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Old 08-08-2008, 10:53 AM   #1
2subiesinyard
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Default New downpipe, new noises...concerned.

I installed an Invidia V2 DP last Sunday, used my Cobb APV2 and reflashed my base map to the stage 2 93 oct. (cat back is from a 05 STi with 2.5 id) .I've been driving it for a week now, and I'm loving everything except the noise. Maybe I'm just not used to it. Due to the fact that that it is a tubular DP I'm hearing all of the turbo noise. But I only hear it at lower rpm's and when my boost gauge is on the vacuum side (10 in/vac). It sounds like the exhaust gasses causing turbulence against the vanes of the turbo.

I checked all of the exhaust mating points...turbo to DP, DP to center pipe and CP to axel back and they are all tight and leak free.

Is it normal to hear all of this turbulence while the exhaust gasses start to spool up the turbo? Once the turbo gets going and the boost picks up to the positive side the swirling turbulence noises dissapate.
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Old 08-08-2008, 10:58 AM   #2
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You're probably just hearing the wastegate flutter. It kinda sounds like a helicopter right? It's perfectly normal.
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Old 08-08-2008, 10:59 AM   #3
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^^ That's a great analogy, and I think that is in fact what he's hearing.
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Old 08-08-2008, 11:03 AM   #4
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yeah thats what it is man. im having issues with it as well and have been since i instaled my invidia v3 on my02. it does sounds kinda goofy though ha. im pretty positive that ive got a leak right off of the turbo but cant find it as the bolts are all tight. im eventually going to just get some rtv and put a seal around it and clean it up and see if that takes care of it...but im lazy
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Old 08-08-2008, 11:05 AM   #5
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Just step on the gas and the noise goes away
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Old 08-08-2008, 11:38 AM   #6
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Quote:
Originally Posted by resideinva View Post
yeah thats what it is man. im having issues with it as well and have been since i instaled my invidia v3 on my02. it does sounds kinda goofy though ha. im pretty positive that ive got a leak right off of the turbo but cant find it as the bolts are all tight. im eventually going to just get some rtv and put a seal around it and clean it up and see if that takes care of it...but im lazy
It's not an "issue". It's perfectly normal. If you're concerned about an exhaust leak at the turbo, pull off the heat shield and look for black soot on it. If there isn't any, then there's more than likely nothing wrong. Also, I would advise not to put RTV on your exhaust. It'll likely just burn off and possibly catch something else on fire.
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Old 08-08-2008, 12:21 PM   #7
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Quote:
Originally Posted by ammo0000 View Post
It's not an "issue". It's perfectly normal. If you're concerned about an exhaust leak at the turbo, pull off the heat shield and look for black soot on it. If there isn't any, then there's more than likely nothing wrong. Also, I would advise not to put RTV on your exhaust. It'll likely just burn off and possibly catch something else on fire.
I checked for a leak at all flanges. No soot ...all bolts/nuts tight. I took my time putting the DP on, about 3 hrs in the driveway. The wastgate flutter explaination sounds like what I hear. After I lift off the gas pedal it "bleeds off", but it's as loud as a normal conversation.

Should I be hearing wastegate flutter when my wastegate duty cycles are 0???

and I agree, no rtv at the flange...NO WAY!
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Old 08-08-2008, 01:20 PM   #8
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check out youtube and watch some in car pulls of stage 2 cars... see if your car sounds similar.
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Old 08-08-2008, 01:43 PM   #9
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^^^^^ I will, good idea thanks.
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Old 08-08-2008, 01:50 PM   #10
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Whooshing air noise is normal with a big free flowing exhaust. My 4" TurboXS downpipe makes crazy whooshing and tea kettle whistling noises - its pretty cool
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Old 08-08-2008, 02:54 PM   #11
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Quote:
Originally Posted by subenerd View Post
Whooshing air noise is normal with a big free flowing exhaust. My 4" TurboXS downpipe makes crazy whooshing and tea kettle whistling noises - its pretty cool
Same downpipe here, sounds pretty much like this. Now if it sounds like "angry bees in a tin can" it might be an exhaust leak after the DP.

