IspyEvo

I picked up my evo 8 a little while ago, all stock except BOV and i have no idea what kind it is...

as soon as i put on my buschur airfilter kit i noticed a big difference when i shift or let off throttle on low boost i get this flutter sound, but when im actually boosting higher the flutter isn't as noticeable anymore and instead i get a loud BOV sound

im worried that its is turbo surge and i searched around with people telling me its is surge or its just the bov

Imports14life

It's a little of both...First step, find out what blow-off valve you are working with. Quality and reliability are important with critical parts like blow-off valves...

"Blow-off valves are used to prevent compressor surge, a phenomenon that readily occurs when lifting off the throttle of an unvented, turbocharged engine. When the throttle plate on a turbocharged engine closes, the high pressure air in the intake system is trapped by the throttle and a pressure wave is forced back into the compressor. The compressor wheel slows rapidly and may even stall, and the driver will notice a fluttering air sound."

What you are hearing is indeed compressor surge, to some degree. Being as you are not under full boost, and the blow-off valve does not have the required vacuum to open fully, so some of that air is making it back to the compressor. I believe it is generally accepted that you will have some degree of compressor surge at low boost, so I would not worry too much about this problem, as long as your blow-off valve continues to work under full boost. As far as mitigating the sound you are hearing (if you so choose to do so), you could attempt to loosen the spring in your blow-off valve, if it is accessible and adjustable.

Hope this helps. I am by no means an expert and would advise you to research your particular blow-off valve and to ask others if they have had these issues like yours as well.

evobros

iTrader: (25)

im having the same problem with my stock 9 bov??? i dont know y

bbyevo8u

iTrader: (14)

i got this problem after i crushed my ix dv, loosen the spring if you can

Berts24

iTrader: (3)

I some times get a flutering sound on my stock 9 BOV it only really happens when it's really cold out

IspyEvo

yeah the only problem is that i bought the car with the bov already installed and have no idea what kind it is, cant find any names/markings. its not on my uicp and its a dual vent.

4G63kevin

iTrader: (16)

I'd recommend selling that bov and get the IX MR valve or if you've a crazy setup, run tial. gl!

EvoIX Beauty

i'd suggest checking the spring in the BOV since that will help determine everything. or look into getting a different one since you don't know much about the current setup- one of the first mods i did was get a tial BOV and i've had to play around with the different sized springs. i just love the sound of my tial!

SyZyGy1394

iTrader: (4)

What lb spring do you have in it? I first had an 11lb and it used to flutter-dump a lot, so I traded it for a 9lb spring. I don't know why, but ever since I changed the o2 housing it seems to flutter-dump again.

IspyEvo

okay so i took some pics of my bov hoping someone on here will recognize it or be able to identify it haha



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Svendiesel

iTrader: (25)

Do a boost leak test.

Any form of a leak in the system will instigate part throttle flutter. Check vac lines too for sure. I had a few very minor boost leaks, for example, from my alcohol nozzle. I tightened up the nozzle, the seal got much better, and part throttle flutter was completely eliminated.

IspyEvo

Bump
for some help

4WS Tuning

iTrader: (73)

Thats a heavy duty bov... If you have more than just the spring installed it could be surge...

I suggest swapping that out for a recirculating bov like the synapse. You'll have much better luck with it and won't have to worry about problems like this.

I would also invest in a tactrix cable so you can pull the map. Many guys demod the car then trade them in without considering the next owner. As far as you know the cars tune might be WAY off making it drive badly.

PM me if you want some ideas of where to start.

Cheers!

OneEyedJack

iTrader: (6)

It is DEFINITELY surge. This exact thing happened to me. Get a metal IX valve and RECIRCULATE IT.

EvoIX Beauty

can't remember exactly what lb spring it is, but i want to say its the pink one - i tried all of the springs that came with the tial and had the same flutter issue. i've got an invidia o2 as well and since i don't want to get rid of my tial(since i sold my stock BOV in exchange for the tial), i'll probably change the speed density cuz i'm still deciding on mods for this year