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Idea For Bov Switch.

StealthX

By StealthX,
in Engines & Forced Induction

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StealthX Veteran

StealthX

Posted
Posted

Hey guys just got an idea I want to share with ya'll...

I've got a GFB Hybrid BOV on my X-Trail and it has a plumb-back configuration.

The idea is to somehow make a switch/circuit to activate the BOV or not.

So when the switch is at 'off' the BOV acts like there's no Vacuum line attached to it, and the turbo flutters its head off, then when its 'on', the BOV acts normal.

The reason behind it is I love a good flutter *cue the hatred*, I don't care how wanky it is, but I want at the flick of a switch, to have either a nice plumb-back sneeze, or a nice flutter on lift off, nothing over the top!

What I need is some sort of valve that would 'tee' into the vacuum line for the BOV, and be able to switch between 'open' and 'closed' (i.e. vacuum line blocked and unblocked) with varying voltages (5V or 0V)

Does jaycar or similar sell such a thing?

It'd be a pretty simple circuit, just take a voltage source from the battery/alternator (something under the dash) then run a resistor, the switch and the valve in series, grounded by the chassis/similar...

I'm assuming I'd need some sort of resistor to bring the circuit voltage down from 12-14V, to 5V.

I'm pretty comfortable with KVL, KCL and Ohm's Laws, so I'd say I'd need about a 10ohm resistor

in series with the device/switch, so that the device receives 0-5V instead of 0-14 volts. This may change depending on the signal that the valve is rated at (might not need a resistor at all).

Please don't be all hatin', just looking for some way to apply some of the uni stuff I'm studying atm, cos I could use this as a project for this electrical engineering unit im doing.

Any ideas? comments?

Thanks!

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PM-R33 Grand Master

PM-R33

Posted
Posted (edited)

I think I have found a flaw in your idea. Now correct my if I am wrong, but if you installed something that disengaged the vacuum line to the BOV, wouldn't that in essence allow the bov to leak open under boost as there is no pressure on the other side holding it in place?

Edited by PM-R33
StealthX Veteran

StealthX

Posted
  • Author
Posted
I think I have found a flaw in your idea. Now correct my if I am wrong, but if you installed something that disengaged the vacuum line to the BOV, wouldn't that in essence allow the bov to leak open under boost as there is no pressure on the other side holding it in place?

Yeah this may happen, I've noticed atm (with the boost that im running -10psi) that the BOV spring is still tight enough to stay closed under full boost and even under lift off too.

Good call though I might need to check this out more!

StealthX Veteran

StealthX

Posted
  • Author
Posted
you want a detachable wastegate basically

Ohk really? What's the wastegate got to do with the BOV functioning?

Regardless of the switch position (and assuming the BOV stays shut under boost) the car will still make and hold the same amount of boost pressure...

It'll just sound differnt lifting off the throttle.

STATUS Grand Master

STATUS

Posted
Posted
I think I have found a flaw in your idea. Now correct my if I am wrong, but if you installed something that disengaged the vacuum line to the BOV, wouldn't that in essence allow the bov to leak open under boost as there is no pressure on the other side holding it in place?

exactly right.

sickr33 Rising Star

sickr33

Posted
Posted

you can do what you want but you will need two boost feeds to your BOV

let me explane

the BOV only opens when the the pressure in the piping its connected to is greater then the pressure on the other side of the spring witch is fed by a boost line witch is connected to the opposite side of the throttle body than witch the BOV sits (bov on turbo side and boost line conected to the engine side of throttle body)

hence when you back off the throttle body closers an in-balance in pressure occurs in the BOV causing it to open.

BUT

if you take the boost line from nipple on the same side of the throttle body as the BOV (turbo side) the pressure will remain equal and the BOV will not open. (assuming it has a strong spring STOCK MAY NOT BE STRONG ENOUGH)

so to do what you are wanting you will need a feed from each side of the throttle body and some way of switch between the two.

for this i suggest either an electronic valve that has 2 inputs and one out put that allows you to switch between the two.

OR

2 normal open/close air or liquid valves where you have one on each boost line before they connect into a T piece and connect into the BOV

SO IN SHORT IS IT POSSIBLE YES!

IS IT SIMPLE NO!

STATUS Grand Master

STATUS

Posted
Posted
Yeah I see where your coming from, but I know for sure my bov stays shut under boost. The spring is strong enough...

you might be ok with the a/m bovs providing the spring is strong enough. the R34 bovs are actually open 4mm at idle and decel to smooth reverb and r33 are similar so dont try it on stockers.

Samon Proficient

Samon

Posted
Posted (edited)

I've been considering something like this for a while now...

Go ghetto :)

Swing past bunnings and grab a 12v electronic irrigation solenoid... put it in the plumb-back line, and you're done. When the valve is shut, you'll get flutter as it's blocked, when open you'll get the sneeze.

Edited by Samon
StealthX Veteran

StealthX

Posted
  • Author
Posted (edited)

Yeah they do, but they are $450 bucks lol.

Plus, when adjusted, they don't cause flutter, they only change the sound of the escaping air from the BOV.

Cool, but a different concept to what im trying to achieve...

[edit] wow i just saw that they are $720! lol my bad

Edited by turbo x-trail
rob82 Mentor

rob82

Posted
Posted

We have had a similar issue getting a bov to vent on supercharged x5 BMW with valvetronic as they run virtually no vacuum at low throttle angle/load. We ran a vacuum canister that accumulated vacuum as you drove and then used a 3port mac valve to turn vacuum onto the bov when required.

You could do the same thing but instead of a vacuum canister you would need a boost canister(quite dangerous) anth then use a 3port to swithch between normal manifold vacuum to theboost canister when you want it to flutter.

StealthX Veteran

StealthX

Posted
  • Author
Posted

Thanks for your positive input guys! I think I'm gonna go with sickr33s idea and have a "y" piece in the vacuum line to switch between post throttle vac/boost signal, then pre throttle boost. This way I can be assured that the piston stays shut under boost.

Now I've gotta find such a device. I'll start looking at jaycar and see where that gets me...

Messiah Mentor

Messiah

Posted
Posted

again, checkout the solenoid for an EBC, i cant recall the exact logic of the one i have fitted, but it has 3 hoses attatched, so i'm thinking 1 pressure source in, and the ability to electronically switch between one of 2 outs either totally or in varying degrees.

Rig it up backwards and you have 2 pressure sources in, of which you can select one.

btw my ebc is an eboost, not suggesting you go to the lengths of getting a whole kit, but it might give you a guide as to what solenoid it uses.

StealthX Veteran

StealthX

Posted
  • Author
Posted

Ohk sweet, looks like and ebc solenoid is the way to go! I've never used an ebc before, how is the solenoid wired up?does it just have a ground, positive and a signal line?

An ebc flows enough air for a wastegate actuator so in theory it should flow enough air to act as a signal for the BOV. Just need to nut out the wiring, I think I saw the turbosnart website has an installation guide for their range of ebcs. That should help me out!

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