Manual Boost Controller Vacuum Lines

[TzReddy]

I had a question on best place to run vacuum lines from manual boost controller. On my stock intake manifold I actually tapped the bottom port of the intake manifold on the driver side of intake where would normally got to driver side of valve cover. I run breathers so I capped it originally. Was wondering if that is an ok place to run for vacuum with the manual boost controller? I have a C&L intake manifold with the new build and looking for ideal places for all my vacuum lines. I just know when I have been researching they say for the boost controller is to run it separately vs into a t or a vacuum block with a bunch of other vacuum lines. I could be completely wrong and only looking for info.

 

[RED09GT]

I used that port as my signal to my blow off valve so it should be good for a boost controller. I run my electronic boost controller off a T from the vacuum line on the fuel rail and have had no issues whatsoever.

 

[702GT]

I had a question on best place to run vacuum lines from manual boost controller. On my stock intake manifold I actually tapped the bottom port of the intake manifold on the driver side of intake where would normally got to driver side of valve cover. I run breathers so I capped it originally. Was wondering if that is an ok place to run for vacuum with the manual boost controller? I have a C&L intake manifold with the new build and looking for ideal places for all my vacuum lines. I just know when I have been researching they say for the boost controller is to run it separately vs into a t or a vacuum block with a bunch of other vacuum lines. I could be completely wrong and only looking for info.

I'm a little lost. Why do you need vacuum for a MBC? I had a MBC on my wastegated procharger, and I tapped into the boost pipe directly, pre IC, for the purest boost reading. Plugged that into the inlet side of the MBC, and then plugged the outlet line right into the wastegate.

A MBC, or even electric boost controller, should need no vacuum sample at all. It doesn't care about vacuum, only boost. If you don't have the means to tap the charge piping (which is only a drill bit, fitting, and some sealant) then you should be able to use any line connected to the intake manifold that is unregulated. I do suggest not using the line that connects to your FRPS, as when the MBC functions it will cause a drop in air volume as it sends pressure to the wastegate.

Otherwise I my suggestion stands, tap the charge pipe pre-IC, to MBC, to WG. Adjust up from there.

 

[JeremyH]

Indeed, boost controllers call for a pressure only source, ie pre throttle.

 

[RED09GT]

After thinking about it, it is just the electronic display and control unit that I have”T'd" off from a post throttle source, the solenoid get's it source from just after the compressor and is fed to the wastegate. You definitely don't want to use the one you describe for a manual boost controller.

 

[702GT]

After thinking about it, it is just the electronic display and control unit that I have”T'd" off from a post throttle source, the solenoid get's it source from just after the compressor and is fed to the wastegate. You definitely don't want to use the one you describe for a manual boost controller.

He could use the post-TB source and be just fine, the vacuum won't negatively effect the MBC, he just needs to beware what line he taps into. As I stated earlier, if you draw from a line that uses vacuum/pressure for a sensor, you could negatively affect that sensor by drawing air away from it.

To be the most accurate though, you want to draw are from the compressor or charge pipe itself, pre-IC.

 

[05stroker]

I run all my vacuum lines off of a block with a single line going to the intake. I have ran a electronic boost controler this way with no issues. You just need to make sure the line feeding the block is large enough to support what you have connected to the block ports. Am I missing something here?

 

[05stroker]

To be the most accurate though, you want to draw are from the compressor or charge pipe itself, pre-IC.

I have heard this before but never understood it. What is the reason for reading boost pre I/C?

 

[RED09GT]

I have heard this before but never understood it. What is the reason for reading boost pre I/C?

Other than reading it somewhere, I am not really sure.

With a turbo and an electronic controller, you would want the boost controller to know and control whatever boost you are seeing at the manifold. As for the solenoid that controls the wastegate, maybe it can react faster if it is tapped into the compressor?

At the end of the day, it was the manual that came with my boost controller that dictated how I set it up. It has worked as advertised getting the controller signal from post throttle and the solenoid connection off the compressor.

OP, what does the manual from the boost controller tell you to do?

 

[JeremyH]

I run all my vacuum lines off of a block with a single line going to the intake. I have ran a electronic boost controler this way with no issues. You just need to make sure the line feeding the block is large enough to support what you have connected to the block ports. Am I missing something here?

I have heard this before but never understood it. What is the reason for reading boost pre I/C?

Yes Billy, all wastegates and in turn wg controller or solenoids call for a pressure only source for operation to the side port and the bottom of the diaphragm for a TURBO application. Can you get away with a boost/vac source on a turbo car, sure and when using a single side port reference, you likely wont see any ill effect. Other than putting vac into the bottom of the gate when off boost.

It protects the turbo. If you develop a leak in the coldside and the gate is relying on boost from manifold to open to slow the turbo down you can easily run it up way past where it should be operating as the turbo could be throwing out 30-40psi to try and get say 15psi at the manifold to open the gate due to the leak. You would be unaware of the leak as you would still think your turbo is making your desired 15psi. When pressure is from the compressor cover itself it helps protect from a worse case scenario like this as you will see the pressure loss right away as the leak would immediately cause an observed loss of boost on your gauge run off the manifold. You would hear you turbo spool up and your gate open but not see the correct amount of boost at the manifold.

