Cosworth Plenum - Why Check Valve?
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The Cosworth Plenum Installation Instructions, in step #18, mention installing a check valve in the brake booster vacuum hose. See image and picture from the instructions below.
![](http://i15.photobucket.com/albums/a361/___jb/My%20G35/Cosworth%20Plenum/CosworthPlenumInstructions2.jpg)
![](http://i15.photobucket.com/albums/a361/___jb/My%20G35/Cosworth%20Plenum/CosworthPlenumInstructions1.jpg)
What makes the Cosworth Plenum require this check valve? Why does the Cosworth Plenum require this check valve and not the OEM plenum? Anyone know what this check valve does?
Could it be something to stop boost from going into the brake booster? So, maybe it's not needed on an NA car?
I don't mind putting the check valve on. It's certainly not difficult... I just like to know why I'm putting something on and what it does. Have other people installed this check valve when they installed their Cosworth Plenums?
![](http://i15.photobucket.com/albums/a361/___jb/My%20G35/Cosworth%20Plenum/CosworthPlenumInstructions2.jpg)
![](http://i15.photobucket.com/albums/a361/___jb/My%20G35/Cosworth%20Plenum/CosworthPlenumInstructions1.jpg)
What makes the Cosworth Plenum require this check valve? Why does the Cosworth Plenum require this check valve and not the OEM plenum? Anyone know what this check valve does?
Could it be something to stop boost from going into the brake booster? So, maybe it's not needed on an NA car?
I don't mind putting the check valve on. It's certainly not difficult... I just like to know why I'm putting something on and what it does. Have other people installed this check valve when they installed their Cosworth Plenums?
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it might be due to the fact that the cossie intake uses a split plenum vs a common, which could cause wave pulse variances that disrupt the vacuum signal--this would only be true if that vacuum hose goes to one side of the plenum.
other than that idunno.
other than that idunno.
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![](http://i15.photobucket.com/albums/a361/___jb/BrakeBoosterVacuumHoses.jpg)
The Cosworth plenum has carbon fiber side plates. It's probably impossible to place a fitting in the same location as on the OEM plenum. Cosworth supplies a 90 degree fitting that mounts near the throttle body. They also supply a new length of hose that does not have a check valve in it. Thus the need for the additional check valve.
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I haven't installed the plenum, so I can't answer your question. I need to get a few things taken care of first.
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