North American Turbocoupe Organization



What happened ti my turbo, lowered boost levels
Pete D Offline
Administrator
#11
Not vacuum, vacuum has no affect on the WGA
Pete Dunham


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amar67 Offline
Junior Member
#12
Pete D Wrote:Not vacuum, vacuum has no affect on the WGA

Pete, sorry for this question if it's a dumb one. I'm still trying to learn how all this vacuum and PSI works when it comes to the WGA and the WG. I think I do understand how the WG works and how it impacts the boost. I also understand that the WGA moves the rod to move the WG. But what has me a little confused is, you said above that Vacuum has no affect on the WGA. But we use vacuum through the Gillis valve to the WGA. I know the Gillis doesn't convert vacuum to air pressure so how does it actually work with vacuum when we are driving the car?

As you can see, I'm still learning... is there a good thread or article I can read to help me better understand how vacuum is used for the WGA?
1987 Thunderbird Turbo Coupe - 5 Speed Manual


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Pete D Offline
Administrator
#13
The gillis is designed to be closed under vacuum, and doesn't respond to positive air pressure until that pressure gets to the to the desired positive pressure that the valve is set for. The valve just ignores vacuum and it is closed so it does not "pass vacuum" to the WGA (in theory).

The WGA only responds to positive pressure. It ignores everything up to the minimum boost level that it is designed to respond to - about 9.5 psi for a stock ford WGA

Some devices respond to vacuum (speed control, flow control doors in the manual heat/ac system) Some are designed to respond to boost only. Some vacuum operated devices would be destroyed if they "saw" boost, for example the speed control system. That is why there are one way valves in that circuit, so boost can't get to the device. Some things respond to both, like a combination after market vacuum/boost gauge.

Here is an article that may help: http://turbotbird.com/faqs/#How%20Boost%...ols%20Work
Pete Dunham


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Pete D Offline
Administrator
#14
The WGA does not respond to vacuum, only positive pressure. The WGA/WG are there to limit boost. The engine is never in vacuum when it is in boost.
Pete Dunham


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Ramos617 Offline
Member
#15
Ok well up until today i was still getting only about 8 psi of boost

Since i had the day off I made it a priority to fix this problem
I got the intercooler to take a look at things and everything looked ok, the WGA was still good too

After reading the last couple posts trying to understand how the WGA works i finally figured out that my boost valve was installed backwards
I have no idea how that happened but somehow I must of installed the lines wrong, It just baffles me how this must of happened before that day on the onramp but my boost levels stayed consistent at 16psi. On top of that my boost levels stayed consistent at around 8-10 psi up until today with the lines mixed up

Any ways after figuring that out, I reinstalled it correctly, took her for a drive and theres the boost Ive been missing.
Thank you guys for the help.
1987 T-Bird
Too much stuff to list
Running better than ever
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