Ok so heres the rundown... I have a 2003 Lancer Evolution with 14k miles on it. I have a few modifications nothing serious though. I used to have a HKS SSQ BOV which was litterally the biggest peice of garbage you can imagine. It fluttered like hell and the bolt to turn didn't do anything at all in terms of making it go away. So I decided to go with a Forge Motorsport recirculating valve which I currently have in my car. (Keep in mind that I DO NOT vent to atmoshpere on any of my BOV's, I'm not stupid and I know its bad for the Evo). Initially I liked the Forge. It took me a while to get it tuned in but eventually I settled on the stiffest spring that came with it (blue I think) and I didnt use any spacers in it. Well I loved it at first. It flutter or anything when I shifted. I noticed however that when I would be going at speeds about 55mph when I would let off the gas really abruptly the car would flutter bad! I mean so bad it would jerk the car. However it ONLY does this at high speeds when you harsly LET OFF the gas. Needless to say this bothers me alot. Is there no BOV out there that will run perfect on this car? No fluttering, jerking or anything? The Forge unit is really nice except for this little issue. Sometimes it does this at speeds of about 20mph to but only if you really are flooring it and then suddenly take your foot of the pedal. Basically I am wondering if anyone else has this problem or anyone knows what I can do about this. I am running around 22psi so the stock BOV isn't going to work for me.

Any help is appreciated!
Chris Jumonville

 

If you floor it and let go of the gas and it flutters, that usually means your spring is too hard. If you floor it and let go of the gas slowly and it flutters, thats normal.

I currently am using the Forge BOV with the yellow spring in without spacers and it has been running great.....You might want to try that. If yellow is a bit too soft for your 22psi, you might want to add one spacer......

Hope that helps!!

 

That is what I was thinking that maybe it was to stiff. I have heard that fluttering period is very bad though and you mention that it is normal if I let of the gas slow and it does it?

 

Ok to my knowledge, when BOV flutters when you floor it and let go, its called a compressor surge, which is very bad for the turbo......No BOV should do this.......

My car does not flutter at all if I let go of the gas all the way (it just makes one big whoosh) however it does flutter when I let go of the gas slowly........

Many other people I've known to use Forge also has the same symptoms as me.....

 

Greddy Type S works perfect and made for the EVO...

I recommend this BOV... Minewas installed by Road Race Engineering in SoCal

 

Just tighten down the all the hoses connected to the STOCK BOV and run it! It may be plastic, but it still holds boost. I use it for a consistant 21 psi to redline.

Why do people always insist on getting a BOV anyway? I cant believe it can be called an upgrade, more like a swap. Just like on the WRX, the stock BOV was aluminum and held upwards of 25psi. The EVOs stock BOV is also capable of holding good boost. If you want the exhale sound all ricers love, just get an open element.

 

Yeah I still am not sure why so many people are willign to sacrifice drivability for some little sound. How stupid.

 

well i can get even the stock BOV to flutter.....

 

Supercharged GTZ - you might have your stock BOV mounted backwards. A friend had his stock BOV fluttering and that was the problem.

The Greddy Type-S and the Turbo XS are both good when you are pushing higher boost. I am sure there are more out there.

 

Leave the blue spring in!!!
I had all kinds of problems with the forge unit in the beginning. I used every damn spring/shim combination possible and it still fluttered. I called Tom at Forge and also heard from a few other people with the same problem that if you flip the valve around to where the vac. nipple is facing up towards the radiator hose the problem will go away. So I flipped it around and sure enough the damn thing works GREAT! I found that with it like this it needed to have a somewhat stiffer spring in it because it was opening a little too early. I have found the blue spring to be the best with it in this position.
If you must get something else get the Greddy Type-s, remove the smaller of the two springs in the Greddy, and tighten the adjuster on the top to about 5-8 threads coming out the top of the valve.
Both of these valves in each setup will work great!
Good luck.

 

Forge DV on my evo and Greddy Type-S on my girl's WRX with no drivability losses. Both sound great. Just a little is in order.

 

I am running the TurboXS now....but with the stocker, going up a hill in 5th gear, boostin about 10lbs, and slightly letting of the gas, I can get it to flutter. It is installed correct. I was thinking of lubin up the TurboXS though after reading about the piston seizing inside the BOV.

 

People (smart people) upgrade their BOVs because when you up the boost, the stock BOV spring can't keep the valave shut and you end up actually blowing the valve open. Now you can run 21-22 psi on the stock BOV, but all that's doing is making the turbo work harder to overcome the pressure loss, and heating up the air more. I think the Type-S is the best bang-for-buck valve out there.

 

For those of you that have BOVs with two vacuum nipples on them, like the GReddy Type-S, are you hooking up both nipples, or just the top one? Where are you plumbing the second nipple to?

The second nipple is a helper port that helps get the valve off its seat. You need to hook it up to a pre-throttle-body boost source. Best way to do it is to drill a hole in an upper intercooler pipe, tap it, and thread a hose barb into it. That is, if none of the boost sources at the throttle body are pre-throttle-plate. If one of them is, you can tee off of that.

To get perfect sealing, and perfect BOV operation when you let off the throttle, you can hook up a vacuum solenoid to a WOT switch. Let that port see atmosphere at WOT, and pre-throttle-body boost at all other times.

Personally, though, I dump all of those aftermarket valves, AND the stock valve, and just go with a 1G DSM valve. It works great.

Then do this to it:
http://www.thedodgegarage.com/turbo_bov_mod.html

to add that second port I was talking about.

 

greddy type s with the smaller spring taken out works great. no fluttering. Leave the little nipple unpluged. That is for running it VTA