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Vacuum line on intake pipe...connects to?

KLMOTORSPORTS

Well-Known Member
Awesome, thanks!! Another quick question...I’m not running any of the EVAP on my engine (using stand alone engine wiring harness)...know where the bottom vacuum hose on the SC By Pass would be connected to? I would assume off the intake?

Thanks!!
2DCEFAA4-DF3A-45F4-A492-960F4C2F8B3D.jpeg
 

baustin

Well-Known Member
here's what the stock Cobalt setup was for me:
10148


If I'm understanding the parts correctly, the evap solenoid is mounted on a bracket with the boost controller solenoid just to the driver's side (names are probably slightly off). In this image you can see the route the line you're asking about runs to the boost controller. The evap system has a harder vinyl or plastic line that runs to the front side of the supercharger. Not sure what happens if you remove the boost controller but I'm starting with just the evap solenoid gone.
 

askiles

Well-Known Member
Awesome, thanks!! Another quick question...I’m not running any of the EVAP on my engine (using stand alone engine wiring harness)...know where the bottom vacuum hose on the SC By Pass would be connected to? I would assume off the intake?

Thanks!!View attachment 10142
It goes to the little boost controller electrical module thinga-ma-jiggy, to the driver's side of the valve cover. It was next to the evap stuff. You still need that to control the boost.
 

Ross

Goblin Guru
The MAF sensor needs laminar airflow, so reducing the rubber to aluminum overlap will allow a longer intake, and help.
The intake is near the limit of being too short.
Also those hose clamps need to be tighter than I thought, as mine failed the intake leak smoke test.
Easy fix, but it didn't idle right until i fixed it.
 
Hey all, my intake pipe doesn't have a bung for the connection to the valve cover. Do i need to drill? Sidewall seems thin for that to be stable. The charge pipe has more of a bung.
 

Attachments

Murcielago311

Well-Known Member
I ordered a drill and tap to add the port, but then decided to do what most do and exclude crank case breather line all together and install a breather filter on the valve cover.

It really cleans up the rear of the valve cover visually and I saw no adverse performance.

Will probably swap out the filter every season, but when I had the valve cover baffles out the two before the breather were pretty clean.
 

Attachments

JBINTX

Goblin Guru
I would suggest you keep the port and connect it to the intake. The line is part of the vacuum system designed to keep vacuum in the valve cover. A filter will vent, but will not help with the vacuum.
Many have indeed deleted it - maybe without major negative effects. If you have a turbo, the vacuum problem in the valve cover gets more complex.

There is more in-depth discussion here:
https://dfkitcar.com/forum/index.php?threads/oil-separator.1596/

My kit included the pipe without the port as well. DF replaced it free of charge.
 

Fozda

Well-Known Member
I would suggest you keep the port and connect it to the intake. The line is part of the vacuum system designed to keep vacuum in the valve cover. A filter will vent, but will not help with the vacuum.
Many have indeed deleted it - maybe without major negative effects. If you have a turbo, the vacuum problem in the valve cover gets more complex.

There is more in-depth discussion here:
https://dfkitcar.com/forum/index.php?threads/oil-separator.1596/

My kit included the pipe without the port as well. DF replaced it free of charge.
There's no vacuum in the intake pipe between the filter and the turbo inlet. I believe you're thinking of the PCV system.
 

Zoom Zoom

Well-Known Member
I ordered a drill and tap to add the port, but then decided to do what most do and exclude crank case breather line all together and install a breather filter on the valve cover.

It really cleans up the rear of the valve cover visually and I saw no adverse performance.

Will probably swap out the filter every season, but when I had the valve cover baffles out the two before the breather were pretty clean.
You have a very nice looking home, Love all the property, You are the MAN
 

Desert Sasqwatch

Goblin Guru
There's no vacuum in the intake pipe between the filter and the turbo inlet. I believe you're thinking of the PCV system.
In normal operation - excluding a catch can or oil separator:
Airflow through the intake piping does create minor vacuum at the air filter - Bernoulli's theorem - the vacuum is what pulls air through the filter element. The connection of the valve cover to the intake pipe is to allow some air into the crankcase when certain operating conditions require not exceeding a specific vacuum limit created by the rest of the vacuum system.
The intake is under vacuum when not in boost - that is what the PVC that is mounted inside the intake manifold controls and pulls crankcase vacuum when the throttle is lifted. In boost, the PVC prevents pressure from entering the crankcase port from the intake manifold. When there is boost, the valve cover port that feeds into the turbo inlet pulls the air from the crankcase to maintain a vacuum on the crankcase pressure. It is possible that both could pull excessive vacuum and that is what the filtered air feed is from the intake tube before the turbo.
That's what the connection from the intake tube to the valve cover is for, to keep the vacuum level in check, so it is an important part of the vacuum system for a stock setup.
 

JBINTX

Goblin Guru
In normal operation - excluding a catch can or oil separator:
Airflow through the intake piping does create minor vacuum at the air filter - Bernoulli's theorem - the vacuum is what pulls air through the filter element. The connection of the valve cover to the intake pipe is to allow some air into the crankcase when certain operating conditions require not exceeding a specific vacuum limit created by the rest of the vacuum system.
The intake is under vacuum when not in boost - that is what the PVC that is mounted inside the intake manifold controls and pulls crankcase vacuum when the throttle is lifted. In boost, the PVC prevents pressure from entering the crankcase port from the intake manifold. When there is boost, the valve cover port that feeds into the turbo inlet pulls the air from the crankcase to maintain a vacuum on the crankcase pressure. It is possible that both could pull excessive vacuum and that is what the filtered air feed is from the intake tube before the turbo.
That's what the connection from the intake tube to the valve cover is for, to keep the vacuum level in check, so it is an important part of the vacuum system for a stock setup.
Well said
 
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