bov question

[Dert]

So with my t25 my greddy type rs released the normal "woosh" sound at all boost levels, now since changing to a big 16g, under low boost it emits the same sound but under full boost it almost sounds like flutter but not compressor flutter its more like the vavle opens and shuts repeatedly, kind of like how some supras sound on youtube videos. Anybody know if this is a normal charactoristic of the type rs? Like I said it never did this at 15psi with the t25 but 15psi with the 16g it does.

 

[BIRDCLAWTSi]

How did you set it? Did you use a vacuum gauge?

 

[Dert]

i left it set the same as I had it before, should i tighten it maybe? I have maybe just over an 1/8" left to screw the adjustment screw in. I have a punishment racing type s knock off, but when i threw that one on with the t25 it seemed like a pile of sh*t. I'm thinking maybe this greddy cant handle the wrath of the 16g time for a tial

 

[2gjlc]

If the BOV is fluttering it usually means its adjusted to tight. I had the flutter problem with my Greddy Type S. You want to adjust the BOV as soft as possible while still being tight enough to hold the boost you want. Also if it is too tight it can cause compressor surge.

 

[BIRDCLAWTSi]

The proper way to set the bov is to take a vacuum gauge and pump it to 20" and loosen the screw until the valve just starts to open. That way it will be open at idle and on quick decel you wont stall. If you want to tighten it past the point of that you will have to pull fuel to make up for the lack of air due to the bov being closed.

 

[2gjlc]

Wouldn't you want the BOV to open sooner than 20? I know even before I had cams I would only get about 18 or 19 in/hg of vaccum. I would think like 17 would be a better number to shot for. Im not sure but can you enlighten us as to why 20?

 

[Dert]

If the BOV is fluttering it usually means its adjusted to tight. I had the flutter problem with my Greddy Type S. You want to adjust the BOV as soft as possible while still being tight enough to hold the boost you want. Also if it is too tight it can cause compressor surge.

But if it was too tight wouldnt it make the same sound at low psi? If i only boost 5-10 psi it opens normaly, but under full boost 16psi, it flutters, now if was too tight, why would it be able to open normaly under low boost and not high?

and the flutter isnt the usual air blowing back through the compressor flutter it more like the valve is openening and closing really fast, I loosened it off but got no different results except the fact that it doesnt hold boost backed off

 

[BIRDCLAWTSi]

20" is idle vacuum for my 1g. But you are correct, You would set it to whatever the idle vacuum for your engine is. Basically , You want it to open at idle, If it doesnt, . When the air that is supposed to come out of the bov at idle is not there, It messes things up. The ecu will continue to compensate for the air whether or not it is there. You can compensate for it with an AFC or whatever you are tuning with(Removing fuel) but i had an issue where it would stall. You may want to set it a little tighter than that but mainly you dont want surge.; I am not refering to the light flutter you may get at low boost, Part throttle. I am refering to the flutter/ Surge you get at full boost. You can actually stall the compressor and destroy the turbo. Here is a link to the single spring mod the evo guys are doing. I have no experience with this method but it is an option.
Evo Moto - Evolution 8 / 9 / X Performance Parts

 

[Dert]

20" is idle vacuum for my 1g. But you are correct, You would set it to whatever the idle vacuum for your engine is. Basically , You want it to open at idle, If it doesnt, . When the air that is supposed to come out of the bov at idle is not there, It messes things up. The ecu will continue to compensate for the air whether or not it is there. You can compensate for it with an AFC or whatever you are tuning with(Removing fuel) but i had an issue where it would stall. You may want to set it a little tighter than that but mainly you dont want surge.; I am not refering to the light flutter you may get at low boost, Part throttle. I am refering to the flutter/ Surge you get at full boost. You can actually stall the compressor and destroy the turbo. Here is a link to the single spring mod the evo guys are doing. I have no experience with this method but it is an option.
Evo Moto - Evolution 8 / 9 / X Performance Parts

my origional post states that it opens fully under LOW boost and makes a flutter type sound at HIGH boost, I never adjusted the settings on it since I had it with the t25, so if it had NO problems at all opening at 15psi on a t25 and NO problems opening at 10 psi with a 16g, why would it flutter at 15psi with the 16g? it makes no sense that it would be too tight at 15psi yet its not too tight at 0-10psi

 

[BIRDCLAWTSi]

I see what you are saying about not touching it, And the fact that it doesnt flutter at low boost but you are moving a greater volume of air with the 16G. Try backing it off a 1/2 a turn at a time and see if it helps. You have to play around with the adjustments till you get it right. You can always remove the recirc tube, Hook the vacuum gauge up, And start there. Allow it to open at idle, Then go tighter from there until you are happy. On a side note, I just fixed a decent boost leak at the adjuster screw on my type s. I had to put a little rubber o-ring under the washer before i tightened it up.

 

[Dert]

I see what you are saying about not touching it, And the fact that it doesnt flutter at low boost but you are moving a greater volume of air with the 16G. Try backing it off a 1/2 a turn at a time and see if it helps. You have to play around with the adjustments till you get it right. You can always remove the recirc tube, Hook the vacuum gauge up, And start there. Allow it to open at idle, Then go tighter from there until you are happy. On a side note, I just fixed a decent boost leak at the adjuster screw on my type s. I had to put a little rubber o-ring under the washer before i tightened it up.

but wouldnt the valve opening at 10 psi guarantee that it will open at higher boost? I mean it doesnt make sense that at higher boost its too tight but less boost its not...also on a side note I'm going to take the rubber o-ring off the P.O.S punishment type s knockoff and put it on my type rs just to make sure its sealed properly