Turbo noise and turbo flutter with GFB BOV

[Subru]

I have had my GFB BOV for a few months now and recently I noticed the turbo is fluttering around 2500rpm if I put foot down for about 2 seconds then lift off. The BOV is adjustable (preload and can switch between recirc or vent to atmosphere or in between)  so I played around with it but didnt seem to change much. Is it harmful having it flutter like that? When there is more turbo pressure then it will make the BOV noise and not the turbo flutter.

Another issue (prob not related to the BOV) with the turbo is that when its spooling up I hear a slight raspy noise, almost like bearing noise or something. 

[iludez]

That noise on spooling does it almost sound like something rattling inside a tin can?

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[Subru]

1 minute ago, iludez said:

That noise on spooling does it almost sound like something rattling inside a tin can?

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nah more of a consistent noise almost like the noise of sand paper rubbing on something but its not that loud, just noticeable.

[BeastGRB]

On 9/2/2017 at 9:39 AM, Subru said:

nah more of a consistent noise almost like the noise of sand paper rubbing on something but its not that loud, just noticeable.

 

Possibly a video? 

[THUNDA]

Sounds like compressor surge? you put your foot down, and before any/much boost is built up you take your foot off and it flutters?

nothing wrong with that imo, i always have my bov on full strength, because anything apart from full strength it makes a MASSIVE bov release and it sound even when im trying not to boost each gear lol. so i too get the flutter. if thats the case - no worries. but definately put a lil video to be sure imo.

 

Cant remember but didnt you do the snorkel delete? if you recently did then that will be exactly whats happened, youll hear what the bov does/doesnt do more than before

 

[Guest]

@THUNDA compressor surge is when you put your foot up it at low rpm and the turbo tries to force too much air into the engine which causes the compressor to chop the air. That's not real healthy for the turbo.

 

The dose pipe thing is bad for some turbos.

 

Easy way to tell between the 2 is ones on acceleration the others on lift off.

[SpeedySub]

 

[Subru]

Yep its on lift off and im pretty sure its what @THUNDA was saying so its all good. Just wanted to ask as I just heard it the first time a few days ago.

I might put a video of the other noise my turbo was making and I have not done the snorkel delete yet.

Also, for some reason sometimes my car randomly goes slow as if its not boosting properly, (happened 2 or 3 times now for about a few days to a week each time). After a few days or a week it does go back to its usual power. It does hit 18ish psi and drops straight back down which is normal for my car (hard to see tho coz boost gauge is hard af to read) but im deeply confused why it does this. Maybe my turbo is stuffed, along with the random losses of power, the raspy noise and the slow spool and quick drop of boost I imagine the turbo is has seen better days. Also there randomly is a weird oily/hot smell which I have no idea where its coming from.

[Guest]

If you have flutter it means the Bov is set too tight or doesnt flow enough. Fine line sometimes between too sift and flowing enough at lower throttle openings.

 

Easy way out is buy a holset and dont run a Bov then dose e'erday.

[THUNDA]

7 hours ago, evowrx said:

@THUNDA compressor surge is when you put your foot up it at low rpm and the turbo tries to force too much air into the engine which causes the compressor to chop the air. That's not real healthy for the turbo.

 

The dose pipe thing is bad for some turbos.

 

Easy way to tell between the 2 is ones on acceleration the others on lift off.

 

Yup, so just to clarify , the zut zut zut flutter noise is compressor surge? Or is there a different name for that?

[Guest]

43 minutes ago, THUNDA said:

 

Yup, so just to clarify , the zut zut zut flutter noise is compressor surge? Or is there a different name for that?

 

Commonly called that but it's more what they call dose or flutter. Also caused by a back feed of air when throttle plate shuts if there's not enough bov or there isn't one at all. 

 

Surge is when the turbo is spooling up too fast and the engine cant keep up with the airflow. It is when you are operating to the left of the surge line on a compressor map.

