Riddle Me This

[Cm452]

Took two friends out to show them what my car had to offer in terms of acceleration. On entrance ramp to highway, up hill, I booted it in 2nd(60% throttle). It spun the tires easily, but then this whistle/whine/metallic high-pitched ringing noise came on progressively louder and steadier as revs and boost did.
In the heat of the moment, I thought it might have been noisy PWM drivers from the ECU, which can, on occasion, be heard or some part vibrating against something. I also asked a friend to check that the lines from the water/methanol weren't kinked and that the reservoir had fluid in it ( about 1/3rd tank left). He confirmed this. So I gave it ~70% throttle in 3rd and 4th, only to again have the noise come back. So, we high-tailed it back to his garage where we found nothing, on the computer from the logs or mechanical.
Two hours later I drove home and tried to replicate the sound; nada, even at WOT. The next day, I had one friend get in the car and we tried to get the noise to come back, again, no noise.
No one could pin point where the noise was coming from. Wasn't the back seat where the w/m pump&tank are, nor did it seem to be coming from the turbo.

I don't think it was the clutch slipping and making noise either, as the revs matched the speed.

Anyone have any ideas?
It kinda sounded like this, but lower and less whistly/airy.
https://www.youtube.com/watch?v=UEvtLlikdc4
Thanks,
-Cm

[Aikmanson]

Interesting, it was metallic sounding? Unless you can replicate I would not worry. My 900 made all kind of noises then the next day they would be gone, just the attitude of these cars. If it comes back take a look at the pulleys/WP/turbo/BCV. My BCV likes to make a rap-rap sound at like 1500rpm in vacuum.

[srp]

What's the suspension setup on your car? Lowered? Long shot, but maybe something to do with the extra weight plus the ass end squatting when you go WOT.

[bogan]

Wheel bearing .......*Guessing*

[Cm452]

So effing random, but this is a better approximation of the tone..kinda reedy, but such that once at sufficient frequency it produced a whine. It started out reedy too...
###vbulletinsuckspleasecopyandpastelinkhttp://www.youtube.com/watch?v=ug64rZESK-Y&t=0m20s
-Cm
Edit: So, I made a link that goes right to the time in question in the ridiculous video I posted, so there is no fiddling. You need to post the entire http----etc,etc. It links to the 20 second mark of the video. Vbulletin just embeds the video but doesn't include my fancy address coding to omit the first half of the video...\rant

[Cm452]

Originally Posted by srp

What's the suspension setup on your car? Lowered? Long shot, but maybe something to do with the extra weight plus the ass end squatting when you go WOT.

Yes, it is lowered on the Eibachs, and to Bogan; it has new wheel bearings in the front and the rear ones seemed fine 2k miles ago when I last checked.
-Cm

[vt9000cse]

Awesome boost 1.92 Bar?

[Cm452]

Originally Posted by vt9000cse

Awesome boost 1.92 Bar?

you think it was a turbo/pressure related sound?
-Cm

[Tweek's Turbos]

How recently have you done your idler pulley's and whatnot?

[Cm452]

Originally Posted by Tweek's Turbos

How recently have you done your idler pulley's and whatnot?

Never...just replaced the belt and everything seemed to spin freely and without noise. When I say just replaced the belt I mean like <200mi ago.
The consensus is that those in the car (including myself) believed the noise to emanate from the passenger footwell area. This is not entirely helpful, as the glovebox is gone, which tends to funnel noises from the engine bay to the cabin.
-Cm

[SPG-GASM]

My viggen will make almost a whistle/whine under full boost in 2nd and sometimes 3rd gear. I think it's air coming from the throttle body to upper pipe connection. If I were you, I would do a boost leak test on the car.

[bogan]

Did you have your cabin fan on?

My fan makes strange noises from time to time ...... Then goes away

[mike9000aero]

Had a similar noise turned out my gasket to the turbo/manifold was leaking slightly

[Tweek's Turbos]

If it is one of those pulleys, it will let you know for sure soon enough.I actually was able to cross ref. my original replacement thread on SC with when I had it fail 4 or so years later.

[comtrang]

Sounds like a pulley

[Cm452]

Originally Posted by bogan

Did you have your cabin fan on?

My fan makes strange noises from time to time ...... Then goes away

YES! I DID! Might just be the culprit...it does make screeching-whistling-dieing chipmunk/bird sounds from time to time. I will investigate the pulleys.... you guys ROCK

-Cm