Low boost compressor surge

[YoshiBishi]

I get a fluttering sound when <5psi. Anything above that is fine, BOV works normally. Holds 18psi without a problem.

The relevant parts on the car are:

3sxecutioners
GM MAF Sensor
MAF Translator
Dejon Intake Pipes
Turbosmart Supersonic BOV VTA

Some forums say that a bit of surge at low boost is normal, is this true for our cars? I may try to soften the spring first, but not sure if that will cause boost leak at high boost.

How do I tell if it is compressor surge or wastegate flutter?

Thanks!

[YoshiBishi]

Another note, if I keep the throttle open and hold it around 3psi, it "flutters" too. It doesn't just do this when I let off the throttle.

[RL7]

The open BOV probably has something to do with it. Can it be recirculated?

[YoshiBishi]

I can't tell if I can recirculate it, since the plump back on 3sx costs the same as the supersonic BOV itself. So I am guessing it's a completely different BOV.

I am also running blow through. I feel like it may be wastegate flutter, since it only really happens at low rpm/boost. However, I have no idea how to tell the difference between them.

I am having a hard ass time trying to find true wastegate flutter sounds on youtube =/. But it does not really sound like any of the compressor surge videos.

[ICPREY]

FMIC? Ray Pampena had a write up on 3si about an "equalizer" hose to reduce surge.

[mb3000]

^Yes, that would probibly help you. You might also notice that the car does it more during cold temps & when the engine is still somewhat warming up.

I know exactly what you are talking about, my car does it and it's annoying as hell.

[YoshiBishi]

So it is compressor surge and not the wastegate? I still have stock SMICs for now, going to get FMIC later down the line.

[VR4Drive92]

its a form of compressor surge. Usually caused by the intake events and the fact that the lengths of the induction path from each turbo are different. Each turbo essentially starts screwing with the other. This is where the balance tube comes into play. It allows relief of the pressure differential between the two pipes in a transient response.

waste gate flutter is actually rare. Most is just the off throttle compressor surge that happens at low shaft speeds and low engine speeds because the BOV can't open fast enough or have enough pressure inside it to actually correctly.

[Keyan]

The surging is happening because the turbos are fighting each other to build pressure instead of pushing through the gm maf honeycomb. My turbos do it at around 80mph in 5th at just about any throttle input except off and wot. I'll take a video. It'll bounce between 5 and 10 psi sometimes, and makes the weirdest noises...

[Droid X via Tapatalk]

[green-lantern]

I have the problem also. It got a bit better with some tuning but it’s still doing it. I usually get it on a slight incline right at the point of = pressure in the plenum. I thought about putting in a tighter spring in the BOV but I’m not sure it will help more than hurt. I’ve also thought about putting in the equalizer tube between the piping.