ALH TDI - New 3 inch Exhaust - Now mysterious "blow off vlave" noise ?? help please

JacobLyons · Feb 2, 2008

ALH TDI - *New* 3 inch Exhaust - Now mysterious "blow off vlave" noise ?? help please

So I just got 3inch DP back put on and every time I shift I hear like a "blow off valve" swoosh of air; what is it? It only happens when i let off the throttle when comming out of boost.. and it sounds like some one is slamming on squeeky brakes.. It's coming from inside the engine bay. It feels completely normal, and I have no lose in power. I want to make sure it's not a problem I should be concerned with. Any one have an idea?

Thank You,

Jake

REDNECKDZL · Feb 2, 2008

that's just the turbo releasing pressure, same thing happened to my car when I did cat back straight pipe.

It's a great sound, I can be found driving up and down main street just going on and coming off the go pedal, never gets boring

B.L.T · Feb 2, 2008

My favorite was doing it right beside a wall of a building, sounds like a jet taking off then the nice blow off sound coming off of boost.

Drive threw people hate me.

mojogoes · Feb 3, 2008

And it sounds better than any bov.......lol.

dogdots · Feb 3, 2008

My 3" sounds just like a jet at idle and up to about 1800rpm when the frequency range gets above my hearing ability.

I love it and all the ricers are jealous !!!

JacobLyons · Feb 3, 2008

Thanks for the feedback guys; I appreciate it. I wanted to make sure that sound was normal before I got excited. It does sound f**king amazing though

LurkerMike · Feb 3, 2008

where did you get the DP?

buckweat diesel · Feb 3, 2008

i love that sound
but its gone now that i have a vnt 20 stg3

LNXGUY · Feb 3, 2008

Mike, I think the DP is stock, I think he removed the cat and ran 3" all the way back.

Street Toys · Feb 3, 2008

buckweat diesel said:
i love that sound
but its gone now that i have a vnt 20 stg3

You want me to make you a 5' downpipe?

LOL!

johnnloki · Feb 3, 2008

buckweat diesel said:
vnt 20 stg3

Oh boo-hoo! Cry me a river!

oldpoopie · Feb 3, 2008

Street Toys said:
You want me to make you a 5' downpipe? LOL!

if you can make it fit? LOL.

up_pup · Feb 6, 2008

Mine makes the same sound too. Kerma down pipe to 2 1/2 inside oem cat, then 2 1/2 out to daul 2 1/2's.have alligator tune plus dp tuning box on it.

Braga_Dub · Feb 6, 2008

The "WOOO" noise vanished with my 17

I just got a 1.8T like "sneeze" through the intake now.
Makes me want to put on the 15 again haha

LurkerMike · Feb 6, 2008

I'm thinking the OEM exhaust and IC setup is designed to suppress as much noise as possible... even at the expense of being restrictive.

Once you go with better flowing exhaust and/or intake and IC plumbing, you allow the turbo to "sing" it's tune more audibly.

But I'm also thinking that no two turbo's sound exactly the same.

Yes, there will be a difference from one size turbo to the next as the wheels and internal volumes that shape the sound are different.

But I'm also thinking that there is much variance from one turbo of the same size to the next in terms of sound emissions.

Does that seem to be the case based on what has generally been experienced?

02DslPwr · Feb 6, 2008

LurkerMike said:
I'm thinking the OEM exhaust and IC setup is designed to suppress as much noise as possible... even at the expense of being restrictive.

Once you go with better flowing exhaust and/or intake and IC plumbing, you allow the turbo to "sing" it's tune more audibly.

But I'm also thinking that no two turbo's sound exactly the same.

Yes, there will be a difference from one size turbo to the next as the wheels and internal volumes that shape the sound are different.

But I'm also thinking that there is much variance from one turbo of the same size to the next in terms of sound emissions.

Does that seem to be the case based on what has generally been experienced?

I went through two turbos on my MR2, three turbos on my Supra and I'm on my second with the Jetta. the two on the MR2 were stock sized turbos and they sounded the same. On the Supra, the larger the turbo got, the less high-pitch wine there was from the turbo. I think this is due to it spinning slower than a smaller turbo. I would think the larger the hot side gets, the lower the pitch gets.

Robert

spooner miller · Feb 6, 2008

Hey, I wanna do a turbo back large exhaust to get that jet engine sound at idle, but will i lose that with a 17/22 turbo upgrade??? I hope not!!!

woofie2 · Feb 6, 2008

spooner miller said:
Hey, I wanna do a turbo back large exhaust to get that jet engine sound at idle, but will i lose that with a 17/22 turbo upgrade??? I hope not!!!

Nope, IBW (IndigoBlueWagon Peter from TDIparts.com) has that setup and his wagon sounded Fly at Old Navy's last fall. His car sounded sweet at idle.

I took my muffler off, and love to go out and stir the rice, the local kids will get whiplash when I do a full boost, low speed, throttle blip (3/4 throttle to 1500-1800 RPMs (second or third gear) touch the clutch) and the happy Piezzzzzaaaa comes from the turbo.

Fix_Until_Broke · Feb 7, 2008

spooner miller said:
Hey, I wanna do a turbo back large exhaust to get that jet engine sound at idle, but will i lose that with a 17/22 turbo upgrade??? I hope not!!!

The VNT-15 with "large" exhaust will give the jet engine sound at idle (see videos in my signature), the 17/22 loses all of that. Sounds more like an angry hiss from a cat. No videos of this setup yet, but I can swing through Dubuque next weekend (15th) on my way to/from Iowa if you want to take a listen. PM me if you want to.

shortysclimbin · Feb 7, 2008

I never thought of it but it sounds like we tuned the pipe to the Res. frequency of the turbo charger making the pipe act like a horn on a trumpet. If you want a vnt20 or another turbo to make that same sound you are going to have a hard time. The larger turbo will have a different note to play through a different size trumpet....

Wow, anyone interested in playing tdi tunes with different pipes and turbos?

ilrocketboy · Feb 7, 2008

I had the same noise, although it has seemed to have gone away now. I noticed somewhat of a reduction in the noise when I added my PP520's. In my mind this shouldn't make a difference, but maybe it does. Should I be concerned about loosing the noise?

Steve

LurkerMike · Feb 7, 2008

shortysclimbin said:
I never thought of it but it sounds like we tuned the pipe to the Res. frequency of the turbo charger making the pipe act like a horn on a trumpet. If you want a vnt20 or another turbo to make that same sound you are going to have a hard time. The larger turbo will have a different note to play through a different size trumpet....

Wow, anyone interested in playing tdi tunes with different pipes and turbos?

A series of step-ups in pipe diameter can be more easily tuned for sound quality than a single pipe size system by moving the placement of the steps...

spooner miller · Feb 7, 2008

Would it matter if i take out the flex pipe with a 4" straight?? I'll pry just cut it in front of the flex pipe and run straight 4 all the way back with a nice diesel truck stainless tip.

Fix_Until_Broke · Feb 7, 2008

I would definately leave a flex pipe of some sort in the exhaust as close to the engine as practical.

4" through the "hole" above the steering rack is very cozy and will most likely always be rattling on something.

ALH TDI - *New* 3 inch Exhaust - Now mysterious "blow off vlave" noise ?? help please

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ALH TDI - New 3 inch Exhaust - Now mysterious "blow off vlave" noise ?? help please