Understanding BPV Flutter - Page 2 - Subaru WRX Forum
 27Likes
Reply
 
LinkBack Thread Tools Display Modes
#16 Old 10-15-2013, 06:32 AM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
So would a leak make me experience flutter?

Keith, can you tell me whether this is def flutter and not surge at this point?


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
Sponsored Links
Advertisement
 
#17 Old 10-15-2013, 07:53 AM
Premium Member
 
boo-key bear's Avatar
 
Join Date: Dec 2008
Location: Tennessee
Posts: 1,161
Images: 6
boo-key bear is known to be trustworthy and helpful boo-key bear is known to be trustworthy and helpful
Garage
Quote:
Originally Posted by psinuse View Post
Sounds like surge to me...
Definitely wastegate flutter and not compressor surge in my case.


Brandon, I would consult with your tuner then follow his diagnosis and recommendations. Curious, did this just start recently without any changes to your set-up or has it always done this? Which bpv do you have (too lazy to go to your profile)? Hope you figure it out and keep us informed! Knowledge is power!

*edit* Got un-lazy and saw it's a Forge.

Adair
06' wrx tr
Phatbotti tuned!

Last edited by boo-key bear; 10-15-2013 at 02:17 PM.
boo-key bear is online now  
#18 Old 10-15-2013, 08:59 AM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
Yup I run a Forge BPV. Yellow spring w/ 2 shims (recommended by tuner)

No changes in anything since last fall

Emailed my tuner. Will post his reply for others as well with future questions.

Also PM'd a guy I found commenting on similar threads to mine on NASIOC who seemed pretty nice and quite knowledgable (xluben). Will also post his reply.

By reading the 300 threads I've read so far lol...it def doesn't seem like compressor surge IMO either, although I think Keith just misunderstood my initial post/symptoms.

And I'm trying to get a solid answer on whether this is temp related. I seen a lot of posts about how colder temps can cause flutter...why though? Haven't seen an answer for that yet.

Now how do I tell if it's wastegate flutter or BPV flutter? how is it fixed "the right way" and why am I just experiencing it now? I'll have to see if it does it standing still just revving the engine. I doubt it but I'll try later. It only happens going into 4th so I doubt it'll do it just by revving it to boost.

I'm thinking mine may be temp related as this is the first time I've really gotten on it in colder temps. When I was tuned last Fall my engine barely had 1k plus an upgraded tune so I def took it easy on the car last year.

Could a leak in the BPV gasket be the cause if this?





Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#19 Old 10-15-2013, 09:23 AM
Moderator
 
mosc's Avatar
 
Join Date: Mar 2005
Location: Pennsylvania
Posts: 6,481
Images: 7
mosc is a helpful contributing member
Garage
I've heard of surge from stuck valves, particularly cheapo BOV's. I've heard of wastegate flutter. I have not heard of BPV flutter. I'm having a hard time picturing a BOV that has a weak enough spring to flutter but doesn't leak under WOT. Seems like it either can't open all the way and you get surge or it can't hold the pressure and it leaks.

Sorry that's not very helpful.

04 STi 16G powered lagless fun
04 WRX: SOLD
mosc is offline  
#20 Old 10-15-2013, 09:41 AM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
It's ok Mosc I still appreciate you chiming in. But me saying BPV flutter is just me using wrong terminology. I'm very green with anything turbo/ic/wastegate/bpv related. This is my first turbo'd car so this stuff is all totally new to me.

I just don't know where to start with diagnosing or fixing the problem...


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#21 Old 10-15-2013, 10:04 AM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
[update]

Here's the response I got from (xluben) off NASIOC. I responded to this reply with "is it norm to hear this flutter only going into 4th gear and only at high psi? Because most people experiencing flutter hear it at low psi and in every gear."

I'll share his response. I can't copy/paste his message so here's a screenshot.

Name:  ImageUploadedByAutoGuide1381849440.797834.jpg
Views: 138
Size:  130.7 KB

Does this seem like the right thing to do guys? I want to fix the problem, not put a bandaid over it. If this is the best fix then great. Just asking is all....


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#22 Old 10-15-2013, 12:55 PM
Moderator
 
mosc's Avatar
 
Join Date: Mar 2005
Location: Pennsylvania
Posts: 6,481
Images: 7
mosc is a helpful contributing member
Garage
It's very hard to diagnose this kind of thing over the internet. What the noise is and where it's coming from are pretty key. You typically hear your wastegate from your tailpipe and your bpv from your intake. Your description it sounds more like a wastegate issue than a BPV but that's just from words. I might listen to it and hear the BPV like you do. Usually that situation is the BPV unable to open and surging back into the turbo as Keith said.

Are there any power related symptoms or just sound related symptoms? If it's only a wastegate noise that's not a big deal. They're noisier than people think, especially at raised power levels in the higher gears where you're pushing a lot of exhaust.
psinuse likes this.

04 STi 16G powered lagless fun
04 WRX: SOLD
mosc is offline  
#23 Old 10-15-2013, 01:47 PM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
There's no performance loss no. There's a slight studder in the car when the flutter happens though.

