So I finally got a chance to replace that turbo oil inlet line with SS line and new fittings. Went on a test run around the block, everything is fine except this wooshing sound from the turbo when i let off the gas....I was wondering if it's a problem with the wastegate.....It's all stock, and I was going like 10mph.

Any ideas? things I could check or need to replace?

Thanks guys

 

Did a little research online, and found this on TurboGarrett.com:

"What is causing my turbo to sound like a sewing machine's whistle?
The "sewing machine whistle" is a distinct cyclic noise cause by unstable compressor operating conditions known as compressor surge. This aerodynamic instability is the most noticeable during a rapid lift of the throttle, following operation at full boost. "


so it's compressor surge......and how do I fix that?

 

I thought a bov was supposed to fight compressor surge, but I might be wrong.

 

What the hell does a sewing machine whistle sound like?

 

Did some more research:

on http://en.wikipedia.org/wiki/Blowoff_valve

"Purpose of Relief and Blow Off Valves

Blowoff valves are used to prevent compressor surge. Compressor surge is a phenomenon that occurs when lifting off the throttle of a turbocharged car (with a non-existent or faulty bypass valve). When the throttle plate on a turbocharged engine running boost closes, high pressure in the intake system has nowhere to go. It is forced to travel back to the turbocharger in the form of a pressure wave. This results in the wheel rapidly decreasing speed and stalling. The driver will notice a fluttering air sound. In extreme cases the compressor wheel will stop completely or even go backwards. Compressor surge is very hard on the bearings in the turbocharger and can significantly decrease its lifespan. In addition, the now slower moving compressor wheel takes longer to spool (speed up) when throttle is applied. This is known as turbo lag.

With the implementation of either a bypass valve or a blowoff valve the pressurized air escapes, allowing the turbo to continue spinning. This allows the turbocharger to have less turbo lag when power is demanded next."