Fluttering stock BPV

N

NYXphil13

Member
So after the addition of a PG fmic, I'm experiencing some flutter from my stock bpv. It seems to happen most frequently if I step on the gas but shift a little early...probably around 4 grand. If I drive WOT up to 6k rpms, it doesnt flutter. Sounds like its only happening when its under load. Whats going on? The additional mods are: Cobb AP, Corksport Catless TBE, Cobb sri.

On a side note, I have ptp internals and some spark plugs on the way...what should the Denso's be gapped at? Im hearing everything from .26 to .30 with the AP.
 
I have the turbosmart bpv and I have experienced the same thing after my PG FMIC install. Did you use the little 90 degree bend tube for the recirculation hose? I think that might have a lot to do with it
 
With increased airflow and their weird 90* tube, make sure you aren't getting compressor surge from the recirc tube not adquately releasing the air back into the intake track. Is the flutter coming from the turbo area or up front where the BOV is? Find that out, if it's from the BOV, then it might just be acting funky with that 90* but if its from the turbo you might be getting compressor surge, which obviously is bad.
 
I don't think there would be initially. It's just a lot of stress on the turbo, with the air not being released adequately at the same time outside air is being pulled in you get a problem where the two currents collide causing the increased stress and sound.
 
I wish I could tell where its coming from. I can only re create the noise when im driving and its tough to tell exactly where it is from the drivers seat.
 
Call PG about it maybe? or if you have the cash have any local shop with a dyno put it up there (if you have any) and they should be able to replicate it there and take a good listen.
 
inadequate release of pressure from the BOV/BPV, basically the function of the BOV is to recirculate or vent all the built up pressure left in the system after the turbo builds boost pressure. if that 90* kinked recirc hose is possibly causing a turbulence in letting the air recirc correctly that might be the cause. essentially any pressure not vented pushes back against the turbo in the opposite direction that incoming air is pulled in, causing the turbine to have to battle both ways, it stops and starts and stops and starts and causes that flutter sound.
 
Flutter sound only happens at part throttle for me. When moderately accelerating or at WOT the bpv is a nice choked tight air sound, no flutter. Would there be flutter all the time if it was a compressor surge issue?
 
my hks ssqv does this some times too when i let off part throttle and im VTA, im not worried about it
it happens when boost pressure increases as you let off, but not enough vacuum is available to pull on the BPV/BOV to vent the pressure, thus causing minimal compressor surge but more so for the valve to flutter open
 
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My ssqv always flutters at part boost its the sequential design, it's known for it. but i dont know of any other valve that does it, the hks flutter isnt compressor surge
 
SallySpeed3 said:
Flutter sound only happens at part throttle for me. When moderately accelerating or at WOT the bpv is a nice choked tight air sound, no flutter. Would there be flutter all the time if it was a compressor surge issue?
Click to expand...

you would probably hear it all the time if it were compressor surge, if its only at part throttle normal driving i wouldnt worry too much about it
 
Flutter is okay, my Turbosmart does it all the time, usually if I'm in high gear and I boost and let off it will flutter, it really depends on your perticular setup, if I have the BOV spring to tight it will cause bucking when you let off the gas, to loose it doesn't seal propertly and will "ping" everytime you step and let off the gas caused by the piston being pulled to easily by positive Hg's. SURGE is BAD ( sounds like a turkey) spring waaaaaay to tight.

On the Denso's that depends on which one your using 20 or 22? I have my 22's set at .028 and no problems. my 20's are set at factory .035

NYXphil13 said:
So after the addition of a PG fmic, I'm experiencing some flutter from my stock bpv. It seems to happen most frequently if I step on the gas but shift a little early...probably around 4 grand. If I drive WOT up to 6k rpms, it doesnt flutter. Sounds like its only happening when its under load. Whats going on? The additional mods are: Cobb AP, Corksport Catless TBE, Cobb sri.

On a side note, I have ptp internals and some spark plugs on the way...what should the Denso's be gapped at? Im hearing everything from .26 to .30 with the AP.
Click to expand...
 
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If your getting COMPRESSOR SURGE, then turbo or engine will go BOOM! Cause of it is the result of an excessive increase in the resistance of the system while the compressor is operating at a certain speed. A decrease in the mass flow rate or an increase in the rotational speed of the impeller. either way you dont ever want to experience it, most after market turbos now have anti-surge ports built in to the housing to maintain positive PSI build while reducing risk of "boom"


NYXphil13 said:
if i am getting compressor surge, what would be causing it?
Click to expand...
 
spdjnke said:
If your getting COMPRESSOR SURGE, then turbo or engine will go BOOM! Cause of it is the result of an excessive increase in the resistance of the system while the compressor is operating at a certain speed. A decrease in the mass flow rate or an increase in the rotational speed of the impeller. either way you dont ever want to experience it, most after market turbos now have anti-surge ports built in to the housing to maintain positive PSI build while reducing risk of "boom"
Click to expand...

you wouldn't necessarily go boom immediately. but yeah it will definitely speed up the process. too bad our turbos arent aftermarket, lol.
 
thanks for all the info guys, it just seems like im getting the little flutter thats not happening frequently enough to worry about...just havent really heard an ms3 with a stock bpv flutter
 
Reason being most people with a FMIC goes aftermartket, If I'm not mistaken your probably the ONLY one that I know who is running stock BPV on FMIC.


NYXphil13 said:
thanks for all the info guys, it just seems like im getting the little flutter thats not happening frequently enough to worry about...just havent really heard an ms3 with a stock bpv flutter
Click to expand...
 
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