Tial Q BoV behaviour

[boon]

I\'m now running a Tial Q BoV off my TMIC.

I think it has the 11psi spring in it.

It\'s closed at idle and opens with just a little bit of boost which is all good, but if I have the car in neutral and give it a good rev the valve opens about half way.

I assume I\'m just increasing the vac as theres no load on so it doesn\'t make any boost... but do I need a stiffer spring in there? As it is I figure it\'s going to open under heavy engine breaking.

[Guest]

Whn my mse one did that I just tightened it and worked fine. Did all the springs come with it?

Cool it runs...how does it drive?

[boon]

And the BoVs only come with 1 spring. New springs cost heeeeaps so I\'m gonna try shimming this one first. Or see if any of my gate springs fit in it.

[Rosssub]

My HKS Seq goes off %100 with a rev in neutral?

[boon]

 Rosssub said:

My HKS Seq goes off %100 with a rev in neutral?

Sorry, to clarify... if I open the bonnet and rev it at the throttle body, watching the valve, I can see the valveopening while I\'m holding the revs, not when I close the throttle.

[lachlan]

it wont open under engine braking .

it opens when you rev it coz the turbo is trying to build boost

if it doesnt sit open at idle then it wont open under engine braking

[boon]

 lachlan said:

it wont open under engine braking .

it opens when you rev it coz the turbo is trying to build boost

if it doesnt sit open at idle then it wont open under engine braking

So I must be getting a solid 8psi or so of pressure differential across my throttle body then, with the throttle at like 30% opening?

I can\'t really decide if that makes sense or not. Does that mean that at partial boost the valve will open? I\'m confused.

[Rosssub]

 boon']

[quote name='lachlan said:

it wont open under engine braking .

it opens when you rev it coz the turbo is trying to build boost

if it doesnt sit open at idle then it wont open under engine braking

/quote]

So I must be getting a solid 8psi or so of pressure differential across my throttle body then, with the throttle at like 30% opening?

I can\'t really decide if that makes sense or not. Does that mean that at partial boost the valve will open? I\'m confused.

It\'ll be the "in neutral/no load thing" like you said wouldn\'t it? Holding the throttle open with no load/no boost the vac is enough to hold it open (like an NA). With no instant pressure change (load or deceleration) after throttle opening for the BOV to respond to.

Edit: Which could also mean that your BOV is opening slightly under initial throttle opening (vac+/-??), then closing when boost comes on. Have you got a straight Vac hose from mani to BOV? Maybe restricting it slightly might help (pill or filter, smaller hose)?

[boon]

 Rosssub']

[quote name='lachlan said:

it wont open under engine braking .

it opens when you rev it coz the turbo is trying to build boost

if it doesnt sit open at idle then it wont open under engine braking

/quote]

So I must be getting a solid 8psi or so of pressure differential across my throttle body then, with the throttle at like 30% opening?

I can\'t really decide if that makes sense or not. Does that mean that at partial boost the valve will open? I\'m confused.

It\'ll be the "in neutral/no load thing" like you said wouldn\'t it? Holding the throttle open with no load/no boost the vac is enough to hold it open (like an NA). With no instant pressure change (load or deceleration) after throttle opening for the BOV to respond to.

Edit: Which could also mean that your BOV is opening slightly under initial throttle opening (vac+/-??), then closing when boost comes on. Have you got a straight Vac hose from mani to BOV? Maybe restricting it slightly might help (pill or filter, smaller hose)?

This is basically what I\'m concerned about - I\'m not worried about unmetered air because it\'s running a Link but it\'s the fact that the BoV doesn\'t exactly have a filter or anything that worries me just a little.

Yes, straight feed, using the factory hose. I don\'t want to restrict it as this will cause it to open slower and with the way it\'s built I\'m quietly hoping it will build boost quite quickly.

[Rosssub]

Then yeah, surely stiffer spring or shimming like you were going to. It might not go Psshhh as much but at least you know it\'s sealing when it should.

Edit: Longer BOV adjusting bolt?

[boon]

Tial\'s only have springs, no fine adjustment

But yeah, will shim or swap spring.