smaller outlet is too small sometimes eg. changing from 2nd to 5th , massive
flutter and shudder as the air is too much.

Would rep you but dont have rep. maybe someone could rep coro for me.
Click to expand...

no bother bud.. its also importand to keep your bov clean.. over a few months (depends what your sucking up) the piston will get sticky so a quick clean can help the situation aswell
 
R

RichielightweightGT

Member +
i have to say very very cool, but the flutter can cause failure of the turbo i am a poor misfortunate of this, turbo was fine running well when my dump valve decided its going on strike and not dumping anymore lol but with this that super cool flutter came along and i said id leve it as is lol short time later i startd losing boost in the higher revs so i took off the turbo and my intake fins were chewd up so took off my top mount tipped out the bits of turbo fins and fitted new turbo and dump valve lol, anyway my gf had a gt perescent blue its for sale again on done deal no one seems to keep it long :S but it has a fluttery dumpvalve in it so you can buy a dumpvalve to make that sound without the chance of doing damage no?
 
corofin12345

corofin12345

Member +
RichielightweightGT said:
i have to say very very cool, but the flutter can cause failure of the turbo i am a poor misfortunate of this, turbo was fine running well when my dump valve decided its going on strike and not dumping anymore lol but with this that super cool flutter came along and i said id leve it as is lol short time later i startd losing boost in the higher revs so i took off the turbo and my intake fins were chewd up so took off my top mount tipped out the bits of turbo fins and fitted new turbo and dump valve lol, anyway my gf had a gt perescent blue its for sale again on done deal no one seems to keep it long :S but it has a fluttery dumpvalve in it so you can buy a dumpvalve to make that sound without the chance of doing damage no?
Click to expand...

if your blades are chewed up its nothing got to do with flutter bud.. something had to off gotton into the inlet to chew up the blades from the outside.. theres no such thing as a fluttery dumpvalve.. if its adjustable its wound in too tight, that or the piston is sticking in the dumpvale and needs to be taken apart and cleaned.. ive been running with flutter the last year and my turbo is still perfect.. as said in other posts, i wouldnt recommend it on bigger boost setups
 
R

RichielightweightGT

Member +
tbh i nt tryn t start a debate on this lol but i had a brand new induction kit and before that standard airbox + filter so if something got in i dont knw where it would have got in the efi pipe was securely mounted and theres no hole or anything in it, only thing i can think of is that it upset the shaft bearings and cause an imbalance which left the blades rub against the housing either way i still think its cool lol
 
corofin12345

corofin12345

Member +
your turbo juas may of been on its last legs bud... perfect one day and blowen the next.. happens alot on these cars.. if thats the case tho your the very first ive seen it happen to
 
R

RichielightweightGT

Member +
it could only happen to me tbh lol ive got a new ct9b planning on external waste gate i hav a gutted cat and boost creep is my enemy ha ha this will be my 4th turbo the one in it is fine but i suspect oil seals could be getting knackerd its a glanza one again but im not driving the car daily so it will be fine until i get my mani nd all sorted hi/lo dumpvalve FTW :p
 
T

turbominicooper

Member +
quick question:

You have mentioned in the orignal post that this will only work on an aftermarket BOVs... shouldn flutter occur wether the dv is standard or not?
 
T

turbominicooper

Member +
ah right, is there anyway of opening the standard one and fitting a higher pressure spring ? also which was dump and which was flutter (hi/low)??
 
You must log in or register to reply here.
Top