In short running the wastegate off the manifold can hide a boost leak and cause you to over spin/work the turbo and put more heat in the air and you wouldn't even know. Turbo's don't need to increase speed with rpm so controlling the turbo via gate is most optimally done with a pressure source pre intercooler where pressure and temp is highest. This effect is called boost sag on a turbo car, you get peak boost at say 3500rpms and then by 7k rpms your making 3-4psi less on your boost curve even though power and flow is the same. The turbo maintains speed and due to intercooler losses and the engine being less of a restriction at higher rpm boost "sags" in the upper rpms. Running the gate off the manifold would cause the turbo to keep accelerating with rpm to raise pressure and push more air.

This would not apply to a centri car running a gate on the coldside as blower rpm is already predetermined based on rpm and pulley size. You would want gate reference off the manifold for that setup as you are purposely making a controlled boost leak and you know boost at the manifold is less than at the compressor outlet up to the gate.

 

[05stroker]

Yes Billy, all wastegates and in turn wg controller or solenoids call for a pressure only source for operation to the side port and the bottom of the diaphragm for a TURBO application. Can you get away with a boost/vac source on a turbo car, sure and when using a single side port reference, you likely wont see any ill effect. Other than putting vac into the bottom of the gate when off boost.

It protects the turbo. If you develop a leak in the coldside and the gate is relying on boost from manifold to open to slow the turbo down you can easily run it up way past where it should be operating as the turbo could be throwing out 30-40psi to try and get say 15psi at the manifold to open the gate due to the leak. You would be unaware of the leak as you would still think your turbo is making your desired 15psi. When pressure is from the compressor cover itself it helps protect from a worse case scenario like this as you will see the pressure loss right away as the leak would immediately cause an observed loss of boost on your gauge run off the manifold. You would hear you turbo spool up and your gate open but not see the correct amount of boost at the manifold.

In short running the wastegate off the manifold can hide a boost leak and cause you to over spin/work the turbo and put more heat in the air and you wouldn't even know. Turbo's don't need to increase speed with rpm so controlling the turbo via gate is most optimally done with a pressure source pre intercooler where pressure and temp is highest. This effect is called boost sag on a turbo car, you get peak boost at say 3500rpms and then by 7k rpms your making 3-4psi less on your boost curve even though power and flow is the same. The turbo maintains speed and due to intercooler losses and the engine being less of a restriction at higher rpm boost "sags" in the upper rpms. Running the gate off the manifold would cause the turbo to keep accelerating with rpm to raise pressure and push more air.

This would not apply to a centri car running a gate on the coldside as blower rpm is already predetermined based on rpm and pulley size. You would want gate reference off the manifold for that setup as you are purposely making a controlled boost leak and you know boost at the manifold is less than at the compressor outlet up to the gate.

Thanks for the detailed explanation I guess because I am working with the centri blower that is why it's different.

 

[TzReddy]

So instead of running that direct vacuum line from intake manifold for boost controller would I be better off running it from the BOV or WG?

 

[702GT]

So instead of running that direct vacuum line from intake manifold for boost controller would I be better off running it from the BOV or WG?

Not sure I follow your wording.

I'm assuming you're asking if you can T off the WG or BOV line, in which case the answer is absolutely not.

The WG and BOV should each have their own separate pure source of vac/boost. It's okay if they all run on a single header from the manifold, but the line from the header to the WG and BOV should be uninterrupted and share sample with no other component. (By "header" I mean a block that has multiple smaller ports for which you can samplevacuum/boost. So a 5/8" Header could easily support 3 or 4x 1/8" - 1/4" sample ports. 1/8" is generally the most common sample line size. To each their own.) You don't want to share sample lines with other devices as it could cause errors in their designed function.

The MBC itself is required to be "in-line" with the WG, in other words a cut should be made to the line that feeds the WG and the MBC inlet port connected to the manifold side of the line, and the MBC outlet be connected to the WG side of the line. This is also true for the solenoid if electronic.

The electronic controller itself should have an independent line on the manifold header for sampling the boost level at the manifold, if that's where you desire your sample from. It should not share a line with any other device, including the WG line.

 

[TzReddy]

My wording was incorrect as I meant run my BOV directly to that port by itself or run the vacuum line from the WG to that port vs using the boost controller there. Then just run the boost controller to the t fitting from the fuel rail or something.

 

[702GT]

My wording was incorrect as I meant run my BOV directly to that port by itself or run the vacuum line from the WG to that port vs using the boost controller there. Then just run the boost controller to the t fitting from the fuel rail or something.

Invest in a vacuum header block. They aren't expensive. I wouldn't feed off the fuel rail sensor's line, it could cause issues, definately don't want issues with fuel.

 

[TzReddy]

So if I bought a vacuum block could I use the port from the intake manifold as my source to the vacuum block? Then everything else just plugs into that?

 

[702GT]

So if I bought a vacuum block could I use the port from the intake manifold as my source to the vacuum block? Then everything else just plugs into that?

Yes you can.