[iludez]

 
Yup, so just to clarify , the zut zut zut flutter noise is compressor surge? Or is there a different name for that?

Yep that is compressor surge.

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[Subru]

5 minutes ago, evowrx said:

 

Commonly called that but it's more what they call dose or flutter. Also caused by a back feed of air when throttle plate shuts if there's not enough bov or there isn't one at all. 

 

Surge is when the turbo is spooling up too fast and the engine cant keep up with the airflow. It is when you are operating to the left of the surge line on a compressor map.

is it bad for subi turbos to just make it fully dose and just make flutter noises all day long?  

I guess its okay on some turbos anyway because I heard an evo today making all kinds of flutter noises  

[Andy_Mac]

It doesn't have a 3-port boost control solenoid does it?

[Subru]

3 minutes ago, Andy_Mac said:

It doesn't have a 3-port boost control solenoid does it?

nope

[boon]

12 hours ago, Subru said:

is it bad for subi turbos to just make it fully dose and just make flutter noises all day long?  

I guess its okay on some turbos anyway because I heard an evo today making all kinds of flutter noises  

 

Depends who you ask. Do it enough and eventually it will probably shear the turbine shaft and the turbine will fall down the downpipe.

Then if you don't notice the absolutely horrible noise from your turbo, the compressor wheel will start remodelling itself (and the compressor cover) and feeding tiny shards of aluminium to your motor.

The noise you describe sounds like a leak, to me.

[Subru]

16 minutes ago, boon said:

 

Depends who you ask. Do it enough and eventually it will probably shear the turbine shaft and the turbine will fall down the downpipe.

Then if you don't notice the absolutely horrible noise from your turbo, the compressor wheel will start remodelling itself (and the compressor cover) and feeding tiny shards of aluminium to your motor.

The noise you describe sounds like a leak, to me.

oh so its not that bad then  

Yea I see, might check for leaks, any tips on how?  

[iludez]

oh so its not that bad then  

Yea I see, might check for leaks, any tips on how?  

@El_chado showed me this

 

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[YoungOne]

My understanding was that ball bearing turbos can handle flutter/dose ok while journal bearings can't really? Made sense to me as under thrust loading the journal bearings could contact metal to metal while a ball bearing would still function against those loads. 

 

Compressor Surge is just a bad time on any turbo

[boon]

1 hour ago, YoungOne said:

My understanding was that ball bearing turbos can handle flutter/dose ok while journal bearings can't really? Made sense to me as under thrust loading the journal bearings could contact metal to metal while a ball bearing would still function against those loads. 

 

Compressor Surge is just a bad time on any turbo

 

Sounds a bit mythological to me - journal bearings turbos have a thrust bearing for handling axial loads; although I'm not even sure that compressor surge would generate that much of an axial load.

 

[Subru]

Brett seems to think its aight to dose all day long (sort of)

 

[IZichard]

4 hours ago, Subru said:

Brett seems to think its aight to dose all day long (sort of)

 

This series of videos often annoys me because they take away from the "back yard" roots of MCM and lean towards buying expensive products. All he is doing here is blocking the blow of valve, just an expensive way of doing it. Could of achieved the same thing with a thin sheet of metal with two holes drilled in it.

[Subru]

8 hours ago, IZichard said:

This series of videos often annoys me because they take away from the "back yard" roots of MCM and lean towards buying expensive products. All he is doing here is blocking the blow of valve, just an expensive way of doing it. Could of achieved the same thing with a thin sheet of metal with two holes drilled in it.

I agree, I miss the good old days of them doing their Subaru builds and diy stuff. Now they even have imported a new ford focus rs and is going to be part of the channel for a while which like you say is far from their 'back yard' roots and its kinda lame...

In the video he also said that its probably okay as many people have done what he has done (or made the dose noise at least) and seemed to be okay but do it at your own risk as it does place more pressure on the turbo.