I'll try an get it to do it while just revving it and standing outside and see if I can hear where the noise is coming from exactly.

I'll update you guys. Appreciate the help too. I know these types of things are extremely hard to diag over the internet...

And what if it were compressor surge. Where would I hear that coming from?


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#24 Old 10-15-2013, 02:19 PM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
Here's another reply from an extremely well known tuner in the NE. Also recommending swapping springs. In an earlier comment he mentioned that for my setup (told him in detail all my mods/tune numbers) he typically tunes with and recommends only the yellow spring, and never uses spacers at all. I have x2 shims in my BPV.

Name:  ImageUploadedByAutoGuide1381864667.854422.jpg
Views: 125
Size:  139.2 KB

So when I get home I'm going to...

Take it for a ride and see if I can duplicate the flutter in MA and in 60 degree whether, instead of NH and 40 degree weather.

Then I'm going to see if I can get it to do it while standing still at home and just revving it in neutral.

If it's still doing it here in MA then I know temp/alt had nothing to do with it and will try playing with spring/spacer combos.

I'll post my findings...


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#25 Old 10-15-2013, 03:01 PM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
And another well known tuner from the NE's opinion. Just figured I'd keep sharing people's responses. Hope some of this helps someone in the future. Yet again, mentioning springs...

Name:  ImageUploadedByAutoGuide1381867227.707179.jpg
Views: 124
Size:  139.4 KB


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#26 Old 10-15-2013, 03:05 PM
Moderator
 
mosc's Avatar
 
Join Date: Mar 2005
Location: Pennsylvania
Posts: 6,481
Images: 7
mosc is a helpful contributing member
Garage
The slight shudder in power is typical of a wastegate flutter common in near-capacity internally gated turbos. In other words, it's a power restriction when you feel it but not one that's going to hurt things. Also, your description of "70% throttle" screams wastegate to me, the car likes to keep exhaust flowing to the turbo but bypass SOME of it around, leading to dual streams and fluttering in between is your internally gated rather pissy wastegate wondering where all this extra exhaust gas is coming from when your engine is only 2.5L and why your right foot can't make up it's mind...

I don't really have any more info for you than that unfortunately. Good luck!
the RIOT act likes this.

04 STi 16G powered lagless fun
04 WRX: SOLD
mosc is offline  
#27 Old 10-15-2013, 03:10 PM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
Both of these tuners said doing any type of wastegate work isn't worth it. Do you guys agree with that? If the wastegate IS the problem with fluttering, why play with shims/springs to fix it? Do they not make wastegate mods to correct this? They mentioned porting the wastegate but said its a waste of money?.?. :/

Sorry if anything I'm saying is silly lol! I'm just the type to get to the root of a problem and replace whatever needs to be if anything at all...instead of just throwing bandaids on things (playing with springs/shims to fix flutter) unless that is the only real logical fix?.?.


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#28 Old 10-15-2013, 03:15 PM
Moderator
 
mosc's Avatar
 
Join Date: Mar 2005
Location: Pennsylvania
Posts: 6,481
Images: 7
mosc is a helpful contributing member
Garage
You said yourself it only happened in 4th, which is common for wastegate flutter. You have more load and thus more exhaust gas is generated. It's also not robbing very much and you rarely have your foot down in 4th for very long in peak boost (god I hope so on a public road).

Would an external wastegate buy you a couple HP? Probably. If you wanted to absolutely maximize a given turbo, you're not going to use it's internal gating. Certainly when you get into much larger turbos they don't even offer internal gating. Is it worth putting an external wastegate on your car? Probably not. Then again, I know people who love the straight cut exhaust sound that they can spice in when the car hits max boost and shoots out the dump tube.

I'm generally a fan of internal gating due to piping concerns. External is for people who can't avoid it.
the RIOT act likes this.

04 STi 16G powered lagless fun
04 WRX: SOLD
mosc is offline  
#29 Old 10-15-2013, 03:32 PM
Premium Member
 
the RIOT act's Avatar
 
Join Date: Dec 2012
Location: Massachusetts
Posts: 1,136
the RIOT act is more helpful than not
Garage
Well said! Thank you for the easy to understand explination Mosc.

And being WOT till redline is def something that isn't happening in 4th often lol! Maybe third...but not 4th 😜

In all seriousness I rarely drive my car aggressive enough to even notice the flutter I did over the weekend. Even when I'm doing a Mountain Run I'm still next to never at WOT.


Sent from AutoGuide.com App

Brandon - 13' SWP WRX Sedan
the RIOT act is offline  
#30 Old 10-15-2013, 03:41 PM
Moderator
 
mosc's Avatar
 
Join Date: Mar 2005
Location: Pennsylvania
Posts: 6,481
Images: 7
mosc is a helpful contributing member
Garage
Course, maybe it's your BPV seizing up and surging into your turbo and your wastegate is quite happy. #### if I know.

04 STi 16G powered lagless fun
04 WRX: SOLD
mosc is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On