Have it with no problems... wondering if it is not a quality control issue.

 

Yo Silversurfer.....thanks for all the info you posted...it helped me out a lot...just got my Greddy bov installed, and told my friend to take out that little spring.....and it runs real smooth....thanks again and feel free to post any other things you know about...

 

The 1g BOVs do have an assist port. It's that little hole on the bottom. It runs up the side of the valve body to the bottom of the diaphragm. I tapped threads and installed a setscrew w/ blue loc-tite in the hole on the bottom. Then drilled a hole in the side of the port. This prevented vacuum or pressure build-up on the bottom of the diaphragm. It allowed me to run over 18psi. With high boost applications, the problem was not holding the pressure; the valve is physically too small to permit proper circulation in-between shifts.

Don’t forget, you want to keep that turbo spoolin!

Did that make sense?

 

I have the greddy tybe S, and I couldn't figure out why the bov flutters. also the car would drop down to 500/400rpms when i came to a stop. so tonight i took off the lil spring inside,and everything works great now. no more rpm dropping below idle,and no flutter. it did take away the ninja sword sound, but i don't mind. Thanks SilverSurfer

 

so you only took the small spring without adjusting anything else on the BOV right?

 

i turned it in about half way of the needle.i had it out to far the first time, and it would blow off before i wanted to shift(around5-6k).but the more i turn the needle in the more it held.

 

Here is a pic of how RRE sets their's up for the Evo.

 

Here is a pic taken from the airbox side:

 

Wow....I thought the evo wouldnt have a problem with a vent2Air...damn...the pshsssssssssssssssshhhhhtt.. is so nice though serves no purpose

 

Thanks for the instructions; my stalling issues are ALL GONE!!! Smother than stock with this spring mod. The Greddy Type-S sounds much better too...

I wanted to add that my car holds boost just fine with this BOV mod. I am running ~20.5 - 21 PSI. There was some talk that you should not do it for higher than stock boost levels. I tested it for a few runs @ 23PSI and it seems fine. I don't run that much, but I thought I would give it a quick test. I have hesitated trying this due to the boost level discussions. I wish I had not waited.

Chris

 

I am glad that you like it, and yes the BOV will not leak at 21 PSI or even much higher. I don't believe that boost tappering at higher RPM has anything to do with the BOV leaking. I think those that have reported BOV leaking were simply looking at boost tapper and assumed it was the BOV leaking.
There seems to be an inherent boost tapper at high RPM with the stock EVO turbo system, I think it is caused by flow restrictions and/or the stock waste gate actuator.
I know that with free flowing intak/exhaust and cams, the boost tappering at higher RPM is much less of an issue, especially in cooler weather. That is part of the reason they make more power.

Think about it for a minute, the actuator has a larger surface area (greater mechanical advantage) with virtually the same pressure pushing down as the valve has trying to force it open, plus a 12 pound spring tension. How could it possibly leak? Based on my own testing I can tell you that it does not leak and logically it cant.

There are a lot of misconceptions out there regarding BOV's leaking, and even some authoritive individuals seem to buy into this. Maybe they are just trying to sell BOV's I don't no.
If it weren't for the poor seal caused by the plastic on plastic stock valve, plus it's not adjustable. I would never have even replaced the stock valve even for much higher boost levels. The only good reason to upgrade to a larger BOV with a big turbo is for more flow venting which would prevent surging with a larger turbo air flow.

 

Thanks for all of your input, it really helped me and I am certian many others. I have to get used to my "new" EVO... The smoother and more "friendly" EVO...

 

Your welcome.

I have a couple of new tips;

As you may know I recommend running with the adjustment screw almost all the way out. A couple of weeks ago I was on the dyno and just for kicks I decided to try cranking the adjustment screw way down to see if it would improve response. It did not, nor did it affect the boost in any perceptable way but it did have one side affect, at idle the valve started to whistle. I had seen some people complaining about this, now I know why.
With the one large spring and the adjustment screw most of the way out, the valve is slightly open at idle. With the adjustment screw turned in the valve is on the edge of open/close at idle and begins to resonate/whistle.
This made me realize why a lot of these aftermarket BOV's usually intended for VTA, use such high spring tensions. It's not for boost leaking or neccessarily better response. With out all that spring tension the valve will open at idle and part throttle lifts. Under those conditions you would need to put some sort of filter on the valve outlet otherwise you will would contaminate your your engine running VTA. A filter on a VTA BOV would inhibit it's venting efficiency, so what do you do? Lot's and lot's of spring tension.
Keep in mind that at light part throttle lifts the engine will create even higher vacum levels and the entire intake system could also be under vacum, so it's not just at idle were the valve would be open. They need enough spring tension to keep a VTA BOV from opening under these conditions, or put some kind of filter on the BOV outlet, or just run it in recirculation mode like we do. In recirculation mode you don't need a lot of spring tension, only for unfiltered VTA.

This makes me realize how critical the spring tension adjustment is for a VTA BOV. You need enough tension to keep it closed under all intake vacum conditions (idle, part throttle) but you want it to open under manifold vacum/turbo boost conditions. Proper adjustment would be a very fine line and for safety most of the aftermarket valves use higher than needed spring tension to prevent engine contamination, but then they also surge a lot more than you would like. This is why that BOV test done by turbo mag a while back showed most of those aftermarket BOV's with a lot of surge.

 

Although I am new to the EVO world, I used to drive a WRX, which seem to be as particular about BOV use as EVO's are. On my Subaru I ran a WorxTuning (not to be confused with Works Rally) Dual Stage, which despite the typical aftermarket bov disputes, has proven itself time and again to perform flawlessly on the scoobys. I ran one on my car after trying a couple of other brands that proved to be no better than stock, and was super impressed with its lack of drivability issues and decrease in spool between shifts. So when I got my EVO, I decided to do a few mods, one of which is to be a bov. I am not a ricer in any shape or form, but after my experience with the Worx Dual Stage, I was sold on its benefits. It is very tunable as to how you would like it to function, and probably one of the highest quality parts I have bought in my 20+ years modifying cars. Anyway, to end my longwinded post, I called them to see if they had any plans to release a Dual Stage for EVOs, and to my surprise, they just came out with it last week. They said it has been undergoing tests for the last 7 months and have found it works just as well if not better on the EVOs. I ordered one so we'll see, but I have no doubts it will be awesome. If you want to see one or read more on them, go to www.WorxTuning.com . I will let everyone know how it goes.

 

This is a good write up with nice pics, describing the type S with the same modification I posted at the begining of this thread. The test data also matches with my own.
I don't know who they are, but whoever made this, nicely done!

http://www.evomoto.com/tech_info.php?techID=28