Originally Posted by flyn2high

I my Skymaster T-33 I have a fairly loud high pitch whistle at high throttle settings. I've been told this could be very dangerous.

Here is a video that you can sort of hear the whistle on take off (at 1:10 min) and when I accelerate to do a roll (at 2:30 min). For some reason the whistle is a bit muted in the video. As I remember it was a lot louder in person.

https://www.youtube.com/watch?v=CHUgUCrm07c&t=428s

I've been told that it could be due to the exhaust tube bell-mouth being too far from the back of the turbine and that hot exhaust was recirculating back to the intake.

I opened it back up to see what I could do. Please see the attached photo. The exhaust tube bell-mouth is actually slightly overlapping the rear of the turbine by about 1/8 inch. I am now wondering if the bi-pass is too tight a fit on the turbine. At the front of the bi-pass where it necks down it is 1/4" clearance. At the widest point it is 1/2" clearance. Should I remove the bi-pass and give it a try?

The settings are all set to the default for diesel fuel except I reduced the max rpm to 114,000 rpm so as not to overpower the plane.

Please let me know what you think,