Could someone explain why it happens , happened to me yesterday and doesn,t sound good , I know its from letting off the throtle too quickly and maybe too much pressure built up in turbo maybe??? Does it cause any damage sure doesn"t sound good . thanks

 

Someone may add to this or correct it but I am thinking the turbo bark is the compressor wheel momentarily stalling from excess pressure (more pressure in the system than the engine can use at that moment and more than the turbo can overcome). I dont think it is bad for the engine just the turbo. It puts a lot of stress on the turbo shaft. I think the hx35 shafts are fairly stout for the size of the turbo, but that is not to say they can take it indefinitely or that they cant/wont break.

 

This happens when you are getting on the throttle and then very quickly let out of it. Your turbo is spinning very fast and the engine is taking the air so all is well, but when you take the fuel away from your engine, the engine does not take the air anymore(or as much as it was a slpit second ago), causing it to and slow down the turbo charger rpm dramatically and very quickly. this causes the turbo to surge and that is what you hear, the air flowing backwards through the turbo., then back the right way, then backwards, etc... Atleast that is how I understaned it...

 

Yup! BarryG is right also.
The noise is actually a compressor stall...caused by the air pressure suddenly reversing direction back onto the turbo compressor blades. Produces loss of laminar flow over blades. Noise is actually air flow disturbance (like popping a bag full of air). By-product is rapid deceleration of the spinning turbo (can be from 100,000+ rpm to zero)...with corresponding reverse twist stress on the turbo shaft!
It is not good for any turbo.. some handle it better than others. It should be avoided when possible.

-Removing the Silencer ring will reduce barking in many turbos....allowing the reversed air to flow by the blades instead of through them. Note: no turbo has ever been designed with silencer ring...Dodge added that for noise control.
-Less rapid throttle reductions, whenever possible, will eliminate it.

RJ

 

not recommended but you can really scare the S out of someone riding shotgun or someone you are driving beside...