Ok so what is turbo bark, as ive heard it called ?? I know what the sound is but what is the turbo actually doing ? Cause my truck tends to do it sometimes, and just wandering if its normal, if its preventable?, or if its my driving doing it ?? I've heard its very hard on turbos and cause severe damage ? And my turbo is new and wanting to address the problem before i regret it.

 

Its called compressor surge and its the force of air coming back through the intake at your turbo's compressor wheel. It causes the wheel to shudder back and forth and that's what you're hearing as a noise. It eventually wears down the bearing and seal leading to complete turbo failure (i.e. compressor wheel meeting the side of the turbine housing or destroying the oil seal. This is why most turboed cars have a blow off valve. The engines vacuum opens the valve on the charge pipe the allow excess pressure to be be blown off instead of slowly destroying the turbo.

 

Bark is easy to control, just don't let off the accelerator rapidly while at more than 10 psi boost.

 

So would a blow off valve help ? And do they make one big enough for big diesel turbos ? at 45 psi ??

 

Barking the turbo is stalling the rotating assembly. When you are at full bore, you have pressure across the turbine, driving the compressor, building pressure as well. Let off the throttle, you no longer have the pressure to drive the turbine, and the built up pressure in the intake side wants to escape the easiest way. It rapidly slows or stops the whole thing and flows out the suction side of the compressor. Thats a lot of momentum to absorb, and it doesn't 'brake' on the turbine side, so that wants to continue at the previous speed. Leads to shaft breakage.

Since diesels do not throttle air, the pressure differential across the butterfly in a gasser that the blow off would use as a signal doesn't exist. BD has an electronic version of one for what was $600. Not sure if they are available for the 12v's. It was called the BD Turbo Guard.