G-ELL wrote:
Think about it Adam, there wouldn't be vac at the y-pipe. The reason motors create vac is because the pistons suck the air in and the throttle body makes a restriction. There's no vac at the y-pipe because it's before the throttle body.
On an NA plenum, there's only 1 small nipple to source. It's in the same spot where the BOV is sourced at in a turbo plenum. The only other vac/boost source is the P port on the TB.
John, your either your car isn't making boost, there's an issue with your gauge, or you're just not seeing it (it's in a bad spot to see while driving). When I looked over your vac routing, it was all correct.
yes greg, I understand the no vacuum on the back of the y-pipe. I was asking just to make sure all the numbers make sense.
What I'm curious about now is the NA plenum itself, and the little motor to flip from short to long intake tubes, and where the vacuum/boost is pulled/rounted in there. I'm curious if that is messing with the ports we are trying to take readings from.
Which is also why I wanted to know the max boost he saw and when, compared to what he saw in ANY of the plenum ports. If he's just getting a jump in pressure when he shifts its the boost backing up on the butterfly valve. if he is honestly seeing boost in the y-pipe but not in the plenum, something is wrong with that.
There are NO ports on the back of an NA plenum? none for the clutch assist, or brake assist that he could also tap? well color me green.
You should not have pressure on one side of the butterfly valve, then boom, it's gone. that just seems odd.
