super harger blow off valve question

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
grandpa_spec
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super harger blow off valve question

Post by grandpa_spec »

Not sure on were these two nipples are meant to be connected.two on supercharged vt 5 litre with intercooler any ideas ?

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Holden202T
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Re: super harger blow off valve question

Post by Holden202T »

if its anything like mine, which it looks like it is similar, the one on the side of the blue area is the one you want to connect the boost too, this will keep the BOV closed under boost but as soon as you get off the throttle and it draws vacuum it should open.

i don't know why there is one on the bottom though, might be to direct air onto the other side of the diaphragm ?
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Re: super harger blow off valve question

Post by bldnut »

that looks more like a waste gate modded, the top hose in the blue section goes to manifold vac/pressure as holden202 said, the 1 in the lower side is used to regulate boost pressure if you were over driving the charger at say 15psi but only wanted 7psi you would feed boost into the lower hose to bleed excess boost pressure off
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Holden202T
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Re: super harger blow off valve question

Post by Holden202T »

yeah that was the only thing i could think too, my wastegate has the same setup with fittings on both sides but my BOV is only on the blue part.
grandpa_spec
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Re: super harger blow off valve question

Post by grandpa_spec »

So the top one goes to the intercooler piping, and the bottom one stays as it is with no hose on it ?
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Re: super harger blow off valve question

Post by delcowizzid »

top one needs to goto inlet manifold.the other one you could feed to the cooler pipework to open the bov even faster if required
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bldnut
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Re: super harger blow off valve question

Post by bldnut »

top 1 needs to go to the manifold, the other 1 can be done as delco said but need to be careful if there is a pressure differential between the cooler pipe work and the manifold the valve will bleed boost pressure off, to see if the valve is bleeding pressure tape some ribbons to the outlet of the valve and run it up on a dyno if the ribbons flap around you know there is pressure escaping
grandpa_spec
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Re: super harger blow off valve question

Post by grandpa_spec »

Can't seem to get a difinative answer so can someone use paint.or something and show me where to put lines

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Holden202T
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Re: super harger blow off valve question

Post by Holden202T »

Put a vacuum hose from the BOV fitting thats on the blue cover, then run it to somewhere in the manifold, like the same spot the fuel pressure regulator connects to or similar, you'll probably need a T piece.

vacuum hose on the regulator connects to the manifold just behind the TB in the middle below the fuel rail. or you can get it at the back of the motor where the hose connects to the regulator.
grandpa_spec
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Re: super harger blow off valve question

Post by grandpa_spec »

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This right ?