I got this strange thing going on for 5 months now...
Installed an STI engine into my Classic, complete with VF34 turbo.
After running in, the turbo developed a strange whistling sound, only when cruising off boost. It's like a muted jet engine, goes up and down with the revs.
As soon as I make boost, the turbo works 100 %, no excessive sounds or strange boost behaviour.

It's just that whistling sound under 3k revs and below 40 mph, with no boost.

I was told that VF series roller/ball bearing turbo's will do that, but I know from other STI owners, that they don't have that noise...

???

 

not had this on mine, although its newer than that, where did you source the turbo from?

 

Turbo was brand new, as was the complete engine (without manifold/exhaust)

Strange thing is that I drive the car so for almost 5 months, so if it was really a problem with bearings/shaft or similar, it defenitely must have blown.
(Already went 3 times to the 'Ring, together almost 20 laps, and 2 weeks ago drove 500 km's trough Europe, mostly flatout...)

 

My VF34 has done it since new, been told it's ok... some do it some don't.

 

First I tought that the "whistling" I'm talking about was an interference in my radio... It sound exactly the same, a very slight sound...

 

Yeah mine does that, always wondered what it was. The car was mapped and everthing checked and working fine.

 

I can park up get out the car and stand at the front door as the turbo stops whining.

 

mine does it but only with the CAIK, not with the normal airbox.

In my opinion it sounds sexual. I just love it.

Jet engine noise at low rev's, to full chat, full boost tischh.