I have this sound, ppl call it the wastegate chatter, chirping, compressor surge.
http://members.aol.com/s132fortysx/bov.mp3
What actually is it?
It make sound like this between shift, along with BOV when in boost, is it compressor surge?
Its kinda wicked though.
what sound is this?? WRC??
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silviamaniac
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I believe thats from a wastegate. Many race setups have the waste gate opening as late as possible, but also as fast as possible. So it fluctuates between open and closed as the boost rises and falls.
Wastegates that are more timid (such as the stock on most cars) open gradually and avoid the extra noise, but they boost slightly slower since they leak out pressure before full boost is reached.
In racing you do anything to get a few more hp and a quicker spool. Ive heard ths sound on M. Orido's Ridox Supra which has a much larger turbo, and puts out about 600hp. (its in one or two of the best motoring vids)
Its not compressor surge which Im sure many people will claim. Comp surge flutters as well but is very rough, uncontrolled, and tapers off gradually.
I could be wrong and its from a recirc valve... but just know its because the settings are very agressive and tuned a certain way.
Wastegates that are more timid (such as the stock on most cars) open gradually and avoid the extra noise, but they boost slightly slower since they leak out pressure before full boost is reached.
In racing you do anything to get a few more hp and a quicker spool. Ive heard ths sound on M. Orido's Ridox Supra which has a much larger turbo, and puts out about 600hp. (its in one or two of the best motoring vids)
Its not compressor surge which Im sure many people will claim. Comp surge flutters as well but is very rough, uncontrolled, and tapers off gradually.
I could be wrong and its from a recirc valve... but just know its because the settings are very agressive and tuned a certain way.
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C-Kwik
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Hard to say for sure without seeing the inputs, but it sounds like a BOV to me as it sounded like the noise was occurring when he was backing off the throttle? Was this from a video of a car drifting? The only reason, I can not be sure of the sound is because if it was the BOV, he was on and off the throttle quite a bit.
My HKS bypass valve makes a similar type of sound. So did the one on my friend's Supra. I've been trying to put my finger on why some flutter and why some make one long release soound. I've been speculating it has to do with where the wastegate signal is taken from. Both mine and my friend's cars wastegates sourced their signal from the manifold. Another friend of mine had the long sound, but I am not positive where his wastegate received it's signal from, and he no longer has the car so I can't check.
My HKS bypass valve makes a similar type of sound. So did the one on my friend's Supra. I've been trying to put my finger on why some flutter and why some make one long release soound. I've been speculating it has to do with where the wastegate signal is taken from. Both mine and my friend's cars wastegates sourced their signal from the manifold. Another friend of mine had the long sound, but I am not positive where his wastegate received it's signal from, and he no longer has the car so I can't check.
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Pornflakes
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silviamaniac
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p00t wrote:I believe thats from a wastegate. Many race setups have the waste gate opening as late as possible, but also as fast as possible. So it fluctuates between open and closed as the boost rises and falls.
Wastegates that are more timid (such as the stock on most cars) open gradually and avoid the extra noise, but they boost slightly slower since they leak out pressure before full boost is reached.
In racing you do anything to get a few more hp and a quicker spool. Ive heard ths sound on M. Orido's Ridox Supra which has a much larger turbo, and puts out about 600hp. (its in one or two of the best motoring vids)
Its not compressor surge which Im sure many people will claim. Comp surge flutters as well but is very rough, uncontrolled, and tapers off gradually.
I could be wrong and its from a recirc valve... but just know its because the settings are very agressive and tuned a certain way.
I hope i have whatever you think it is, but mine is a tial 38mm and SSQV running at max 4psi now to break in.
My ssqv is definately different from this, i hav 2 sound basically, when i let off throttle, i will get this sound even if i dun hav boost, if i boost it up, i get bov + this wrc sound.
I guess its compressor surge, but i try to figure the sound source, it kinda "sounds" where my wastegate dump located... confused
C-Kwik wrote:I've been trying to put my finger on why some flutter and why some make one long release soound. I've been speculating it has to do with where the wastegate signal is taken from.
I have the Blitz DD and it flutters under low boost and up to 6PSI. My friend has an Eclipse with the HKS SSQ and it flutters under low boost. In both cases, as the boost gets higher and thus the amount of air released gets higher, the sound turns into a screech which I believe to be a more rapid fluctuation.
Taken from blitz-na.com: "DD (Dual Drive) for maximum response (small port for low boost + larger port for high boost)"
So I think my blow off switches between the two ports thus creating the flutter sound and I'm pretty sure that's what the SSQ does too.
I don't think it is compressor surge since I disconnected the recirc line from my BOV and I felt the air fluctuating out and thus the sound has to come from there.
The other BOVs, the ones that make a continuos release sound probably have a single chamber (or whatever mechanism they use) and thus the air release doesn't fluctuate.
Hope this is what you were refering to.
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C-Kwik
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My HKS bypass is not anythin fancy. It's nothing more than a bypass. None of the fance SSQ stuff. So that can't be the cause of the fluttering.
And to those that think the sound is surge, I highly doubt it. It sounded a lot like the noises were being made when backing off the throttle. And wastegates don't make that kind of noise. When my dump pipe was divorced, it opened smoothly and progressively.
One reason I think the fluttering occurs with a wastegate signal off the manifold is that the wastegate will close as soon as the throttle is closed. That means all exhaust energy is driven through the turbine. The compressor won't slow down as quickly as it will with the signal off the compressor outlet. With the signal feeding off the compressor outlet, it will see pressure still and keep the wastegate open which will slow down the compressor quicker. But what I think occurs is that the IAV allows enough air in to the manifold. The motor ingests this in cycles. As the IAV doesn't flow enough to keep manifold pressure constant. It's purely speculation at this point. I'm still trying to confirm if using a signal at the compressor ever make the same fluttering sound.
And to those that think the sound is surge, I highly doubt it. It sounded a lot like the noises were being made when backing off the throttle. And wastegates don't make that kind of noise. When my dump pipe was divorced, it opened smoothly and progressively.
One reason I think the fluttering occurs with a wastegate signal off the manifold is that the wastegate will close as soon as the throttle is closed. That means all exhaust energy is driven through the turbine. The compressor won't slow down as quickly as it will with the signal off the compressor outlet. With the signal feeding off the compressor outlet, it will see pressure still and keep the wastegate open which will slow down the compressor quicker. But what I think occurs is that the IAV allows enough air in to the manifold. The motor ingests this in cycles. As the IAV doesn't flow enough to keep manifold pressure constant. It's purely speculation at this point. I'm still trying to confirm if using a signal at the compressor ever make the same fluttering sound.
