It's the piston design of the new pistons. It is not actually fluttering but just the way the air is escaping. I presented all this to Forge already, I am waiting for them to get back to me.
One solution is to port out the inlet/outlet of the valve to allow more air flow. I had the old piston design so I went back to that to fix mine. Another possibility is to take the new style piston and trim down the ribs on it to allow more airflow.

See this thread for more information.
https://www.evolutionm.net/forums/sh...641#post405641

Basically it is like surge because it can't relieve the pressure due to a lack of airflow.

 

Not very happy with the Forge bov. Have had many and plan on scrapping this! All I know is that I am tierd of fussing w/this $170 part that sounds like it could damage my turbo seals. Anyway, I have had it on my car for about 2 weeks and am planning on purchsing the HKS sequential w/the recirc. kit. I have had many imports including cars imported directly from the motherland and this is a headach to use. All I can say is that it looks great but is a pain to adjust. You souldn't have to pull the whole valve apart to adjust the spring tension. I hope they can fix this problem! I am not bashing thier products, simply giving some advice.

 

Im trying to be the dumb a## but what is BOV?

 

B=Blow, O=Off, V=valve

 

Just so I understand correctly it is fine for the BOV to have a slight flutter under 5 psi. Just want to make sure nothing can be damaged?

 

actually I just went for a drive and I get flutter at about the zero bar mark and below but not much at all after that. I still have the same question as above.

 

Hey all-

Just installed my Forge d/v (new piston design with the ridges). It does not flutter until I give it more than 1/4 throttle and let the boost start gaining around, oh, 2800rpm. The fluttering does happen at part and full throttle if I shift before 6500rpm or so. At WOT to redline, it makes a solid "PSSSHT!!" sound, but it has to be totally wide open. Any partial throttle (i.e. less than max boost at that RPM) is going to cause the flutter.

I think the flutter is normal, I am happy with this thing so far. I have an HKS RS so it makes a TON of noise, good lord. I love it though. I am going to play with the springs/shims to see what I can accomplish. The valve holds strong to redline right now, but I'm pushing stock boost with no boost gauge so I can't give you any hard numbers.

FYI I am using the yellow spring right now which came in it.

Does anyone know the size of the hex bolts on this thing? I can't find a damn thing to fit them.

 

this thread was very disturning to someone who was considering upgrading the stock DV to the Forge...

what are our other options for a DV...?

 

Actually it does do something for the evo. I have installed three of them, one on my car and two on customers cars we all had the sam impression.. boost comes on quicker especially at part throttle or transitioning from crusie to wot.

 

Boost definitely comes on quicker, turbo spools a bit sooner. I need to do some more testing before I decide on what spring/shim combo to go with, but I'll report it back here.

Diesel, install the thing, it's great it just takes a little tuning if it's not right the first time around. No big deal, that's part of the fun!

 

OK after a bit more test driving today, I have decided that I _AM_ getting a flutter at WOT all the way to redline. It appears to be that I shift too quickly to let it flutter more than once or twice when I'm really hauling the mail (heheh not a bad thing of course) but previously I couldn't hear it.

I will be fooling with the other springs and shims and probably cutting my vacuum line to fit better (it's a bit long but AFAIK isn't crimped). Vac line first, test, then if necessary I'll open her up and test some different springs etc.

 

I just put the stock one back in and my car goes great now. The Forge i have causes a huge stumble when letting off after building partial boost. If this is the flutter everyone is talking about, it is totally unacceptable and not a normal condition. An aftermarket RV should not cause any driveability problems. I emailed Forge twice and they have not responded at all.

Peter

 

Peter, you need to play with the springs/shims to get it right. Every car is different especially with different mods and such. The Forge does its job well it just needs to be tuned.

I put my stock one back on today for an autox event and will be swapping springs tomorrow. I've got it down to about a 5 minute swap job now.

 

Funny I don’t have the problems others are talking about. Do I have a little flutter every now and then? Yes, only every once and a while when letting off under moderate cruise at about 0 vac. Under full boost I've never had a problem one... other than it is obvious that the Forge DV holds boost better than my crappy OE. Makes me wonder what spring was shipped with my valve, as I've never had it open. Then again I'm only running a Works P1...