QSV Opening Pressure Adjustment

[6.5L]

So I was looking at my QSV and I have come up with a theory I think is sound now. No margaritas were harmed in the making of this concept. So I attached a picture of the actuating arm on the BD unit. Spring tension inside the housing keeps the valve closed. Boost over comes spring tension and pushes the arm open. There is a fair amount of thread to play with. I think if I simply loosen that nut, back the arm off a few turns to reduce spring tension, and then re-tighten the nut, it will lower the opening pressure of the valve. The valve operation won't be affected since the position of the connecting arm (see photo for shitty descriptions of what I am talking about ) doesn't change, spring tension will still hold it shut, and boost will still overcome it. Valve position and operation isn't being affected, just spring tension. And it will still only takes a certain number of psi from closed to open no matter what psi it starts to open at since the valve still only has so much travel allowed. What do you guys think? I am going to mark it where it is, change it some, and then take it out for a test drive and see where my non-alcoholic theory gets me. And yes, I know I have a slight exhaust leak in the picture. That is soot. I dont think it is a large leak since that is all that has accumulated since I installed the valve. Maybe from when it starts up when it is cold and there are some clearances. Could have also been from before I tightened everything down again. Who knows?

 

[6.5L]

I also found this. So the black screw at the end of the canister next to the boost line would also have to be adjusted to allow full travel if you loosened the arm any

 

[Project57idi]

The black bolt in the canister is what controls the preload. Not the threaded control end. But I do agree that adjusting them both properly will allow you to adjust when the valve starts to open. Why are you wanting to adjust this? Wanting lower boost? Good luck with your testing. Also, if you're wanting help with something like this, you can always contact bd. that's why we buy from a reputable manufacturer, so we can get support after the sale

After looking at it (even though its not a qsv in the picture) it looks like BOTH control preload and travel, as a pair. I really hope you figure something out, as now I'm very curious!!!

 

[6.5L]

The bottom picture is a QSV, just for like a powerstroke or duramax. Same canister and operation though. And my thinking was that even if you backed the pre-load off, you would still have to loosen the actuating rod for it to move since that is what is keeping the rod from moving. And I did e-mail BD as well.

 

[6.5L]

And the reason for lowering the opening pressure is I don't need to run it up to 15psi before it even starts to open. my goal if I can lower the opening pressure, is to lower it, swap back to the smaller housing for quicker spooling, and not have to worry about over-boosting. My whole goal here is still to limit boost to 20psi and below. I am really just trying to put off doing headstuds as long as humanly possible while still making my truck better.

 

[6.5L]

I am also aiming for a starting open pressure of 12-13psi. My thinking is that by the time I hit that psi, I will be far enough up in rpm that I won't have to worry about the valve opening and not boosting anymore since I will have enough flow to still create boost.

 

[schiker]

It looks like the black screw in back sets the valve close point or how far it closes. How far the spring can push to relax and pull close the valve flapper thing. I suspect the idea is so the flapper doesn't hammer on the ID to a stop so it doesn't deform and stick over time. The connecting arm yoke would control the preload on the spring and would affect at which point it will start to open. So I think you are on the right track.

It may slightly affect the range of psi it functions though but I think in a good way. Since you have compressed the spring less to start its going to open sooner. Not sure if boost totally compresses spring in which case max opening will be still max spring compression but if max flapper opening is somewhere significantly less than max spring compression then max opening pressure will be less. Boost will still come on and push but since preload is less its a softer spring and the same max boost will compress the spring farther (its softer) and the flapper will open farther.

Spring force is spring rate (k) x compression distance (x). F=Kx Thus F1 =Kx is less than F2=K(x+preload compression).

 

[schiker]

But if you adjust one you will likely have to adjust the other. Since the close point of the flapper is important relation to preload or stop depends on how you want to look at it.

You could take off the yoke connecting rod and see if the rod pulls in more and that would prove its the stop more than the preload. Or It could be the preload and stop and the connecting rod must be adjusted to have the flapper stop correctly and not bind or overshoot sealing point or not intended position when closed.

 

[schiker]

The picture looks like its in limbo the spring is not at rest against the stop and the flapper doesn't appear to be shut either like its been actuated slightly and stuck in time for a picture.

 

[6.5L]

I think I am going to try to adjust it this week sometime or next weekend. Depends. I am gonna try to give BD some time to email me back

 

[pacificdrumma]

So its kinda like a turbomaster for the QSV.. i like it

 

[schiker]

Kinda sorta but key difference spring fights against boost pressure. some drive pressure pushes on flapper but boost pushes on a sealed piston and does the real control. Then it doesn't waste drive pressure away it redirects it to larger turbine volute.

It's kinda sorta like a simple mechanical variable drive pressure turbo.

 

[6.5L]

I did try to adjust it the other day but the way the rod sits, to grip for turning it I have to remove the turbo haha so maybe sometime this coming week I will do just that. That black "pre-load" bolt I wasn't sure would seal against boost if backed out, but it will. The allen head part of it will back out, then there is a nut with a built in gasket that can tighten down against valve again to seal it. Just requires a wrench and an allen. Gonna try to get to it. But thermostat crossover gasket on passenger side is leaking slightly. Not severe at all but it needs replaced. and while I'm at it, a radiator flush is in order as well. Time and money

 

[tanman_2006]

I did try to adjust it the other day but the way the rod sits, to grip for turning it I have to remove the turbo haha so maybe sometime this coming week I will do just that. That black "pre-load" bolt I wasn't sure would seal against boost if backed out, but it will. The allen head part of it will back out, then there is a nut with a built in gasket that can tighten down against valve again to seal it. Just requires a wrench and an allen. Gonna try to get to it. But thermostat crossover gasket on passenger side is leaking slightly. Not severe at all but it needs replaced. and while I'm at it, a radiator flush is in order as well. Time and money

Still better than a new truck payment. I should be done paying on my dmax next summer. $600/month SUCKS BALLS!

 

[Slim Shady]

Still better than a new truck payment. I should be done paying on my dmax next summer. $600/month SUCKS BALLS!

Amen to that, got into that real early in life then learned my lesson. I can afford a lot of repairs for a car note. I also can put the title in the glove box and walk away from it if I want to without the repo man comming to my house. Repo man intersting profession.

 

[tanman_2006]

Ya, I could have 2-3 real good running 6.5s with what I've spent on the truck. My friends wonder why it is the roughest looking truck I own (they haven't seen Ol' Blue in the day light) and my answer is it has to get paid off before I can spend a dime on anything other the necessities and it's gotta earn it's payment.

Sent from my Milestone X2 using Tapatalk 2

 

[6.5L]

I'm gonna swap to the small housing this week and see how it reacts to the fueling upgrades. We will see. Hopefully by the end of next week I will have my snow stage III water meth kit. With the turbo off I can get to the BD valve to try to adjust it. Turbo gets in the way so much.