hey ppls,

i am a bit baffled by this. Ever since i installed a silicon intake from afm to turbo inlet,and different dump pipe(from bell mouth to "flat plate" hks dump pipe) i sometimes hear what sounds like a fluttering noise on full boost with wide open throttle. i have noticed when this fluttering noise happens my boost gauge needle does flutter slightly as well.
seats of pants feeling tells me i am not loosing power when this happens. but i am more concerned about detonation etc (i didnt hear it pinging, but then again hard to hear in WOT situations with an exhaust

so far it has only happened on cold nights (leading me to suspect its boost spiking)

does my car need a retune? is boost spiking/surge detrimental to engine?

car has:
vf34 with no boost controller
stock tmic with silicon y-pipe
turbo back 3"
possumlink ecu
supporting mods (walbaro, pod)

thanks

compressor surge. not detrimental to the engine. increase wear and tear on the turbo in the long term.

port the wastegate.

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RS Liberty - Because WRX's are only good for parts...

Try here mate:

http://www.perth-wrx.com/vb/showthre...port+wastegate

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....slow and steady wins the race....fark that!!

Please explain this ???
Do you mean bell mouth with a splitter or a flat plate type dump pipe like the Subi factory one ??

If its like the factory one again you need a dump pipe like this one (2nd pic):HERE

J

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"You can turn your back on a person, but, never turn your back on a drug. Especially when it's waving a razor-sharp hunting knife in your eye." - Raoul Duke

Id say that HKS flat plate dump pipe is probably the cause. They suck. I dont see the logic behind why they designed a aftermarket dump exactly the same design as the stock dump.

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RS Liberty - Because WRX's are only good for parts...

Pretty sure i get the same thing (Same turbo as you) .. Only when i'm in 4th and plant it .. Get the fluttery sound during spool then it disappears. I am running a bell-mouth dump dump though, not a flat plate.

I think this was brought up before, I was under the impression it was the motor not being able to "ingest" the amount of air the turbo was supplying at that given point, may be able to be tuned out to some extent but the fix would be bigger cams, porting the heads etc.

My 2cents.

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[SIGPIC][/SIGPIC]
Should have bought an STI

yes mister 2 is correct

it basically does look like a stock dump, except the opening is for the exhaust wheel is 3". still has a flat plate covering the wastegate.
so changing dump pipe will eliminate it?

what is the boost level of a vf34 wastegate? i am getting readings anywhere from 17 - 20psi? is this very high? when i get compressor surge the gauge reads off the charts! (shitty lil speco 20 psi gauge)

I couldnt say for sure if it will eliminate it, but it would go a long way to solving your problem.

Go back to the bell mouth or a split dump design.

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RS Liberty - Because WRX's are only good for parts...