Surge vs intake flutter

[arnoldS3]

Hi guys,

Can someone clear this up for me once and for all, how would you diagnose if your car is surging excessively?

Some people say it's that fluttering sound that comes from a aftermarket intake, some say it's bacpressure on turbo inlet, I have read the complicated google techie explanation but I want a more simpler explanation

Thanks ,

[Jetta2]

Compressor surging (extreme case):
http://www.youtube.com/watch?v=nCj6Spwl1CU

I have read that the fluttering noise on the intake is perfectly normal on those cars though. It is due to the intake design and the OEM dumpvalves dumping air into the intake and not to atmosphere. I have heard tons of Mk5/6 GTI's, S3's etc sound like that.

Zubair or Panic can give a more scientific explanation.

[arnoldS3]

I also never really bothered with the flutter on my car coz it would be till like 4000rpm then disappear.
Some random guy i chatted with from a custom tuning house said that that flutter could mean there
is a surge on the turbo which could mean that the map is not optimally setup for the intake or some
thing like that, will check that video out when i get some MBs,lol

thanks for reply though, ive heard it on a few cars aswell, so what i still wanna know is if the flutter is
just as you an dumpvalve releasing into the intake, what would a surge sound or feel like

[1.8iblackie]

Surge has got very little to nothing to do with the mapping of the car.
Surge happens when the compressor is producing more airflow that the engine can ingest.
This causes the compressor wheel to rapidly slow down and accelerate again.

This is extremely damaging to a turbo. Imagine the stress on the turbo shaft it the turbine blade is trying to speed it up and the compressor wheel is trying to slow it down. Surge mostly occurs when the turbo is wrong for the application or the DV doesnt responds well enough to stop the turbo from a dead head condition when U rapidly close the throttle.

[panic-mechanic]

Unfortunately i have no idea which car you are talking about but often what is percieved as flutter is the boost controller doing it's job if we are speaking of an oem installed system.

[Killerwatt]

Its been said already but il explain what surge is again. basically its when you run the turbo at too much boost at too little flow. The boost ends up pushing itself backwards through the compresor and thats how **** breaks.
We actually did surge testing on some of our 2 megawatt compressors recently, sounded like a tsunami was aproaching. not sure what your turbo sounds like though.

[Zubair]

Compressor surging (extreme case):
http://www.youtube.com/watch?v=nCj6Spwl1CU

I have read that the fluttering noise on the intake is perfectly normal on those cars though. It is due to the intake design and the OEM dumpvalves dumping air into the intake and not to atmosphere. I have heard tons of Mk5/6 GTI's, S3's etc sound like that.

Zubair or Panic can give a more scientific explanation.

Explained in bold. Combination of recirculating dv's and also the aftermarket intake pipe design. Nothing to stress about. Surge will be identified by interrupted power delivery almost like a miss or jerk even when accelerating gently.

[ruan9n]

I once heard a mk6 gti k04 on kar's dyno that was surging heavily.... whaaap whaaap whaaaap whaaap this continuous kak sound like the car was struggling to move.

[RoadHaWg]

I was also worried about it when I got my Cupra, but it's never missed a beat and gets driven hard any time I can.

Got a video of the sound somewhere.

[RoadHaWg]

You can hear it start a bit here.