I noticed as the car is idling; there is a small amount of air escaping where the valve meets the seat. Obviously; it's partially open. Also, when the electric cooling fan comes on and the idle drops for a moment; the BOV opens and closes. It seems to operate fine when driving.
This BOV has the spring tension adjustment on top. How should I have this adjusted?
Thanks!

 

Should be just closed or cracked at idle.

 

It sounds like I have it adjusted correctly. Thanks.

 

1. you need a pressure test to ensure the bypass does not leak during boost. Any leaking air in turbo applications causes excessive wheel speed, high IAT, high EGT, High EGP and results with poor performance and possibly engine damage.

2. The ideal route for bypass at idle and near idle conditions is recirculated to the pre-compressor intake. Look at any factory turbo engine for the details. The practice is, turbos impart kinetic energy to air molecules which leave the housing with a velocity component. Those air molecules should be allowed to recirculate back to the pre-compressor intake to conserve their kinetic energy. This allows the compressor wheel to speed up, achieve higher rates of impeller RPM than would otherwise be possible for those conditions, resulting in fewer turbo lagging, improved response off idle. If the bypass closes for any reason at low speeds the air molecules lose their kinetic energy and turn to a pressure scalar which forces them backwards through the compressor causing surge condition and this slows the compressor wheel down causing excess turbo lag and reduced impeller wheel speed. It can be seen easily using a compressor wheel speed monitor.

 

Which part of your reply answers my question of HOW to adjust the BOV?

 

The whole thing is the answer. Where do you need help interpreting? Bolt some parts you don't understand.

Quick summary:
1. Bypass should be open at idle and during 'power braking' while you hold the throttle open and the brakes at the same time, car is not moving but you are applying half or full throttle. This spools the turbo while you stand still. It won't work if the bypass is closed, however. Compressor will surge condition and air will flow backwards through the blades killing wheel speed.

2. Bypass should recirculate like an OEM turbo car back to the pre-compressor inlet to conserve kinetic energy imparted to air molecules leaving the compressor housing. If un-recirculated, kinetic energy is lost and this will cause lower pressure at the pre-compressor wheel stage which will negatively affect turbo spool character.

These can be seen easily using a compressor wheel speed monitor.

 

Like this
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I recently set this car up properly with the bypass recirculation, open at idle and part throttle before boost properly

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Air molecules leaving compressor contain a velocity component vector, kinetic energy with a direction. You recirculate these back to the intake so their velocity is conserved somewhat, allowing increased pressure before the turbo intake, which leads to improvement in spool character, flow rate of the turbo. Its a secret, most people don't know how important this is. Bypass goes as close to the compressor as possible conserve maximum energy and fastest pressure drop between the housing and the bypass.

 

They come integrated to some styles of modern compressor housing now, example of integrated unit:

https://www.turbomaster.info/eng/turbos/recirculation.php

The description is poor, but meh close enough.
It allows the turbo to operate to the right side of the surge line and maintain wheel speed.
Releasing the air instead has a similar effect but the lost kinetic energy kills wheel speed a little. Still better than surge though. I recommend a wheel speed sensor so you can see for yourself.