HKS SSQV doesn't dump properly?

[Trondelond]

Just want to air some thoughts around the HKS SSQV I'm using at the moment. As far as I know, it differs a little in design from the conventional dump valve, meaning that the higher the boost - the harder the dump valve piston will seal. So - you won't suffer problems that you might experience with a spring loaded dump valve. Boost leak and such.
However, when running boost pressures over 1 bar, it sounds like a lot of the air comes out through the air filter, as opposed to through the dump valve. I'm wondering if this is an inherent weakness from the design type?

I've tried attaching both the "standard" vacuum hose to it, and I'm now using the "quad vacuum" mod. The result seems slightly better now, but there's still the sound of air coming out of the air filter the second I get off the throttle at high boost.

I'm considering going for a Forge recirculating valve, as this should have a quicker response when dumping, but it won't open at lower boost levels. I percieve this as less of a problem than the valve not releasing pressurized air at high boost.

Comments, thoughts, etcetera?

 

[PobodY]

Has someone been fiddling with the fine adjustment knob on it? - For some reason people seem to think it adjusts the boost pressure or the sound of the valve, when all it's doing is pre-loading the diaphragm to prevent it leaking under high vacuum.
I'd guess if it's new that's not the case, but with second-hand ones you never know what the last person was doing with it.

Is it just not big enough for the volume of air you're moving?

 

[Trondelond]

I don't have an adjustment knob on mine, so I don't think that's the issue. And this occurs even on the OE turbo at 1bar, I would think the SSQV was able to handle that sort of boost.

 

[whytie]

I've had that dump valve on most of my cars, ran 1.4bar and it was fine.

Load of fakes out there if you got it second hand?

 

[danr]

mine chatters when coming off boost. which i can affect with the said screw on the back. but i know the newer ones dont have screw as hks got fed up with all the questions about it! (as apparently it did nothing anyway). so, im baffled either way.

 

[Trondelond]

I've had that dump valve on most of my cars, ran 1.4bar and it was fine.

Load of fakes out there if you got it second hand?

Nope, got it off Nengun.
It's not that it doesn't work, it's that split second when you get off the throttle, and you can hear that it doesn't open quickly enough. So a lot of the pressurized air escapes through the air filter. You don't get the chattering associated with running no dump valve, as I'm guessing the valve is completely open before the air pulses mange to bounce back again from the turbo. So it opens, just a fraction of a second slower than I think it should.

mine chatters when coming off boost. which i can affect with the said screw on the back. but i know the newer ones dont have screw as hks got fed up with all the questions about it! (as apparently it did nothing anyway). so, im baffled either way.

Mine does that as well if I ease off the throttle slightly. I'm thinking that the pressurized air bouncing back and forth in conjunction with the weak vacuum causes the piston to flutter a bit. At least that's what I tell myself!

 

[danr]

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Mine does that as well if I ease off the throttle slightly. I'm thinking that the pressurized air bouncing back and forth in conjunction with the weak vacuum causes the piston to flutter a bit. At least that's what I tell myself!

yup, the puller (spring) must have a threshold. so the loss of pressure opens it, then as pressure rebuilds snaps it shut. so either on or off, no smooth curve. will flutter more with more pressure, less with less.