ITB Manifold Vacuum

[pos944rs]

Hello,
I've been reading this forum for awhile now and this is my 1st post. I am currently building an intake setup for a 2.5l porsche 4cyl. There is not much science to what I am building, just what I read and see. The question is what is the best way to obtain manifold vacuum now that I am losing my plenium after the throttle plate? Would a 3 1/16" line from each throttle body to a stand alone chamber work as a vacuum resivor? I need Vac. for the brakes and the fuel regulator. Could I also incorporate an air bleed into that resivor to control idle? The engine has been modified and it makes a alot of power. It also runs really well. I just like making things and this intake is the current project. I just feel that I am stuck on this vacuum issue.

Tom

 

[patprimmer]

Just pick up the vacuum from one runner after the throttle plate. You don't need a reservoir.

If you want more stable vacuum signal, take a line from all 4 runners and join via "T"s or via a very small manifold.

Basically the vacuum manifold can be just a stack of "T" fittings.

The volume and CSA of these lines and vacuum manifold will reduce pulsing in the inlet manifold, depending on relative sizes.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Deltona]

Take a look at Jenveys site Tom for some ideas:

http://www.jenvey.com/

There's a nice little diagram of the kind of thing you may need, go to 'Accessories' then at the bottom go to:
'Air Bypass Valve fittings. See instructions '

Have fun...

 

[pos944rs]

I should have said a 3/16" vacuum line from each unit in my 1st post. But I am thinking that will be too much volume if it is connected to each runner. Since the brake booster has a check valve in it, it should have enough supply of vacuum under a deceleration high vacuum condition. The vacuum manifold I am thinking about using will be large enough to hold a couple of ports to route to the few places I need vacuum. I appreciate the responces I have recieved.