# What wastegates



## Nigel-Power (Dec 16, 2009)

which wastegates make this sound/chatter, it's a distinct one

YouTube - 1000HP Top Secret Skyline


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## DrGtr (Jul 18, 2009)

HKS one i thing.


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## Noz (Jun 9, 2004)

Sounds to me like compressor stall, mine sounds like that with twin HKS 2540s and no BOV, but nowhere near as loud

HKS SSQV are a much higher pitched sound


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## Brains (Jul 6, 2010)

No wastegate makes that sound.
Blow-off valve is what you're looking for.

I think it sounds a bit to high-pitched for surging, but every car is different...

I'd also guess the HKS SSQV and i'll never understand why someone would want their car to sound like a sick bird.


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## Nigel-Power (Dec 16, 2009)

Brains said:


> No wastegate makes that sound.
> Blow-off valve is what you're looking for.
> 
> I think it sounds a bit to high-pitched for surging, but every car is different...
> ...


it's not the HKS SSQV far from it and I dont think any bov makes that sound, but wastegates probably. It must be some other make. 
As for who wants their car to sound like that, quite clearly Top Secret does by the looks of it and also Amuse in their Supra :nervous:

http://www.youtube.com/watch?v=aal9kG-EXeY

The Supra in this video sounds the same.


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## Asim R32GTR (Sep 24, 2003)

Its not the wastegate making that sound.

Its because he is running without a dumpvalve. Add a long aluminium pipe between the turbo and airfilter and you have that sound. 

Asim


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## SteveN (Aug 6, 2002)

Only reason people think SQVs etc make that noise is they are often so highly sprung they barely open/work, so you get the sound the same as you would if you run with no BOV at all.

Only reason people think wastegates do it is stupid TV programs and other media banging on about 'wastegate chatter' even though it doesnt exist.


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## Corsa1 (Sep 8, 2003)

SteveN said:


> Only reason people think SQVs etc make that noise is they are often so highly sprung they barely open/work, so you get the sound the same as you would if you run with no BOV at all.
> 
> Only reason people think wastegates do it is stupid TV programs and other media banging on about 'wastegate chatter' even though it doesnt exist.


And redline magazine LOL:thumbsup:


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## Noz (Jun 9, 2004)

Asim R32GTR said:


> Its not the wastegate making that sound.
> 
> Its because he is running without a dumpvalve. Add a long aluminium pipe between the turbo and airfilter and you have that sound.
> 
> Asim


Yup, although I get that sound with the standard rubber items between turbos & MAFs.

I think it sounds great


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## gtr.nation (Nov 26, 2009)

Here is another one of the cars that makes this kind of sound.

YouTube - Skyline R34 GT-R V-Spec 610HP in Stockholm


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## gtr.nation (Nov 26, 2009)

Asim R32GTR said:


> Its not the wastegate making that sound.
> 
> Its because he is running without a dumpvalve. Add a long aluminium pipe between the turbo and airfilter and you have that sound.
> 
> Asim


In other words no waste gate, no BOV . Any exact name ?


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## Noz (Jun 9, 2004)

gtr.nation said:


> In other words no waste gate, no BOV . Any exact name ?


"Running with no BOV" 

On my 200SX S13, it sounds like a pigeon. So on the SXOC it's called "the pigeon"


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## Asim R32GTR (Sep 24, 2003)

gtr.nation said:


> In other words no waste gate, no BOV . Any exact name ?


The sound is comming from the compressor side of the turbo.
A wastegate is located on the turbine side of the turbo, and cannot make this sound. 

You need a wastegate. 

Dumpvalve you can run without.


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## gtr.nation (Nov 26, 2009)

Noz said:


> "Running with no BOV"
> 
> On my 200SX S13, it sounds like a pigeon. So on the SXOC it's called "the pigeon"


So then is it compressor surge?


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## Asim R32GTR (Sep 24, 2003)

gtr.nation said:


> So then is it compressor surge?


It can be compared to compressor surge, but not directly the same thing. 

