SILVER SURFER

The 1G valve looks like it might work well in an EVO, (from what I can see in the pics) it does seem to have a good valve to actuator diaphram ratio, and a rubber seal on the valve. You could always make a tube/flang for the inlet side like I had to do with the Greddy valve, but the outlet tube needs to be 34mm also, what size does the 1G have?
As I said most of the after market valves use relatively heavy springs, that is why there was some surge on several of the after market valves in the SCC test. Most factory BOV's use very light spring tension, I think because that's probably all you really need in most cases.
People keep saying these valves leak at higher boost levels, but I cannot really understand how or why? If you have 30 PSI on the valve and 30PSI on the actuator piston (that has a larger diaphram area) there is no way the valve should leak.
I believe where the spring loading comes into play is really only during the transition points (I may be stating the obvious here but..). As the turbo is spooling up it is possible that the valve will see a higher presure than the actuator, with a very light spring tension I could imagine the valve might leak during this time, increasing turbo lag. So you want to find the highest spring tension you can use, but not so high that it causes surging, that's your happy place.
Getting a BOV with the largest valve to actuator diaphram ratio and then finding the optimum spring tension will be the best situation regarding the BOV.
I have no idea what spring tension the 1g valve uses, but I cannot imagine that compressing the spring 1 or 2 mm by crushing it, can give you a significant increase in tension. With the aftermarket valves (besides being shinny and all), by changing springs and the adjustment screw, you have an almost infinite adjustability. The whistling that I mention happens because with the optimum spring tension under light throttle lifts the vavle does not fully open and hits a resonance (like a whistle). If you put a much lighter spring in, it would open a great deal more, changing the sound to an air rushing woosh, like you described happening with the 1G.
I also rubbed of that purple finish off on the actuator cap, it is kind of obnoxious.
I was interested in that three way pilot valve they were using for the helper valve. That could be used on the Greddy valve also, allowing the use of an even heavier spring. Better response without surging, I may have to call them, I could not get the test data page to come up.

Thanks for the info,

Eric

eslai

Crushing the valve works very simply--the spring now has more preload on it. You get the same effect out of the Greddy Type-S by turning the adjustment screw.

Actually, you're the first person I know of that's ever taken springs out of the Greddy Type-S. I'm glad it's working for you, but it sounds rather goofy.

You should have tried using the assist barb--it really does work. And if you have equal pressures on each side of the valve, why don't you believe that it would seal with spring pressure alone? You have equal forces acting on the valve from both sides. You just said this in the post above, but in your original post in this thread, you stated your belief (which I don't agree with) that, "with that configuration under acceleration/boost you would have the same pressure on both sides of the actuator piston, then the only thing keeping the valve closed would be the spring tension. Even with both springs installed it is not strong enough to keep the valve sealed at 19 PSI."

[kerpal]YOU TRY TO CONFUSE!!!![/kerpal]

EvoInSoCal

iTrader: (1)

yeah, i am still confused about taking the spring out to make the type s work better, it makes no sense to me either. From my experience with it, the type s is not stiff enough, for the most part, or if youtighten it down too much, then obviously it's too tight, there doesn't seem to be a happy median for that bov. I have not tried hooking up that bottom nipple on it though, and it seems tha quite a few people have had success by doing that, and still, some haven't. Crushing a 1g valve has been a trick used for many years, and it works, and works well if done correctly. Crushing a 1g valve maes more sense than taking the spring out of te type s to me. Also, i talked to a few shops, and they actually prefer the evo valve over the 1g. Just a bit of info or all of you. Basically, IMO stay away from greddy on this one, and go with something like HKS with recirculating kit, etc.... or stay stock, nothing wrong with that. Thats an extra $200-300 you could spend on a boost controller or something ...............

Zeus

iTrader: (66)

...a few individuals have posted that the EVO's OE valve is leaking and dynos of increased whp with just a BOV swap... think a shop or two has done the same... on the other hand, some people/shops are not seeing a benifit. Seems it is starting to look like the cheap plastic valve is a hit or miss affair. I'm changing mine for peice of mind... not to metion longevity.

