BOV flutter?
Sounds like you're experiencing compressor surge (which is one of the worst things your turbo can go through. Your turbo stops spinning the normal way, and abruptly spins the other way), that isn't the BOV making that noise.
The flutter is back pressure against your turbo, which spools it backwards. This is very bad. I experienced this sometimes in my old evo with a turbosmart dual port.
If your driving around town and the such, try not to hit boost. Of if cruising on the highway. If you do hit boost, Just step on it completely for about a second so all the boost builds up, and let it go, to release it. The backpressure is killing the turbo.
Or, Buy a softer spring if available for your BOV.
Just my .02, based on my knowledge. Correct me if I am wrong about the softer spring, because there might be the possibility of it opening up during WOT if its to soft, and the boost going out aswell, :P
If your driving around town and the such, try not to hit boost. Of if cruising on the highway. If you do hit boost, Just step on it completely for about a second so all the boost builds up, and let it go, to release it. The backpressure is killing the turbo.
Or, Buy a softer spring if available for your BOV.
Just my .02, based on my knowledge. Correct me if I am wrong about the softer spring, because there might be the possibility of it opening up during WOT if its to soft, and the boost going out aswell, :P
over exaggerating a little bit there buddy
to everyone sitting here saying what COULD happen, have you ever seen it happen? cause ive talked to a lot of well known shops and not one of them has ever reported something like what is being said happening
i been daily driving my evo for over 2 years with an upgraded blow off valve which would cause it to flutter all the time. not one thing has ever come about the flutter.... my turbo is completely fine as is the rest of the car
Last edited by EvoJoeIX; Feb 27, 2010 at 03:22 PM.
Compressor surge is something that will happen period! you can't completely get rid of it. You can however by getting the proper bov cut down on the amount of surge. Compressor surge is not when the turbine spins in the opposite direction. it's actually the slowing down or stahling of it. yes it tends to be worse with a VTA BOV but that's just the nature of the beast. Even if you go speed density you will still have surge. honestly if you really wanna know what compressor surge is and what it does, I would google it. You need to post threads like this to find out what it is. then search so you know exactly what ur dealing with. You will honestly never get a straight up answer here. That how i do it. My explanation is a short one, but you would benefit from looking more into it!
Last edited by VIIIrs; Mar 1, 2010 at 05:48 AM.
Compressor surge is something that will happen period! you can't completely get rid of it. You can however by getting the proper bov cut down on the amount of surge. Compressor surge is not when the turbine spins in the opposite direction. it's actually the slowing down or stahling of it. yes it tends to be worse with a VTA BOV but that's just the nature of the beast. Even if you go speed density you will still have surge. honestly if you really wanna know what compressor surge is and what it does, I would google it. You need to post threads like this to find out what it is. then search so you know exactly what ur dealing with. You will honestly never get a straight up answer here. That how i do it. My explanation is a short one, but you would benefit from looking more into it!
BTW the wastegate is not for stopping flutter sounds either. It controls the speed of the turbo so it doesn't overspin. It bypasses the exhaust gases once desired pressure is reached. Some open and some closed. 
I have the same sound on my stock DV and I think every evo does, you just can't hear it, I have a mod to my lid so I can hear it clearly. It's normal, won't damage anything, and BTW someone said it will damage the bearings (I suppose turbo bearing) well our turbos don't have those.
Last edited by biggie5252; Mar 3, 2010 at 09:52 PM.
