so basically my question is, IS THIS COMPRESSOR SURGE UNDER WOT?

http://youtu.be/Z1J7era9Opc

this is not my car for starters. the reason i ask is cuz for one the title says running through the gears to hear compressor surge, but in the description it says running through the gears to hear what sounds like compressor surge. another reason i ask of course is because yesterday my car made this sound during a 4th gear pull and it scared the **** out of me. i thought the blades of the turbo were about to come through the cabin of my evo.

it didnt sound 100% like this as once i heard this sound i immediately glanced at my boost gauge and it was bouncing from 28ish to 24ish psi and its suppose to be at 25psi falling to 21. it also differs from this video as when i heard the sound i slightly lifted throttle and the sound changed to what sounded like my bov going off again and again really fast and then i let out, all in the fraction of a second.

so my question is, is this surge? if it is, whats causing it now when nothing has changed. im going to assume its because the turbo is close to being maxed out and the addition of a little colder weather causing a rise in boost, but i thought there were quite a few people pushing the 8 turbo in the 30+ psi range with no ill effects? if needed ill post more details on the car including mods. im justt assuming its because of the weather since this past summer it wasnt doing this, and now when it did this it felt like the car had no power at all.

 

what BOV are you using?

 

This sounds more like flutter. BOV might be opening prematurely. Could be because of the cold, freezing everything from vacuum lines to internals. I think you would have to lower boost back down.

Surge wouldn't be under WOT. Surge is when the BOV isn't opening and the air has nowhere else to go except back out through the turbine and out the intake.

 

Compressor surge wouldn't last that long, has to be something with the BOV

 

Sounds to me like BOV flutter.
My car will do that in 5th gear if I am at a low RPM. Once, the boost builds up, the BOV fully shuts. The way I've gotten around it is just by down shifting from 5th to 4th.

In your case, it seems the BOV is not working correctly. It's essentially a big boost leak. What BOV is it? Have you done a boost leak test?



-Bink

 

what bov is this

 

There are other types of surge.

http://www.youtube.com/watch?v=nCj6Spwl1CU

 

Yep that is true comp surge

 

comp surge will last as long as the turbo is in a surge condition

 

Hmm, it does kind of sound like compressor surge.. I wonder if the vacuum line to the BOV is T'd to something else. I had a greddy type s bov a long time ago that did a similar thing when the rubber diaphragm inside developed a tear.

Although.. Maybe the exhaust pressure is pushing the wastegate open before the boost controller is letting boost pressure get to the diaphram of the WG. So the valve of the wastegate is just kind bouncing from the pressure of the spring.

 

The third run in this video sounds alot like what's going on except for the chirping whistle type sound. It basically sounds like a thick piece of paper flapping in the wind or something. I backed some of the tension off of the wga and going to do a few pulls later today and adjust the boost to see if it fixes the issue. I've also been reading surge happens more in the higher gears from lower rpm just like whta I experienced first and second gear the boost gauge slams 25 and holds without this noise. Not sure about third but in 4th is when it happened. Im also going to do a leak test and check my plugs later as I I have heard the gaps can open up after a few heat cycles and I recently changed them and gapped them to around .022

 

So are you asking us what it is or telling us? 6 people have referred to the BOV and asked what kind you're using. Do you know? What kind of turbo are you running?

 

The first time I watched the video was on my phone. Sounded as if the surge lasted throughout the entire powerband, which after rewatching it, I realized that was not the case.

 

Hey guys, sorry if I'm bringing back a thread. My situation is this: Only when the car is cold when I first take off the car jerks a bit when I give it normal gas. Like only 1st and 2nd gear. Car is stock.

 

sounds like flutter, just like bink said.. my car does it in 5th and sometimes 4th.