Hello everyone.

I just picked up a very nice 08 GSR with 45k miles last week, the car did come with some nice mods, nothing crazy though.

One of the mods though was an Agency Power BOV. I listed a picture my engine setup below, car also has full exhaust with high flow cats, grim speed manual boost controller and is tuned on 25 psi done professionally at a tuning shop.



Now I also want to add this is my first turbo car so maybe what i'm hearing is normal? Maybe not lol.

My problem is that when i'm in 4th or 5th gear and give it gas/ left off the gas in low RPMS, I end up getting a fluttering sound and im assuming its coming from the BOV? For Example im on the highway in 5th gear at 2-3k rpm then left off the gas because someone is infront of me, I get a fluttering sound and it kinda scares me, the car doesnt buck or anything but I wasnt sure if it was normal. I also saw the BOV has an adjuster knob on the top of it and I have no idea what that does either so I didnt mess with it.

Also if someone could explain what is the cause of this and a way to get rid of it or suggest another BOV that wouldn't have this problem would also be helpful.

any help / suggestions would be greatly appreciated, thanks guys <3

 

Bump

 

This is normal, and common with a lot of aftermarket BPV / BOVs. In my experience and based on a bunch of reading I did a while back, the stock BPV is the best for reducing the flutter at low RPMs / boost. I had a Forge DV that fluttered like crazy and made it almost impossible to drive in cruise control on the highway.

The only issue with the stock BPV is that it will occasionally not hold as much boost as an aftermarket model. Results will vary, I am doing fine with similar boost levels to you with the stocker. I'd suggest picking one up if you don't have it already and then logging to see how everything is running.

 

I get the same flutter with the stock BOV but I am running a bigger turbo so they told me it is normal

 

Compression surge.. Lol nah I wouldn't worry about it. Just sounds like a stiff spring and that helps with throttle response. As long as the flutter stays at low RPMs it shouldn't be harmful.

 

It's normal to flutter on the aftermarket ones if your only giving it a little boost as its set to hold the Max psi there running. I always had flutter with partial throttle let offs and it never hurt anything just not enough pressure to open all the way. If you loosen the stiffness you risk not being able to hold the boost anymore to where it's set.

 

I've seen plenty of threads where people are like.. dude that is compressor surge your turbo is about to go. Its just depends on the spring strength in the valve. Unfortunately when you get the right setting for holding the boost it flutters like crazy under low boost / low rpms.

 

its your bov. i have a forge bov and it does the same thing in 5th gear, as long as your bov doesnt do it in high rpms or high boost than you have nothing to worry about

 

Have had this issue with a Synapse DV and now a GFB 50/50 BPV.
The issue (in my experience) is the spring. Called Synapse when it was happening and they asked me to pull the spring and take a picture - turns out the put in the wrong spring for the "Evo X" model and sent me a new spring. Fixed the issue.
Bought a GFB Adjustable (50/50) kit because I wanted more sound (yeah I'm a giant douchebag) and had the same issue. Contacted their support and the actually sent me a prototype rebuild kit to test which also had a "lighter" spring - fixed the issue.

I would contact the manufacturer and tell them you are getting flutter at low RPM and suspect the spring is too heavy.