Turbo is producing more air then what is beeing used, thereby it fills the pipes, and excess air comes out the inlet of the turbo.


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## Noz (Jun 9, 2004)

gtr.nation said:


> So then is it compressor surge?


Sorry, meant "stall", not "surge" in my first post, it was late/early :runaway:

Surge occurs during spool due to a compressor housing too large for the engine.

YouTube - True Compressor Surge


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## Noz (Jun 9, 2004)

What's happening in the case of the Top Secret Skyline, is that when the throttle plate is closed, the build up of pressure which would be exited via a BOV (accompanied by a tssssss/whoooooooosh etc) is instead forced back through the system and through the turbine blades. Some cars flutter due to the pressure wave traveling back & forth rapidly, some cars sound like the Top Secret Skyline. 

Don't know the spec of the Skyline, but mine sounds exactly the same (albeit quieter) with twin 2540s, so I'm guessing it's a twin set-up


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## Nigel-Power (Dec 16, 2009)

Notice on half throttle the pigeon sound is repetitive like a vibrating bouncing sound. Mine sounds very similar. there needs to be a fair bit of boost though to hear it that loud. I was thinking maybe its the screamer pipes


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## Cris (Sep 17, 2007)

More likely to be compressor chatter.

I have a memory of someone saying you can get the same effect with a stiff spring on the bov. Will chatter before the stiffer spring dumps the pressure as normal.


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## gtr.nation (Nov 26, 2009)

Asim R32GTR said:


> It can be compared to compressor surge, but not directly the same thing.
> 
> Turbo is producing more air then what is beeing used, thereby it fills the pipes, and excess air comes out the inlet of the turbo.


Asim bro, this air which is coming out is actually harmful for the compressor blades. But one thing i dont understand is such high powered cars running without a BOV ? even the best makes of turbo will fall apart due to that ..


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## Noz (Jun 9, 2004)

gtr.nation said:


> Asim bro, this air which is coming out is actually harmful for the compressor blades. But one thing i dont understand is such high powered cars running without a BOV ? even the best makes of turbo will fall apart due to that ..


I ran a cheap T70 & a GReddy TD06-20G at 1.7 bar for ages without any issues with no BOV. I've not run a BOV on any of my cars for years as I've not found one piece of concrete evidence to suggest that compressor chatter/stall/pigeon will cause a turbo to fall apart. OEM recircs are manufactured to help supress noise, aftermarket ones are made 'cos they make nice sounds (yet screw with the MAF readings (where applicable) and introduce another place for leaks to occur)


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## Nigel-Power (Dec 16, 2009)

right peeps, been trying it out today and this evening  mine sounds exactly as the the ones in the videos courtesy of HKS Twin GT2835r Turbos, no airfilters... and its freaking loud too, nothing new thoug I was just wondering what is it exactly that causes that pigeon sound  
Tried it on half throttle too to see the repetitive pigeon sound bouncing and it feels great I must say. Whatever it is that makes that chatter its there under the bonnet, made me feel like making a sensible video


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## Noz (Jun 9, 2004)

It's this fella:


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## NITO (Nov 19, 2003)

My old supra used to make the exact same sound as this GTR. It was the HKS GT wastegate, which is a much nicer sound to the GTII wastegate. Mine had this and an HKS bov but I've had plenty of these bovs on other cars which don't sound like that. Its wastegate chatter!!


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## Nigel-Power (Dec 16, 2009)

now that's funny :chuckle: good find that one :thumbsup:


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## Nigel-Power (Dec 16, 2009)

NITO said:


> My old supra used to make the exact same sound as this GTR. It was the HKS GT wastegate, which is a much nicer sound to the GTII wastegate. Mine had this and an HKS bov but I've had plenty of these bovs on other cars which don't sound like that. Its wastegate chatter!!


It must be, I have HKS wastegats in mine so that must be it then


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## Noz (Jun 9, 2004)

Nigel-Power said:


> now that's funny :chuckle: good find that one :thumbsup:


My extreme Photoshop skills :runaway:


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## matty32 (Dec 18, 2005)

id never go back to BOVs after externals


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## Noz (Jun 9, 2004)

Seriously, wastegates don't chatter when you let off the gas pedal.

