I have the Forge DV on my VIII and it has the infamous flutter. I have all the basic bolt ons + GSC S1 cams and even with the stiffest spring (red one) and shims it still flutters at partial throttle around 5K rpm.

I tolerated it now for a few months, but I've been growing increasingly tired of it not holding up under partial throttle. My question is if I change it out for the stock IX or a similar DV will I still get the flutter under partial throttle or am I stuck with it for life!

 

Is it installed backwards by any chance?

 

Nah, it's definitely in the right way.

 

tried a less stiff spring?

 

Yeah, tried all of them with pretty much the same result. The stiffest one is the best of them all, but still not completely right.

 

Use the softest spring to get rid of it, not stiffest.

 

How would the soffest one fix that? Wouldn't it be prone to open easier?
I'm not trying to argue or anything just trying to understand.

 

The stiffest makes it harder for the excess charge to exit out the valve causing it to flutter. The softer spring will alleviate your problem but you run the risk of causing the valve to leak boost pressure. Some flutter isn't a bad thing. Even my stock 9 DV flutters at partial throttle.

 

Basically a soft spring will open at a smaller pressure differential (between your turbo outlet pressure and your intake manifold pressure) and therefore flutter should be less violent of an event.
It's very tough to get rid of BOV flutter altogether when you have a small turbo that builds a lot of boost at part throttle. Internal WG can't relieve the turbo pressure, so the excess has to come out of your BOV. That's why your problem would go away with a plastic VIII bov - it simply starts leaking early

So either use a leaky/soft spring BOV, which isn't too good if you are trying to make high boost (like over 25psi) because you will overwork the turbo; or learn to drive around the issue. That's what i had to do

So thats my take on it. I'm a Forge RS user FWIW.

 

I tried the soft spring and it is less violent, but it obviously does just dump everything instead of the flutter. I guess it is a choice of how you want to live with it.

Thanks for the info guys. I do like the Forge, I mean it holds boost awesome at wot. I have been putting up with the flutter and have adjusted my driving, just wanted to see if there was any way to completely get rid of the flutter.

 

how much are you boosting? if it's 24/25 ish or under, get the IX bov... i don't recall hearing anyone with fluttering issues, plus it's the best bov for those boost levels/under...

 

I have a small collection of DV's - OEM, IX/MR, and the Forge. I put up with flutter for way too long.

I finally broke the piggy bank and went with the APS DV/BOV per recommendation of Mellon. This is by far the best; it holds 28 psi and no flutter.

 

^^ 33psi peak here, no problem...in fact I let it zing to 40psi once

 

i just purchased the 1G forge replacement DV cause i have the buschur racing upper intercooler piping. Its annoying as hell. I believe it has the yellow spring in it that it came with, with no shims. The valve actually flutters during shifting?? and the partial throttle sucks.

the 1G crushed valve also had some fluttering at partial throttle in 4-5 gears.

So any suggestions for what shims or spring to use?

Thanks

 

I use a Synapse Synchronic and with the almost infinite adjustability of it I was able to very nearly eliminate all flutter. Very slight if I induce it intentionally. Since it has a boost reference and a vacuum reference if it does open at the soft setting I have it on, it is so little that you can't tell. In order for me to induce flutter I have to be in 5th gear less then 2500 rpm and make some throttle inputs that I would never make in normal driving. Let me know if I can help you in any way.

Josh