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Old 10 August 2006, 03:02 PM
  #61  
logiclee
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Originally Posted by Mike Rainbird
I disagree. The standard boost pressures that these turbos run from the factory, is not sufficent to cause the shock loads you mention. IMO, it is PURELY for noise suppression. I have NEVER EVER seen a turbo fail without a dumpvalve, running factory boost.
Mike, it would be very hard to quantify I agree, you could never get two cars to do exactly the same 100k miles over five years with the same abuse/conditions/usage/heatup/cool down cycles. Using a DV may mean the turbo last 100k miles and without it it will fail at 80k miles but who knows. It would be very hard to say that running with no DV had caused premature failure.
What is certain is running a turbine in a stall condition adds strain and fatigue, whether this takes 1000miles off it's life or 30000miles off it's life is very hard to quantify and depends on the specific use and design.
I would almost certainly say that most manufacturers fit a DV for relaibility reasons as well as noise suppresion though.

Cheers
Lee
Old 10 August 2006, 03:33 PM
  #62  
Adam Hybrid
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Originally Posted by GC8
It shows; now run along.
Fine here thanks, since you've been severely owned i noticed a distinct shortening of your posts. Where's this wealth of knowledge gone

Old 10 August 2006, 05:09 PM
  #63  
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If I remember it correctly its VolksWagen that actually lists the item as a noise suppressor. Check with your local VW spares department if you dont believe me.
Old 10 August 2006, 09:48 PM
  #64  
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I have read quite a few types of posts where people ask how to make their Scoob sound like a WRC ie the chirps etc.. As some one has already mentioned it is not an external wastegate on them either but surge, My old pulsar with a KN cone and a VTA used to sound pretty similar sounded kinda cool.
Any way so how do you block off the DV then? I take it you just put a blanking plate on the intercooler, do you make said item or order it from some where, I also take it you would have to have a cone filter on to amplyfy the noise?
Old 10 August 2006, 10:05 PM
  #65  
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Just to really clear things up found this, a vid of a Scoob with an external wastegate.
http://www.youtube.com/watch?v=8dMC1rvf9IQ
Old 10 August 2006, 10:27 PM
  #66  
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Well that was helpful - it sounds just like any other scoob!
Old 20 December 2006, 07:19 PM
  #67  
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Originally Posted by Bat-Fink

WRC cars run ALS as well

A normal re-circ DV does not make any noise as you know.



A VTA one does make a ptshhh noise.


Nissan Silvia S13 CA18DET Aftermarket Blow-off Valve (BOV) - Google Video



But if you blank off the dv hole,when you close the throttle what happens is the air hits the now closed throttle plate and travels back towards the compressor wheel on the turbo.



The air gets chopped up by the spinning compressor wheel and thus makes a very cool noise.



This is called comp stall or comp surge.



NOT! wastegate chatter.



A example of comp surge.

http://video.google.co.uk/videoplay?...4393&q=chatter





Another good example of running without a DV,even tho it says it's got a DV it ain't

YouTube - S15 BOV



Dan.
Just to clear things up.

Last edited by Bat-Fink; 20 December 2006 at 07:24 PM.
Old 20 December 2006, 07:21 PM
  #68  
ukdave
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Yer ive regularly been at events where ppl have commented on comp surge hmmm not saying theyre wrong buts lets face it most ppl know it as wastegate chatter
Old 20 December 2006, 07:23 PM
  #69  
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Originally Posted by Rannoch
Well that was helpful - it sounds just like any other scoob!
I agree lol
Old 20 December 2006, 07:26 PM
  #70  
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Originally Posted by ukdave
Yer ive regularly been at events where ppl have commented on comp surge hmmm not saying theyre wrong buts lets face it most ppl know it as wastegate chatter
Agree to a degree mate but it isn't wastegate chatter.
Old 20 December 2006, 07:29 PM
  #71  
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lol i know but its what its mainly referred to as pmsl cant believe we`ve opened this old thread about it-im blaming u
Old 20 December 2006, 07:30 PM
  #72  
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Originally Posted by ukdave
lol i know but its what its mainly referred to as pmsl cant believe we`ve opened this old thread about it-im blaming u
Old 21 December 2006, 11:20 AM
  #73  
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Originally Posted by Bat-Fink
Agree to a degree mate but it isn't wastegate chatter.
PMSL @ Batfink

You tell em G!
Old 21 December 2006, 12:48 PM
  #74  
LG John
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Logic Check

I used to get that chattering noise when lifting at medium boost and medium engine speeds in my MY99. I was using a Forge VTA dumpvalve at the time and running 1.2bar of boost on the TD04. Lifting from full boost and/or full chat would produce the 'Tisssssssh' we expect of a VTA. Lifting at very low boost might produce a little hiss but mid-way would give you that chatter.

Based on what I've read in this thread it is my understanding that:

* When I was closing the throttle at high boost the excess air was backing up and blowing off out the DV into the atmosphere. No problems there (aside from borewash and other related issues with VTA on scooby).

* When I was lifting off at medium boost the air was backing up but wasn't at a sufficient pressure to overcome the DV spring and so would travel back and stall the turbo, hence the chatter.

^^^ are both of those accurate? Is it fair to say the chatter could have been reduced/eliminated by a weaker DV spring? Would that chatter have been harmful to the turbo?
Old 21 December 2006, 12:51 PM
  #75  
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Ah havnie got a Scooby ! (well, sort of ).
Old 21 December 2006, 12:52 PM
  #76  
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Originally Posted by Saxo Boy
Logic Check

I used to get that chattering noise when lifting at medium boost and medium engine speeds in my MY99. I was using a Forge VTA dumpvalve at the time and running 1.2bar of boost on the TD04. Lifting from full boost and/or full chat would produce the 'Tisssssssh' we expect of a VTA. Lifting at very low boost might produce a little hiss but mid-way would give you that chatter.

Based on what I've read in this thread it is my understanding that:

* When I was closing the throttle at high boost the excess air was backing up and blowing off out the DV into the atmosphere. No problems there (aside from borewash and other related issues with VTA on scooby).

* When I was lifting off at medium boost the air was backing up but wasn't at a sufficient pressure to overcome the DV spring and so would travel back and stall the turbo, hence the chatter.

^^^ are both of those accurate? Is it fair to say the chatter could have been reduced/eliminated by a weaker DV spring? Would that chatter have been harmful to the turbo?
Sounds about right mate TBH.

Not sure on turbo strength as you never hear on here about how strong the turbos are against it.
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