Last edited by Ranyart; 08-08-2008 at 02:54 PM. Reason: typo
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Old 08-08-2008, 04:24 PM   #12
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Quote:
Originally Posted by subenerd View Post
Whooshing air noise is normal with a big free flowing exhaust. My 4" TurboXS downpipe makes crazy whooshing and tea kettle whistling noises - its pretty cool
Same here. Wastegate flutter is what you're hearing OP. It's normal, I got used to it and don't even really notice it anymore. Every now and than a friend will get in the car with me and say that something's not right because of the noise....
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Old 08-08-2008, 04:28 PM   #13
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Wastegate flutter. Just like everyone else has already said. Search for it, and read up. We've all been there.
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Old 08-08-2008, 04:30 PM   #14
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I can't hear it over the screaming from the passenger seat anyways
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Old 08-08-2008, 09:41 PM   #15
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Quote:
Originally Posted by Mavrik View Post
Just step on the gas and the noise goes away
I like how this man thinks
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Old 08-08-2008, 09:43 PM   #16
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if you want to quiet down the noise/flutter get some heat wrap for the downpipe,night + day difference,also helps keep the heat away from the tmic.
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Old 08-08-2008, 11:23 PM   #17
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Why is this a problem. I'd love to be able to hear my turbo and wastegate flutter. It sounds so badass.
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Old 08-09-2008, 06:15 AM   #18
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I checked out some youtube videos and between that and all of the posters in this thread I know now it's the wastegate flutter. Thanks all, this puts my mind at ease.
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Old 06-29-2009, 03:26 AM   #19
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I'm having the same issue with this "badass" air/turbulence going on with my Stage 2 wrx. It's been scaring the crap out of me. I followed the instructions word for word/step by step. Everything seems tight and in place. The only thing I noticed was that the downpipe to Catback gasket was visible and when I had installed the donut gasket, it was very loose around the diameter of the Downpipe ring. (Would this cause any exhaust leakage?) It looks similar to this person's setup:
See how the flanges of the pipings aren't lined up?
But now that everyone says the sound is normal, I'm thinking about putting the springed bolts back on because I'm sure they allow a certain amount of give when used.
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Old 06-29-2009, 03:34 AM   #20
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Its such a unique noise. Ive never heard it on any other car but a subaru...
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Old 06-29-2009, 04:31 AM   #21
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I've been hearing 50/50 answers about all of this. 50% say: "It's normal and enjoy it" while the other half say: Exhaust leak/Boost Creepage/BPV Loose. Meh.
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Old 06-29-2009, 04:34 AM   #22
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STI's don't have 2.5" exhaust.

It's 60mm. 2.36".
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Old 06-29-2009, 10:55 AM   #23
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Quote:
Originally Posted by Mdub View Post
Why is this a problem. I'd love to be able to hear my turbo and wastegate flutter. It sounds so badass.
I'm not sure why you would want to hear wastegate flutter...

Wastegate flutter is when the wastegate goes back and forth from open to closed under part throttle low boost conditions, it has a ticking sound that can be mistaken for an exhaust leak or misfire.

here is a thread on how to reduce wastegate flutter
http://forums.nasioc.com/forums/show...lutter+arm+fix

and another thread with a pic
http://www.scoobymods.com/wastegate_...tegate+flutter
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Old 06-29-2009, 12:30 PM   #24
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Thanks T-37. I'll check out those links
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Old 06-29-2009, 12:59 PM   #25
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If you used the gasket that came with the DP or the CB then I'd ditch it for the OEM gasket. The gaskets that have a comb like center are horrendous. Mine actually tore and fell out of my newly mated UP to my turbo. I went and bought an OEM and it never had another problem.
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