Well got the Type S in today, and it sounds excellent, the first thing I did was to do the single spring mod, and teflon taped all the fittings. Adjusted the valve to evomoto's specs and went for a test drive, first experimenting with VTA... well it sounded good, until i got to idle i notice this valve whistling at idle vacuum and also very very very light throttle,....even if i tighten it soooo tight i get compressor surge. Im thinking this single spring mod isnt all its cracked up to be. i even threw a CEL from VTAing, but that isnt my concern, it runs fine now with it recirced and the single spring mod, but i still think it is whisting/leaking at idle vacuum and low pressure. Seems fine during boost, but i dont think it should leak at all during idle?? anyone else have any problems?? my oil seals in the turbo will eventually go if I dont get this leak fixed. Im thinking about putting the other spring back in as well, but yes I am recircing, and yes i have done the spring mod, and fooled with the adjustment screw, no matter how tight, i get slight idle leak with the single spring. What gives???

 

Greddy Type S can be used for VTA or recirculating, now try recirc.

 

why dont you read my whole post first ...i am recircing...it is leaking at idle, no matter how tight i adjust...i found this out by VTAing where i could really hear the leak, but i still faintly hear it with it recirced too... a leak at idle is bad..any one else??

 

With the single spring the valve starts to open around 16 hg/in, that is right around stock idle vacum, so yes the valve is slightly open at idle in this configuration. This mod was never intended for VTA configuration, if your going VTA you need to have a lot of spring tension, or at the very least some sort of filter on the valve outlet. Unless your going speed density, that will create some drivability/idle issues.

I discovered that the whistling at idle is actually from to much spring tension, try loosening it slightly from where you first had it until the idle whistle goes away. If the valve does not open far enough at idle it resonates (whistles). I have not found an acceptable metod to get rid of the slight mommentary whistle that occurs at lite throttle lifts, but you were warned about that.

 

HMMM, i ordered A greddy type S from RRE they told me i didnt need to do any mods for the BOV. It comes slightly modded from them. But the smaller spring is not removed. Should i be concerned. I will be running stock boost until the UTEC arrives next week. They told me i should have no problems.

 

Well, with that configuration the turbo pressure is routed to the underside of the actuator piston. So when the throttle plates close the added pressure under the piston helps to open the valve sooner. This gives a similiar affect to lowering the spring tension accept at lite throttle applications where there may not be enough boost pressure to help it open fast enough.
I have talked with a couple of individuals who use this configuration and it does help, but they still experienced some minor drivability issues.
With stock/standard configuration, the manifold pressure is routed to the top of the actuator piston only. So as you start to run higher and higher boost levels the actuator piston top will always see virtually the same boost as the valve. So you will always have basically the same pressure pushing down on the valve as you do trying to force it open, plus there is the added 12 lbs of spring tension from the single spring. This is why it is nearly impossible for the valve to suddenly start to open at WOT as you start to run higher boost levels.
I keep bringing this simple fact up over and over again but it just doesnt seem to register with some people. With the standard configuration there is just no way any of these valves (including stock) are going to start leaking at higher boost pressures (unless a seal or hose connection starts to fail).

Now with the configuration that RRE is using, you are runing the same pressure on both sides of the actuator piston at WOT (essentially canceling out the effect mentioned above). So the only thing keeping the valve closed now is the spring tension. From what I have measured, the standard type S with both springs will start to open around 22 PSI. So for stock/near stock boost levels this will work ok, but if your really cranking the boost up this configuration will cause a leaky BOV.

Dejon has a setup they sell with a 1G (but it would work with any BOV) for this same configuration, that basically eliminates this problem. It is essentially a special control valve that removes the pressure feed to the underside of the actuator piston under WOT and then opens up again when the throttle plate closes. I have never tried it but in theory it should work well. It just seems like a lot of added complexity and hassle when you can just run the single spring, but to each his own.
The other option, (smog I ment to mention this to you), if your only running higher boost with race gas (say at the dragstrip), at that time disconnect the fitting tapped into the adapter and cap it. When your done racing lower your boost and reconnect it.

