What are my available vacuum sources? (BOV related) - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

AdamP · 03-09-2007, 03:43 AM

I has a '91 Sil80 running stock 7psi of boost (SR20DET).

I'm thinking I have a weak vacuum. I'm looking at the BOV and even when it's making some lower boost (2-3psi not fully spooled) the blow of valve is not opening at all remotely. I only seems to open up at medium boosts (where is kind of bounces around) and at high (it opens up cleanly).

The BOV is an Blitz SS (but I had an ARC that behaved the same way) so I'm confident it's the line itself. The BOV is spotless and it is lubricated well. I donesn't even matter even if I pull the screw out and loosen it fully. It will not even budge at minor boost. The ARC had a softer spring and it didn't either.

Which lines can I use? Which ones are redundant. Right now I am running am running the FPR and the BOV off the same line with a t-connector. Also, what size should I get for the hoses? The Blitz itself has a larger vaccuum nipple than the ARC.

nrg · 03-09-2007, 03:51 AM

anything below 3psi isn't a problem with a bov. Don't run the bov vac source off the FPR vac source. On your throttle body, there's 3 vac source, two top, one large one bottom. You should have the bottom one pluged up, One of the top two goes to FPR. And the other one goes to the bov. This is how i have mine setup. The size of the hose doesn't mater. If you have a boost gauge, it gets T off the FPR vac. Your internal gate is probably getting its source from the cold pipe; if not, then T it from the same line going to the bov or the bottom nipple off the throttle body.

nsn240 · 03-09-2007, 11:12 AM

I have mine Similiar to his ^
Top Left TB --> FPR (T boost gauge)
Top Right TB --> BOV

OR

Top Right TB --> WG with T'd line for BOV (WG off turbo outlet/hotpipe)
I cant tell you how many times ive typed that. Plug the bottom TB nipple btw

AdamP · 03-09-2007, 11:46 PM

What parts are normally on the vacuum lines when the SR20 is stock?

I want to know that what I'm detaching will not be detrimental to the motor. Right now I have the right one running the FPR + BOV.
The left one is being used as well. The line goes around the front, over the radiator and connects to some accessory behind the right headlight.
The big one is hooked up to something as well.

g6civcx · 03-10-2007, 04:59 AM

The big one goes straight to the BOV/CBV. Don't tee this line off to anywhere else.

The small line on the top side goes to the FPR.

The small line on the bottom side goes to the EVAP canister near the radiator/headlight area.

03-09-2007, 03:43 AM	#1
AdamP Leaky Injector Join Date: Jan 2007 Location: Edmonton, AB Age: 39 Posts: 50 Trader Rating: (0) Feedback Score: 0 reviews	What are my available vacuum sources? (BOV related... only opening mid/high boost) I has a '91 Sil80 running stock 7psi of boost (SR20DET). I'm thinking I have a weak vacuum. I'm looking at the BOV and even when it's making some lower boost (2-3psi not fully spooled) the blow of valve is not opening at all remotely. I only seems to open up at medium boosts (where is kind of bounces around) and at high (it opens up cleanly). The BOV is an Blitz SS (but I had an ARC that behaved the same way) so I'm confident it's the line itself. The BOV is spotless and it is lubricated well. I donesn't even matter even if I pull the screw out and loosen it fully. It will not even budge at minor boost. The ARC had a softer spring and it didn't either. Which lines can I use? Which ones are redundant. Right now I am running am running the FPR and the BOV off the same line with a t-connector. Also, what size should I get for the hoses? The Blitz itself has a larger vaccuum nipple than the ARC.

03-09-2007, 03:51 AM	#2
nrg Zilvia FREAK! Join Date: Mar 2004 Location: CA Age: 40 Posts: 1,571 Trader Rating: (1) Feedback Score: 1 reviews	anything below 3psi isn't a problem with a bov. Don't run the bov vac source off the FPR vac source. On your throttle body, there's 3 vac source, two top, one large one bottom. You should have the bottom one pluged up, One of the top two goes to FPR. And the other one goes to the bov. This is how i have mine setup. The size of the hose doesn't mater. If you have a boost gauge, it gets T off the FPR vac. Your internal gate is probably getting its source from the cold pipe; if not, then T it from the same line going to the bov or the bottom nipple off the throttle body. __________________ driftingisgay.com

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03-09-2007, 11:12 AM	#3
nsn240 Zilvia Addict Join Date: Aug 2005 Location: pa Posts: 642 Trader Rating: (1) Feedback Score: 1 reviews	I have mine Similiar to his ^ Top Left TB --> FPR (T boost gauge) Top Right TB --> BOV OR Top Right TB --> WG with T'd line for BOV (WG off turbo outlet/hotpipe) I cant tell you how many times ive typed that. Plug the bottom TB nipple btw

03-09-2007, 11:46 PM	#4
AdamP Leaky Injector Join Date: Jan 2007 Location: Edmonton, AB Age: 39 Posts: 50 Trader Rating: (0) Feedback Score: 0 reviews	What parts are normally on the vacuum lines when the SR20 is stock? I want to know that what I'm detaching will not be detrimental to the motor. Right now I have the right one running the FPR + BOV. The left one is being used as well. The line goes around the front, over the radiator and connects to some accessory behind the right headlight. The big one is hooked up to something as well.

03-10-2007, 04:59 AM	#5
g6civcx Post Whore! Join Date: Apr 2004 Location: Virginia, USA Posts: 5,764 Trader Rating: (5) Feedback Score: 5 reviews	The big one goes straight to the BOV/CBV. Don't tee this line off to anywhere else. The small line on the top side goes to the FPR. The small line on the bottom side goes to the EVAP canister near the radiator/headlight area.