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turbo backpressure.

1013 Views 6 Replies 6 Participants Last post by  KATOOM
I did the stock airbox delete and put one of those spectre cone filters on and now when I hold a steady psi or let off the throttle after building a high psi real fast...high psi being from 18 to 32. A buddy of mine said this is turbo back pressure. Good? Bad? How do I fix it? Could the filter be to small?
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if your saying your hearing a noise when you let off real fast, that's known as "turbo bark" and whats happening is you have all this exhaust energy driving the turbo. That in turn has the compressor wheel compressing air and sending it through the intercooler and then into the engine. When you let off the throttle quickly you no longer have the exhaust energy driving the turbo, but you have all that pressurized air on the compressor side. It is looking for the easiest way out. The easiest way out isn't to continue on through the intercooler and to the engine, but to try and come back through the turbo. This causes the compressor wheel to slow dramatically which can hurt either the wheel or the shaft if its done over and over.
 

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im not sure if a cone filter would cause it unless it has a low CFM rating, the BHAF mod is well known around here, but then again these filters are rated for ~680cfm.


The stock airbox is rated for more, but the input hole for the stock airbox is rated much lower and causes the restriction.
 

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How do I fix the bark
Stop letting out of the go pedal so fast. :rof


Sorry, Couldn't resist. It takes a bit of practice to "ease-out" of the go pedal, but it'll help your turbo last. Practice, practice and practice some more.:blues:
 

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if your saying your hearing a noise when you let off real fast, that's known as "turbo bark" and whats happening is you have all this exhaust energy driving the turbo. That in turn has the compressor wheel compressing air and sending it through the intercooler and then into the engine. When you let off the throttle quickly you no longer have the exhaust energy driving the turbo, but you have all that pressurized air on the compressor side. It is looking for the easiest way out. The easiest way out isn't to continue on through the intercooler and to the engine, but to try and come back through the turbo. This causes the compressor wheel to slow dramatically which can hurt either the wheel or the shaft if its done over and over.
This is exactly right IF you're post is about barking. If you're simply hearing a howling whirling sound upon letting off the throttle at higher boost pressures then you're fine. Barking is bad and can cause the turbo shaft to break which is why guys who push real high boost have been known to set up pop off valves like turbo gas engines.
 
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