I currently have an APS Twin Vent on my Evo8 with pretty much all basic bolt ons and tune. I bought the APS originally thinking it would rid me of the turbo flutter sound im getting through the intake. Well I adjusted the screw up top and some how awhile ago the locking nut got lost. Since then I have replaced the locking nut and now just have the problem of how I should adjust the bov. I have noticed that the more I tighten the adjustment screw the more boost the car runs and vice versa when loosening the adjustment. When tightened though, the car seems to be more prone to partial studder when boosting from low RPMS in a high gear.

I have searched a lot of threads but came up with not much info. What are you guys finding are the optimal settings for driveability? I know a lot of people just left the settings alone from out of the box. Maybe if someone can explain the pro's/con's of having the adjustment screw almost all the way in versus all the way out? I have tried a few different adjustments and can't seem to find the "optimal" setting.

Thanks in advance!
Chris

 

Every car is different, but I run mine with two threads sticking out of the lock nut.

 

I'm wondering the same thing because I'm having the same problem. I get a lot of flutter when I'm in 5th gear and release the gas pedal at low rpms. I thought maybe it was a cold weather issue.

 

When I replaced the lock nut I had to buy a different one from a local hardware store. I actually had to buy a wing nut. How many threads are sticking out without the locking nut in place?

 

its stiffening the spring, of course it will flutter under partial throttle or boost. its the spring "bouncing" because of the lower pressure going through it. either leave the spring tight and enjoy good boost hold, or loosen it up and enjoy not having flutter but deal with it leaking under higher pressure(ie: drop in psi per rpm). boost flutter does not hurt, and you can always adjust your driving habits to work with the stiff spring setting in your BOV and not have flutter.

 

Actually an improperly setup BOV that flutters can induce compressor surge and that is bad for your car.

 

I guess it will be trial and error. I just adjusted to a pretty tight setting and will see how that will do for driving.

 

flutter is flutter

surge is surge

they are two different things all together

 

Is there any adverse effects from having the adjustment screw on pretty tight? I would say i have it about 3-4 threads sticking out of the top without the locking screw on.