Fluttering Sound During Even Boost

[SubieGuy4]

Recently went to COBB Stage 2 and I'm peaking at 20.1psi.

If in higher gears (where I can go mid-throttle for a good few seconds before getting through the gear) and I go mid throttle and boost to anywhere in the 10-20psi range I will hear a fluttering sound along with the air rushing sound of the turbo. What is this caused by and should I worry?

 

[Bluedemon_II]

Wastegate flutter, nothing to worry about. It's the back pressure of the engine attempting to open up your wastegate flapper. Nothing serious and its considered normal at some point.

 

[SubieGuy4]

Awesome, thanks. Clearly sounds much worse than it is.

 

[Bluedemon_II]

Awesome, thanks. Clearly sounds much worse than it is.

Install an External gate and you will notice it worse. It's kind of cool actually :tard:

 

[Undecisive]

Do you have a dyno graph showing your boost levels across the powerband? I'm trying to figure out how long it's spiking for and what the average boost level is.

Also do you have an upgraded Electronic Boost Control Solenoid (EBCS)?

Also can you post a video of you revving the car in neutral so we can get a feel for what it sounds like. Preferably from the engine bay, Not inside the car. This will require two people.

 

[Scott Stokes]

20.1 is kinda high for a base stage 2 OTS map...

yeah thats not to bad, when i went to my stage 2 cobb map. i was at a steady 21psi with no spikes. And on a properly tuned turbo car you should really here no wastegate flutter. On a stock subaru turbo, any of the vf series. when you get wastegate flutter if you pull the turbo off and look real close to the flapper you will notice a small crack that has developed. It happens to a vf turbos. And if you are getting a flutter with a EWG then it is not tuned proper. The Cobb Forums can back me up on this. But this is only my two cents though.

 

[STimedic]

I had a bit of flutter with my DWG DP when I was still IWG, but no more boost creep!

 

[Casper86]

If you are hearing flutter at high RPM / WOT in higher gears it possibly could be compressor surge, although thats uncommon for a VF series.
I think 21 psi is pretty high for a off the shelf stage 2 map, have you looked up boost creep?,

 

[Bluedemon_II]

Recently went to COBB Stage 2 and I'm peaking at 20.1psi.

If in higher gears (where I can go mid-throttle for a good few seconds before getting through the gear) and I go mid throttle and boost to anywhere in the 10-20psi range I will hear a fluttering sound along with the air rushing sound of the turbo. What is this caused by and should I worry?

Do you have an Bov or a Bpv? If you have a stock Bpv it could be opening up due to some fluctuations in pressure inside the valve and it tends to sound like that. If you have a Bov you will know if its opening up.

Boost creep could cause some wastegate flutter.

 

[Scott Stokes]

http://www.turbosmartonline.com/index.php?id=624
Here is a cool link on wastegate flutter