Wastegate - Wikipedia, the free encyclopedia


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## NITO (Nov 19, 2003)

I beg to differ...you have positive pressure acting on the diaphragm from the compressor pressurised line and a spring on the other side to keep the plunger closed when you lift off, when your developing say 1 bar there's a fair amount of boost in the system, when you back off partially there'll be a drop of pressure on the compressor line which means loads less resistance on the diaphragm/ spring which will then bounce against its own spring tension as it releases and then shuts after venting excess pressure happening rapidly like a valve spring juggling pressures, causing wastegate chatter. Have a look at a diagram of an external wastegate. most have two ports also so you can have pressure acting on each side of the diaphragm.

I've had compressor surge and its nothing like this, its awful, the whole car surges, not a flutter or chatter like this, feels more like fuel surge that shakes the whole car.

regards
Nito


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## Noz (Jun 9, 2004)

Yeah, compressor surge is totally different to this, that's down to the engine not being able to consume air at a quick enough rate when mated to a turbocharger with a compressor too large for the application. That WILL goose your turbo quickly! 

The wastegate rapidly opening/closing happens under partial throttle, but in the case of the Top Secret Skyline, it's due to the throttle plate being shut when fully letting off the accelerator and the resultant built-up boost pressure wave having nowhere to go but back towards the turbos. Compressor stall, pigeon, flutter etc.

At least I think that's right


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## NITO (Nov 19, 2003)

Again, I don't buy the throttle plate theory because my supra was an auto and used to make this chatter on full chat gearchanges where the throttle was wide open, but on auto changing gears there was a resultant drop of boost on upchanges as it found the next gear.

Cheers
Nito


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## Noz (Jun 9, 2004)

Who knows then! My car with twin HKS 2540s & actuators makes _exactly_ the same noise when letting off fully. I ran my S13 with both a knock-off 60mm ext. wastegate and a GReddy ext. wastegate and never got this sound, although I was running with a screamer pipe so it was all a bit noisy!

My Rover Coupe Turbo makes a ridiculously loud fluttering sound, as did my Fiat Coupe Turbo and all the other single turbo cars I've had.


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## NITO (Nov 19, 2003)

I've only had two externally gated cars, both HKS single turbos, the Supra had the original HKS GT wastegate and sounded like that TS car, the second was my Nur with the purple HKS GT II wastegate and it didn't sound like the Supra! So I put it down to the original GT wastegate, I wonder who made it for HKS, shame they don't still make it.

Regards
Nito


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## Marlon88 (Sep 20, 2008)

That sound is Air passing trough the compressor blades. Wastegates do not make that sound. A car that does that noise its either has no BOV, or the BOV has a hard spring/set hard from the adjustable screw, or car has too much boost and the BOV is small and not flowing enough air out meaning not letting all the air out so part exits from the BOV and remaining air exiting from the compressor side.


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## R.I.P.S NZ (May 7, 2004)

^^^^^agreed.


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## Nigel-Power (Dec 16, 2009)

Right so as confirmed by Rob, it seems to be the air passing through the compressor blades that produce that sound. not the BOV or screamer pipes or wastegates as such, but the harder sprung BOV or smaller wastegates per higher boost pressure causes the air to be pushed through the compressor blades and the result is the pigeon chatter.


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## Noz (Jun 9, 2004)

Pretty much what I said in the 3rd post. No wait... _Exactly _what I said


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## NITO (Nov 19, 2003)

I stand corrected, so the explanation for my Supra was the bov setup with stong spring tension. 

Curious that an internally gated Subaru with the same bov on its strongest setting running more boost doesn't do the same, is this purely down to volume of air generated by larger engines. The supra had a single bov whereas my skyline had twins which may explain why the gtr didn't do it.

Sorry Noz!! Cheers Rob and Marlon.

Cheers
Nito


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