 

what you need to do is put the other spring back in (back to stock), loosen the adjustment screw all the way out, and then screw in just until you feel the slightest resistance, at that point go one turn further on that, recirc it and you should be good to go. I think all the spring theory to practice is crap.

 

i am beginning to think the same thing, I cant really hear the leak at idle right now with it recirced, but i am assured it is because of doing VTA first to be able to hear the leak. No matter how tight or how loose the screw, there was always still a small vacuum leak at idle with the single spring. This doesnt seem very right, and i doubt the stock blowoff leak at idle either. I just dont want my seal to go on the turbo from a leak, so hopefully it is fully closed at WOT.

 

also, should a BOV be totally sealed shut at idle?? seems like Greddy would have said something about removing one of the springs, and this is the only type of car i have seen anyone doing this on. Still dont seem like something is right with this setup.

 

iam using 2 springs, almost all the way out. and it works for me
i think this mod with 1 spring is BS thats it, because at idle the BOV is open, it shouln't be open at idle thats why it whisle.

go 2 springs inside - and almost all the way out,
and tell me how you like it..

later

 

sweet, yeah i will try that. I have the one spring in now like everyone says to do, and it seems fine recirced, but its still that feeling of it venting at idle vacuum that is killing me. I think it should be totally shut at idle, and im sure the stock one isnt open at idle vacuum because that is one stiff **** to open, i tried last night with my hand. Yes this weekend i may put the other spring in and back the adjustment way out and see, sounds like a plan to me. I am concerned about the people with single spring and it venting at idle vacuum.

 

Silver Surfer are saying that if i use the greddy type S config. from RRE it will leak when i adjust the boost with the UTEC.

 

The scary thing to me is that some people new to this forum/EVO modifications, might actually read the last few posts and actually believe them.
First let me assure everyone that the BOV opening at idle is perfectly safe in re-circulation configuration (and common for most turbo cars). Running the valve in VTA configuration has absolutely no performance advantages and will only cause erroneous readings with the MAF sensor. Running VTA on a MAF engine system just for the sound seems silly to me. If you want all of the air rushing noises, use an open filter intake it will make all kinds of noise.
As for the two individuals that claim the type S works fine with both springs, even with the tension adjustment all the way out, many others and I have found that this is not the case. There is a slight possibility that there is something unique about there type s valves or there cars that makes this true, but more than likely their idea of running good is somewhat different from most everyone else. They cannot explain why using one spring is BS, only that they think it is .

I have explained the valves function and operation, and backed that up with actual test data (which has been verified by others). But the best evidence is the countless individuals who experienced problems with the stock type s, performed the modification and came back to report how well it worked for them.

The stock valve is really not that bad, it has a very slight leak that will not get any worse as you increase boost. I measured a 2-3 WHP loss because of this leak, which isn't much. I and many others also found that you can get slightly improved drivability compared to the stock valve. Beyond these minor improvements the stock valve will work just fine, even at higher boost levels.

All of the information you could possibly want regarding this modification is already in the BOV testing thread sticky near the top of this forum. I do not intend to waste another moment rehashing the same information over and over again. Good luck with whatever you decide to do, I’m out.

Regards,

Eric

 

By equalizing the pressure on both sides of the actuator piston, the only thing keeping the valve closed is the spring tension. According to my bench testing, this configuration will start to leak only if you try and go above 22PSI. If you crank the spring tensioner down further you could go even higher, I didn't do that test so I don't know how much pressure adjustment there is.
But since the stock turbo won't make much more than 20PSI in the higher RPM's I don't think this is a big problem, also it might help keep your boost from spiking to much in the lower RPM's so...

Make sense?

 

Got my Greddy Type S from RRE and it was perfect from the start...All I had to do was install it , they modify it themselves..

Mine has been working great ,had to tighten the spring a bit because I raised boost,still blows off at low throttle and no leaks from what I can hear.........

It should of been perfect from the start....