Mike S

I have a stratmosphere adjustable CBV and I'm wondering how much I should be cranking down on the adjustment of this thing. I'm about 2/3rds the way down the thread and I'm still getting a "pffff, pffff, pfff" sound when shifting. I'm assuming from some of the threads I found that I need to crank it down some more. How many threads are showing on your cars? PS - I'm running 15psi.

Perry 951

Try backing it off. A little weaker spring rate may keep it from fluttering, but don't go too far or it can open under boost. You want it to have a smooth flow until almost all the boost is blown off, then a little flutter.

Asarus

Talking about CBV, do you think the stock CBV (or the 993 replacement) can be enough for a 15 to 17 psi usage.. ?

I'd like to keep my stock (or 993) cbv... but i wonder if i don't loose a bit of performance with it... :/

Perry 951

I blew out the diaphragms on 2 new valves in a short time running 18psi. It's worth buying a good piston style valve if you up the boost.

Matt Sheppard

I just blew my 993 part in my chips-only car. I'm not sure what does it, but these valves sure go quick. I'd say the Forge valve deserves a look. Any users comments?

Mike S

Well, for some reason I can't get it to not give me that "pff, pfff, pfff" sound when shifting or letting off the boost. I cranked it down all the way and then loosened it up all the way. Both had the same results. Do I need a different spring? I can't see how this valve could be torn since its all metal really. I will say that cranking it down all the way seemed to give better performance though. I think I have a good 993 one sitting around somewhere...I'll try that one tonight.

David Floyd

Are we talking about a different sound than the normal sound in between shifts when you have removed the stock airbox ?

Mine makes a Chhhhhh Chhhhh and rather loud when the windows are down, I have the Turbonetics Monster blow off.

Mike S

Yeah...that's the sound and my airbox has been removed.....but I was under the impression that the sound was caused by the boost pressure hitting the turbine blades of the turbo and forcing them to go the opposite direction. Is this sound normal?

If so, how loose can I go with the adjustment then? Does the boost spike after I let off if its too loose?

David Floyd

I think you are just hearing the normal sound of the blow off/bi pass valve recirculating the the boost in between shifts back into the intake.

I can't help with the adjustment on your unit.

CarreraCup03

I have a Turbonetics Monster BOV .. mine sounds more like a Rooster .. but I am venting to the atmosphere.

944turbo

David Floyd

**** a doodle doo ??

I bet you draw attention

CarreraCup03

It is actually embarassing.

944turbo

GaryK

I also have the new Stratmosphere adjustable bypass valve and it too makes a similar pfft..pfft sound when shifting. It seems to work best on my car at about the middle setting. FWIW, I'm running a T04E at 16psi. Mike S - I don't think you're having a problem with the bypass valve.

Bill

Mike,

I have the Stratmosphere forge valve. If you want to try mine or just go for a ride to hear it, lets hook up.

Magown

I have to agree, you hit the nail on the head it is embarrassing and it does sound like a roster. I've been ridding around with a Godzilla BOV venting to the atmosphere for about a week now and honestly find myself not wanting to push the car into the boost when other people are present.

I'm wondering if converting it back to a CBV configuration and venting it back to the turbo inlet will muffle the sound to a respectable level.