SILVER SURFER

"Crushing the valve works very simply--the spring now has more preload on it. You get the same effect out of the Greddy Type-S by turning the adjustment screw."

Um yeah,, that's kind of obvious, but with a spring travel of 20-30mm, compressing it another 2 mm will increase spring tension how much? I would guess not a lot.


Actually, you're the first person I know of that's ever taken springs out of the Greddy Type-S. I'm glad it's working for you, but it sounds rather goofy.

You must not get around much, but when you say "it sounds goofy" Why? I suppose if you just blindly buy and install (probably have someone else install) parts that some tuner tells you to do, then you might think that way. I personally question everything, no matter who's saying it, especially when it comes from the internet. Use info like what I put out here as another perspective, apply your own logic to it, do your own testing and come up with your own conclusions, and feel free to share.

Compressing the spring even with the larger variations allowed with the adjustment screw still gives you a limited range of spring tension adjustment. To go beyond that you have to start swapping springs. You know what's Goofy? trying to say that there is one valve, with one spring, that will work with all the different applications out there.

"And if you have equal pressures on each side of the valve, why don't you believe that it would seal with spring pressure alone?"

Because none of the valves I tested would stay closed at 19 PSI with out applying at least some presure to the actuator. (this info is in my original post)If you are only making around 10 PSI max then sure, a few of the aftermarket valves will stay closed.

Rather than going on like this, I will just say:

In two of the most recent responses , I have gotten people telling me that I am wrong, but with no real explination why? Other than thats just not the way it's been done in the past. To me this is just blowing smoke, and responses like that I can do without. If my posts confuse you then maybe you should just ignore them

eslai

I swear, everyone on the 'net has the most fragile of egos. Why does everyone have to react so poorly to questions?

The force applied by a spring is determined by the spring constant multiplied by the distance the spring is compressed or extended.

With that in mind, compressing the spring by 2 millimeters more than its original travel of 20 or 30 millimeters would increase the force being applied by the spring by up to 10%.

You don't think that's enough to make a difference, eh?


You must assume too much quite often.

I've been carefully modifying my second-gen Eclipse since 1999. Been crewing for prepared race cars since 2001. I organize track events at Buttonwillow Raceway and Willow Springs International Raceway for SoCal-DSM. Currently known for my ability to tune AEM EMS systems on street cars.

I know that's not a lot of credibility there, but hey, at least I've been watching for a while. Believe me, I am also not a fan of internet-lore.

Hmm. I don't recall saying that. All I remember saying is that you modified the Greddy Type-S in a way that I've never seen done before.

The adjustment screw still gives you a limited range, granted. You generally tighten the adjustment screw such that the BOV will hold the amount of boost you're trying to reach. The assist barb has always cured any part-throttle lifting issues that ever occurred on the DSMs I know about, all with various ranges of boost levels and modifications of course. I've just never heard of anyone taking out any springs.

Eh, I'm not sure I follow how you tested to see if you had equal pressure on both sides of the valve. To test this you'd put 19 psi on the bottom and approximately the same on the top. Well, how do you verify that anything is getting past the valve in that case? Enlighten me, seriously!


I'm going to cut you some slack and really really not bite on any of your insults in this post.

Have a nice day.

EvoInSoCal

iTrader: (1)

if you want to stop a BOV from leaking, wouldn't you want to put more pressure on the valve inside it? Thus, wouldn'e taking one spring out creat less tension, and actually allow the BOV to be softer? I understand the whole issure behind the valve's travel distance though, and how the screw on the type s only will give the inside valve less travel if yo go too low, but removing a spring won't help that issue from what i can gather. I really might be just missing the point here, but i just don't see how that works, not saying that it doesn't, but i just can't see from a tuner/technicl view how that works. Also, atually capping off that lower vaccum port on the BOV isn't recomended by greddy at all, and i would tend to think that doing so would be negative. I'm happy it works for you, but i'm still stumped on the technical aspect of it all.

