Just wondering what everyone is referring to when talking about turbo bark. What is it, what does it sound like, etc.

I've got a Scotty II that's pulling air through a hole in the cowl as well as the fender, and sometimes when I get into it hard and then let off all of the sudden, it sounds like the passenger side dash is getting sucked through the intake in loud, short, fast bursts. Used to scare the crap put of me, but I figured it was the intake housing sucking against the metal cowl. Any ideas?

 

thats turbo bark. when you have the turbo spooled throwing lots of air into the engine and you let off real quick and the airflow stops quickly, the weight and rotation of the turbo wants to keep spinning which causes some weird things to happen with in the turbo housings because the airflow has slowed down so much.

 

Just did some reading in the archives and think I've got it. Saw several people mention blow off valves. Anyone using them?

Also, I see it's harmful to the turbo (ie could break the shaft)? Looking at switching turbos soon, so will a bigger turbo eliminate the problem?

 

I don't think its harmful to the turbo in any way... but someone correct me if I'm wrong.

 

Compressor surge or stall unloads then loads the compressor impeller blades each surge cycle. This can lead to low cycle fatigue failures of compressor impeller blades or the turbocharger shaft. Thrust loading also changes dramatically every surge cycle, so surge is beating on the thrust bearing.

Smaller turbos are generally more forgiving of surge, but the large industrial engine turbochargers (and centrifugal compressors in general) can be destroyed by surge in a relatively short time. So, I wouldn't say it isn't harmful - just that it may take more cycles until problems arise with the smaller turbos.

Rusty

 

My 61/12 barks like crazy. I have to back out of it really slow.

 

I've had my stock turbo bark a couple of times. First time was when i was doing donuts in a field of snow. The second times was doing donuts in a parking lot and I let off quickly. But during normal driving, etc i always let of slowly.

 

Even if you get a after market turbo it will still bark have to back off the little pedal easy. i didnt realy get it bad on stock HX35w but when i put my 62/14 in it would do it real easy.