[CurtisEmery]

Turbo bark is when you start operating the turbo on the fringe of it's surge line. There is a point when any turbine basically "stalls" for lack of a better term which makes some interesting noises. The correct way to fix it is to slow the turbo down with either a wastegate or variable vanes on the compressor side. Opening a BOV would do the oposite, it would basically unload the turbo and allow it to spin to the moon.......which would not be a good thing.

We really need to find the compressor map for our stock turbo's it's much easier to explain this if you can put hard numbers to it. I haven't had any luck finding one.

This is an incorrect assumption. Comparing the uses of a BOV for a Diesel and a Gasser makes no sense, the uses are entirely different. We are trying to relieve boost, were as the gassers are trying to maintain boost during upshifts. When a BOV opens it actually slows the turbo rpms down. Remember the turbo is still compressing air when the BOV opens. Just with out drive pressure to maintain compressor rpm as it nornally would under light to full throttle conditions. In my opinion this is a good idea on a diesel just expensive. On a side note: Engineered Diesel makes a drive pressure actuated boost relief valve that is about half the price of the BD unit.

 

[LMM_Guy]

Ok sorry guys, I'm new to the term "bark" I thought you were talking about turbo surge, which is what happens when you operate the turbo outside of it's surge line. The situation you guys are talking about, lifting out of the throttle, is different but basically the same situation which is getting your pressure ratio too far apart between the hot and cold sides of the turbo. In a diesel you are removing the exhaust energy by shutting off the fuel, which causes the cold side to "bark". On a gas engine you keep the exhaust energy somewhat but increase the intake pressure by shutting the throttle body.......which still creates too much intake to exhaust pressure ratio.

I didn't realize that the BOV was maintaining a preset pressure in the intake tract. On a gas job the BOV blows off all intake charge.

 

[turbo65joe]

hey hey now hes getting it. we are just trying to save our turbo shafts. thats all.

Joe

 

[TIM Z]

Great info/ discussion guys.

 

[Silverado6600]

So in summary, a BOV on a Diesel is a good thing? I'm still racking my brain on Diesels. I was always a gas guy until recently. I have SEEN THE LIGHT!

 

[duramaxsandwich]

So in summary, a BOV on a Diesel is a good thing? I'm still racking my brain on Diesels. I was always a gas guy until recently. I have SEEN THE LIGHT!

yes.
BOV (no Barking) = Good
no BOV (Barking a lot) = Bad

 

[Silverado6600]

I looked at some of these BOVs. How easy is it to install them, what's involved, and how do I know what size to get?

 

[CurtisEmery]

The Engineered Diesel one would be quite simple. You need to weld the bung onto the intercooler tube(pre-intercooler). And drill and tap a hole in your exhaust manifold for the drive pressure line. Not sure about sizing thou. I would think that there would be no such think as too large???

 

[Blackhatch]

Good discussion.

Is bark and issue with the stock turbo on these trucks?

 

[MMLMM]

2 things...

BOV is good on a diesel, it wont spin to the moon because it opens when you lift up. Also there are ways to operate with drive pressure.


AND

LMMs do have a throttle plate...........

 

[Blackhatch]

Seems like that engineered diesel kit is a nice simple compromise.

Any benefit to venting the boost back to the exhaust/drive side of the turbo?