Recirculating Blowoff Valve recommendations

Davidljones88

Well-Known Member
I'm having a hard time finding a recirculating BOV/BYPASS valve. Do you have any suggestions?

I considered a bullet bov that releases to atmosphere and recirculates, but the site:
https://www.hahnracecraft.com/products/cobalt-tc-billet-blow-off-valve
doesn't allow payment right now.

I have a stock LDK 2.0 with zzp ecu, and Z54 turbo, and an f23 trans. The previous owner installed a cheap $200 k04 and it's making the car smoke and leak oil. It has a lot of flutter.
 

Desert Sasqwatch

Goblin Guru
Who was the builder? It will help to answer if the build log can be reviewed (if one was created).

Not certain a new or specific type of turbo can cause an engine to smoke - unless there is an internal seal leak allowing oil/coolant into the charge air. This smoking condition could also be caused from a bad head gasket, piston rings, valve seals, or PCV - has this been diagnosed to rule these out? And you state an oil leak, where at?

The K04 boost pressure relief valve will 'flutter' during operation to prevent boost over pressure during throttle let-off. Can you define 'a lot of flutter'? Not sure that jumping into a new turbo and installing a BOV will solve the smoking issue if there is already an oil leak and the source of the smoke - oil or antifreeze - is not defined.
 

Gtstorey

Goblin Guru
I think most of the people that have upgraded on here are still running the oem control. It sounds like the k04 was either over boosting or the oem control wasn’t working properly.
 

Ross

Goblin Guru
Who was the builder? It will help to answer if the build log can be reviewed (if one was created).

Not certain a new or specific type of turbo can cause an engine to smoke - unless there is an internal seal leak allowing oil/coolant into the charge air. This smoking condition could also be caused from a bad head gasket, piston rings, valve seals, or PCV - has this been diagnosed to rule these out? And you state an oil leak, where at?

The K04 boost pressure relief valve will 'flutter' during operation to prevent boost over pressure during throttle let-off. Can you define 'a lot of flutter'? Not sure that jumping into a new turbo and installing a BOV will solve the smoking issue if there is already an oil leak and the source of the smoke - oil or antifreeze - is not defined.
GeorgeM built car 214, and sold it to David. No build log.
 

Waterdriver

Goblin Guru
I'm having a hard time finding a recirculating BOV/BYPASS valve. Do you have any suggestions?

I considered a bullet bov that releases to atmosphere and recirculates, but the site:
https://www.hahnracecraft.com/products/cobalt-tc-billet-blow-off-valve
doesn't allow payment right now.

I have a stock LDK 2.0 with zzp ecu, and Z54 turbo, and an f23 trans. The previous owner installed a cheap $200 k04 and it's making the car smoke and leak oil. It has a lot of flutter.
Here is a link to a recirculating system blow off valve by Forge. Used this on my Audi TT. https://www.forgemotorsport.com/Turbo_Recirculation_Valve--product--756.html

Is the fluttering effect on acceleration or decel?
 

comegetjoe

Goblin Guru
I went with a FORGE valve. Give it a look, i enjoyed the way it sounds.

 
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escapepilot

Goblin Guru
Fortunately this forum is loaded with knowledgeable and helpful people. I’m sure the community will help you get it sorted out. Where are you located? Maybe someone is close enough they could give it look.
 

Waterdriver

Goblin Guru
Deceleration. I definitely want to get rid of the back pressure as Google says it'll harm the turbo over time. Are they generally universal or do they really need to be specific to each car?
That fluttering is called compressor surge which is not good for a turbo.
Comegetjoe listed the Forge part specific for the 2.0 turbo Cobalts.
Not sure on your build, but if the donor was 08-10 Cobalt, I'd stick with what Joe listed or OEM.
I would first check the vacuum line that attaches to the diverter valve running to the control solenoid and the the manifold for any cracks or holes and replace.
The solenoid can be suspect as well. The needle and seat can get dirty and prevent it from operating properly. You can remove it and clean it out with carb cleaner. While spraying into one of the ports you need to power the valve on and off to help flush out and remove all debris. I saw a bit of gunk come out of mine on my TT. Looked like bits of rubber from the vacuum line breaking down internally.
After cleaning the diverter then worked like it should. No more fluttering and instant power/boost on upshifts.
 
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