Vacuum lines and What it does
03-21-2005, 07:11 PM
#1
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Vacuum lines and What it does
Did some research on FAQ and search, but still not enough understanding
Can someone help explain to me a typical vacuum circuit for a turbo system involving FMU, BOV, wastegate, boost controller (turbo xs), boost gage, MAP sensor?
Are all this connected together? If it is, what does it do and what is happenning?
Pardon the noob-style question.
Can someone help explain to me a typical vacuum circuit for a turbo system involving FMU, BOV, wastegate, boost controller (turbo xs), boost gage, MAP sensor?
Are all this connected together? If it is, what does it do and what is happenning?
Pardon the noob-style question.
03-21-2005, 07:59 PM
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Re: Vacuum lines and What it does (elpiar)
A lot of the systems on the car are operated off of vacuum.
a BOV needs vacuum to open, when you let off the gas your car goes from boost to vacuum, the BOV uses the vacuum effect to open a valve to release excess boost.
A WG is actually controlled by boost. The WG actuator is connected to your boost source either directly to the compressor or somwhere down the intake path from the compressor. When the WG actuator starts to recieve boost pressure it will start to open.
A boost controller limits the amount of boost the WG gets. Without a BC, a WG would start to open as soon as the pressure starts to build, and stopping once the limit of the WG spring is reached. If you install a BC between the boost source and the WG actuator, the BC limits the amount of boost the WG actuator gets. Most manual boost controllers just limit the amount of boost pressure going to the actuator, usually by way of an adjustable valve or adjustable orifice.
a MAP sensor or Manifold Absolute Pressure sensor measures the absolute pressure in the manifold (duh). Just like how there are increasing levels of pressure, there are also increasing levels of vacuum.
Boost gauge is simple, it connects to the vacuum system and measures vacuum, and if you car has a turbo, it also measures boost pressure.
Modified by BlueShadow at 9:13 PM 3/21/2005
a BOV needs vacuum to open, when you let off the gas your car goes from boost to vacuum, the BOV uses the vacuum effect to open a valve to release excess boost.
A WG is actually controlled by boost. The WG actuator is connected to your boost source either directly to the compressor or somwhere down the intake path from the compressor. When the WG actuator starts to recieve boost pressure it will start to open.
A boost controller limits the amount of boost the WG gets. Without a BC, a WG would start to open as soon as the pressure starts to build, and stopping once the limit of the WG spring is reached. If you install a BC between the boost source and the WG actuator, the BC limits the amount of boost the WG actuator gets. Most manual boost controllers just limit the amount of boost pressure going to the actuator, usually by way of an adjustable valve or adjustable orifice.
a MAP sensor or Manifold Absolute Pressure sensor measures the absolute pressure in the manifold (duh). Just like how there are increasing levels of pressure, there are also increasing levels of vacuum.
Boost gauge is simple, it connects to the vacuum system and measures vacuum, and if you car has a turbo, it also measures boost pressure.
Modified by BlueShadow at 9:13 PM 3/21/2005
03-21-2005, 08:07 PM
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Re: Vacuum lines and What it does (BlueShadow)
and they all need to be connected to a boost/vac source. you can tap them off eachother, tap them from different places, or buy a distribution block to run them off.
03-21-2005, 09:02 PM
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Re: Vacuum lines and What it does (BlueShadow)
Thanks for your writeup, it's really helpful. I'm getting there.
Where does this boost/vacuum signal originate from? The throttle?
My wastegate has two port, vacuum and boost, which one I connect to what?
Where does this boost/vacuum signal originate from? The throttle?
My wastegate has two port, vacuum and boost, which one I connect to what?
03-21-2005, 09:09 PM
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Re: Vacuum lines and What it does (elpiar)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elpiar »</TD></TR><TR><TD CLASS="quote">Thanks for your writeup, it's really helpful. I'm getting there.
Where does this boost/vacuum signal originate from? The throttle?
My wastegate has two port, vacuum and boost, which one I connect to what?</TD></TR></TABLE>
There are several vacuum sources. basically any vacuum line going into the intake manifold after the buterfly is a vacuum source. But the best one is the big on that the brake booster goes to or maybe the FPR vacuum nipple.
Both of those ports on your WG are for boost sources. One can be used by a boost controller. Those ports are there so you can tap a boost pressure source to them. I'm pretty sure applying vacuum to those ports wont do anything.
Where does this boost/vacuum signal originate from? The throttle?
My wastegate has two port, vacuum and boost, which one I connect to what?</TD></TR></TABLE>
There are several vacuum sources. basically any vacuum line going into the intake manifold after the buterfly is a vacuum source. But the best one is the big on that the brake booster goes to or maybe the FPR vacuum nipple.
Both of those ports on your WG are for boost sources. One can be used by a boost controller. Those ports are there so you can tap a boost pressure source to them. I'm pretty sure applying vacuum to those ports wont do anything.
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