When i take off hard, ie above 2200 rpm, as in a freeway entrance, but have to slow down abruptly and let go off the pedal completely, i hear this screeching sound. It doesnt occur if i let the pedal off slowly. Is it the turbo, or the tranny, or ???

 

Most likely you are hearing the turbo "de-spool". I am betting you hear it more since it is sort of a mid engine rig. It just means you are spooling with authority.

Pretty sweet motorhome, BTW. I typically steer clear of them, but would love to have like like yours.

 

That is turbo bark and it is very bad for the turbo so try not to do it.

 

This rarely happens, only when really brave stupid people get in my way despite of the loud jet engine sound and my rig's size, forcing me to slow down abruptly.

Capt., thanks for the compliments.

 

A screeching sound is different than the "choo choo choo" or "woosh woosh woosh" of turbo bark. If you are barking the turbo you will see the boost gauge wildly fluttering in time with the noise.

Your are possibly approaching turbo bark in those situations. It seems to be more pronounced in heavy vehicles with an auto. A sloppy converter will make it even more likely.

Watch some you tube vids of turned up 5spd trucks rowing gears, you will hear the screeching sound. P pumps do it a little worse because of the way they defuel faster.

 

CaptainChrysler described it well. It's pretty normal if it's like the sound at 0:12 in this video:


All that's happening in that case is the turbo spooling down rapidly. However, if it's the "choo choo choo" noise accompanied by boost gauge flutter, it's generally not good for the turbo.

 

You can hear it better in this video.



Its not a bad on the turbo as long as it isn't making the sneezing noise. I have noticed the factory h1c turbos with no mwe slot seem to make this noise. When I changed my compressor side to a wh1c housing my truck stopped making that noise.

 

Mine did that with the straight pipe n my dads 95 auto did that with the straight pipe as well.

 

The stock h1c turbos will do that. I noticed my baby h1c did that with a 4" straight pipe after fueling hard and backing out to shift. I wouldn't worry about it unless you hear the sounds of barking as described above.