It's like wanting more travel on a suspension setup, and you remove the helper spring from a coilover, or cut a few coils off the spring while at the same time wanting to get a tigher, more responsive reaction from the suspension, it just doesn't add up.

oh well, i'll sit back and keep trying to understand it, meanwhile, i'll just stay stock or just buy another proven BOV like HKS, or something, where NO MDIFICATION IS NEEDED TO WORK PROPERLY.........

SILVER SURFER

Yes, I got a little snippy with you and I am not proud of it, but when I take the time to share information and then someone starts calling me names (like "Goofy") well, you should expect to get some negative feedback. Although I am sure you meant it in the best possible way .

I think we have just about beat this topic to death, if I knew what I was getting into I would have probably just kept to myself. Anyway, regarding the last few questions.

I have not tested this valve so I have no idea, but considering that most aftermarket valves have springs that are 100% to 300% higher than some stock valves, 10% seems small by comparison.

I have to wonder how it was determined that the 1G stock valve was actually leaking? How badly was it leaking? What sort of performance gain was seen by crushing it? Did anyone test for leaking after using the assist barb?
As for changing spring rates, most of the aftermarket manufacturers offer there BOV's with a variety of spring rates. Changing spring rates on BOV's is actually a very common occurance in many forms of motor sport tunning. Most people get there standard (highest) spring rate because they have no idea what they really need.


Yes, I actually applied 19 PSI to both sides of the actuator, and yes a small amount of air escapes from the valve shaft but not enough to significantly reduce the pressure on the underside of it. The result was that the valve leaked quite a bit in this configuration, with 19 PSI on the valve.
While I have no doubt that the "assist barb" will improve drivability issues I suspect that in many cases it can also cause valve leakage. Unless you actually do testing (bench or Dyno) how do you know? Unless the leaking is severre, your talking about minor HP loss 3-5 HP, on a 200+ HP car you cannot feel that from the seat of your pants.


Yes, the stock EVO BOV has plenty of spring tension (in fact it's the highest I have ever seen on a stock BOV). The problem is the valve does not seal completely even when it's fully closed. I found with the Greddy valve, that I could use a lower spring tension which improved part throttle drivability and still get it to close completely, improving HP (dyno tested).
As I have already said, there are probably many other valves that would work just as well, but I can only comment on what I have. I figured this info would help those peolpe who already have the Greddy and it would give others some ideas on what to look for when selecting there BOV.


I think your right about this, I found that a small amount of air was getting past the valve shaft from the lower actuator chamber. So I initially thought I should cap it to prevent any unfiltered air from getting into the engine. After re-evaluting this idea I think the chance of any significant air contamination from this barb is extremely slim. It will also create a small pressure chamber on the under side of the actuator that will some what hinder the valve operation, so I have decided to remove the cap.

I could be wrong but the Pruven BOV look's just like the Greddy type-s, only with a custom actuator cap. I have also read that some people have noticed some drivability issues with that BOV, they probably have the same two springs that I started with.

Chris in HB

iTrader: (3)

I am fortunate to live literally around the corner from Rhys Millen Motorsports. After a long discussion with the techs, the conclusion was NO advantage to a BOV. They routinely race rally-prepped cars with 400+ hp and have yet to need a BOV. A good turbo upgrade and free-flowing air are the biggest contributors to performance. If you want to hear that "whoosh" noise, play Gran Turismo....

Zeus

iTrader: (66)

Don't give up posting good test information due to a critic... If everyone gave up passing on good ideas at the first sign of a naysayer, we'd all still be chasing our food...

eslai

Hey, all I said was that "it sounds kind of goofy"--I didn't say anything about you personally. Consider it me scratching my head and saying "I don't get it", not, "you don't get it."

It's enough to make the valve hold up to 20-22 psi rather than 18 psi, as everyone in the DSM world has known for a long time now. No one's trying to run 30 psi with these things.

