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Discussion Starter #1
As title.

Can you do that with a weak enough spring (5psi maybe) without the diaphram inside ripping?

:confused:
 

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yes, this is how we controlled boost when we first started playin with turbos back around 99-2000
 

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Discussion Starter #4
Great stuff. Good news gets me part the way there then.

The backpressure thing is an issue, as although you have the boost pushing on the top port to hold it shut, I guess the backpressure can never be lots higher than the boost, certainly no higher than the highest spring rate your vac can pull open?
 

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Discussion Starter #6
Ok, I've been experermenting with this and already ran in to a problem.I have been using some cheap no-name wastegates just to try things out, and while its fine with higher spring rates, with a 6psi spring (that seems to be cracking pressure, properly 'open' is far higher) the thing doesnt go fully back in to its seat once the vac is off.Not exactly sure what its rubbing against to stop this, a quick push with my finger and its back in place, but it does.Can someone confirm that with a quality wastegate this will not be an issue? And what brand? Tial?
 

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Larger JGS have no diaphragm so you could run vacuum with no worries.
Yes the W/G should return to its seat.

You could run regulated pressure to the bottom of the gate to have the gate open quicker.
 

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Larger JGS have no diaphragm so you could run vacuum with no worries.
Yes the W/G should return to its seat.

You could run regulated pressure to the bottom of the gate to have the gate open quicker.

I guess I misunderstood . I thought we were talking about the exhaust side of the gate getting vac from the downpipe . Is this possible with how I have mine plumbed ? Would there be vac on the dump pipe ?
 

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Maybe not.
 

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Most times it is back pressure, pre-turbo, open the w/g. Especially with many people being so fearful of a larger hotsides.
I have never check for negative pressure in the out of a wastegate.
 

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I can't exactly see what's going on with your wastegate setup but if u have it plumbed into the downpipe then yes the backside of the valve would probably see vacuum from the air stream in the downpipe, is it opening your wastegate? I would doubt there is enough there to open it alon but the psi dif on either side adds up
 
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