Engine/Transmission (1994 - 1998) What exactly is TURBO BARK???

[cluckmaster]

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?

 

[RSP]

You just described it yourself.

 

[cluckmaster]

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?

 

[SEmerson]

no any turbo will bark. A pop off valve will not stop it. It is a rush of pressure back through the turbo. Easy on and easy off the pedal works.

 

[PKemp]

Bigger won't help. Just increases the inertia of the wheel making it easier to snap the shaft. You need one with a larger diameter main shaft like a Phat Shaft 62 or something like that. Diesel Performance parts also has a turbo relief valve that will also help. All it takes is $$$.

On the other hand better application of the foot type appendage would relieve the stress on your wallet. A busted turbo shaft could mean miscelaneous loose broken parts unleashed into the intercooler, intake manifold and cylinder head. Very hard small pieces of metal now trying to be compressed between the piston crown, valves and cylinder head. Hmmmmm what would go first? People say, well those pieces wouldn't make it thru the intercooler! Ever roll dice in the dark, for lots of money? Its a scarry experience. Maybe you win, maybe you lose. Cheaper to be careful, save the money for a "big power" buy later on, say perhaps "twins". From what I see you've got too much money invested now to "dally" with an old turbo if thats the original.

 

[Forrest Nearing]

no any turbo will bark. A pop off valve will not stop it. It is a rush of pressure back through the turbo. Easy on and easy off the pedal works.

a pop-off valve won't help, but a blow-off valve will

 

[cluckmaster]

Bigger won't help. Just increases the inertia of the wheel making it easier to snap the shaft. You need one with a larger diameter main shaft like a Phat Shaft 62 or something like that. Diesel Performance parts also has a turbo relief valve that will also help. All it takes is $$$.

On the other hand better application of the foot type appendage would relieve the stress on your wallet. A busted turbo shaft could mean miscelaneous loose broken parts unleashed into the intercooler, intake manifold and cylinder head. Very hard small pieces of metal now trying to be compressed between the piston crown, valves and cylinder head. Hmmmmm what would go first? People say, well those pieces wouldn't make it thru the intercooler! Ever roll dice in the dark, for lots of money? Its a scarry experience. Maybe you win, maybe you lose. Cheaper to be careful, save the money for a "big power" buy later on, say perhaps "twins". From what I see you've got too much money invested now to "dally" with an old turbo if thats the original.

Yup... still the original. Looking at maybe a 62/12 PS now that can be used as the top turbo of a twin setup later.



Forrest- how does the blow-off valve work?

 

[Forrest Nearing]

Forrest- how does the blow-off valve work?

when you let off the throttle at boost, it vents that pressure to the atmosphere instead of back through the turbo's compressor housing. a pop-off valve simply vents pressure above a set level. blow-offs are throttle actuated (or vac actuated on a gasser)