Damn, there was some GREAT test data at Dejon Tool, but his link is dead (it's on the same page that sells the BOV), as you noticed. I'll email him about it and see if he can bring it back up--it was very good too. It had all the data you just requested.

Yes, the valve leaks a bit, even with crushing and all that.

I played around with it on a TurboXS H34. The H34 has two ways to adjust the load on the valve: you can add washers behind the spring to preload it (like crushing) or you can swap out the spring. When you receive the valve it comes with some washers to do that with, but no adjustment springs.

I went back and forth with Mark McGovern of TurboXS for a few weeks trying to get mine to work well. Went through four different springs with different windings and lengths before finding one that worked well for my application.

See, here's why I questioned you in the first place. You're saying that it leaked with 19 psi on both sides of the valve. But at the top of this page you said this:

"People keep saying these valves leak at higher boost levels, but I cannot really understand how or why? If you have 30 PSI on the valve and 30PSI on the actuator piston (that has a larger diaphram area) there is no way the valve should leak."

And I agree with you on that! If you have equal pressures on both sides of the valve, then it isn't leaking due to the valve not being seated--any leakage is due to the valve seal not being the best in the world. The spring load is plenty strong enough to withstand a minor pressure differential. It wouldn't make a difference if you applied 30 psi or 19 psi to both sides since the pressure differential would still be in the same range.

Do you care if it leaks, since you can't feel the minor HP loss? Would there be a minor HP loss at all on the car if it the compressor was having to work a wee bit harder to generate the set boost level or not? It's hard to say, y'know? No black and white in this world--only grey.

Personally I think the stock BOV is well-suited. When you guys start upping the boost more, then probably it'll have to go, eh? Not that y'all can up the boost much--19 psi is a pretty heady amount of air on pump gas already!

Zeus, I'm not here as a naysayer. All I said was that it seemed goofy that he did the spring thing, and then I said that he should have tried the assist barb, which apparently he has not (uh, I think...right?) With the assist barb in place, he probably wouldn't have needed to remove the spring. I don't have any test data that says that the assist barb DOESN'T cause leakage, all I offer is the fact that Road Race Engineering has been using them on all of their race cars for years now with the assist in place. They don't send any cars out of the shop without that assist barb in place. They generally shake their heads when they see people with chugging valves because that barb is capped off. People mod 1G BOVs so that they have an assist because the crushed valves sometimes can be a bit rough when popping off otherwise--but it depends on how much it was crushed and who's using it (and with what).

Why do I care? The results are the same if the spring is removed, right? Well for one--disassembling the Greddy Type-S can cause a number of problems. People have a hard time getting those things back together without ripping the diaphragm. Talk about boost leak!

If surgery is not required, then why elect to do it?

Just my $0.02. Flame suit on.

Zeus

iTrader: (66)

Relax and don't be so defensive, I made a general statement. Hell, I've got a 1st Gen valve in the mail...

eslai

I thought I was being pretty relaxed. Damn the internet!

Incognito

iTrader: (8)

Wow, you people are crazy, arguing over all of this.

I have access to a GReddy type S BOV, so I tried this mod on my Evo. Took the smaller (middle) spring out of the BOV and put it back on my car, running it recirculating, like stock. The thing does drive like stock, if not better. Part throttle, you don't get that bucking **** anymore. I'm guessing that at part throttle, it cracks open, and the readings between the mass air meter and the amount of air in the intake pipes is the same. Anyway, it works. However, I did find that I had to crank the center bolt close to 1/2 way down for it to seal. I booosted the **** out of the car, kinda (22psi), to check that the BOV holds, and it does.

So yeah, if U have the GReddy BOV, and U want the car to drive like stock, do this mod. Oh yeah, the BOV isn's as loud as if you were to leave the middle spring in (the GReddy isn;t loud to begin with, so with the spring mod, you get very little noise). It does make the little chirps if U crack the throttle then let off. Still make a little whoosh sound if U back off from full boost.

zx6r

Any chance you could list the pros / cons of the modified Greddy BOV compared to the SSQV BOV compared to the stock BOV ?