compressor stall, it's happening. Now with a vid link...

[UrSobsessed]

How, how do get it to stop? My HTA3073 lets out some pretty serious chirps before the BOV(Tial Q) opens up between shifts. Also, if the boost dropped from high to low without pushing in the clutch it chirps as well. Maybe this is somewhat normal, but it sure as hell doesn't sound normal. I know that the BOV is supposed to release pressure under a vacuum signal, but there's about a second of chirping before the whoosh. Also, when just lowering the boost, the BOV doesn't really get a vacuum signal to release the pressure, so is the wastegate(stock) supposed to open here and let the turbo slow down?

Maybe this is normal? I've got the right spring in the BOV and a 1.9bar spring in the WG...

Thanks for any input guys!

[Hank]

What is the deal here? That turbo isn't big enough to be surging with that compressor. I am starting to suspect the BOV?

[EDIGREG]

Yeah, classic behavior when the BOV spring is too stiff. I know you say its correct but I'd try a softer one.

[loxxrider]

Agreed ^^^

[UrSobsessed]

I agree with the too stiff of a spring theory but I've tried the next softer spring and it still does it. That spring also has a bit of initial creep until enough pressure builds in the manifold to hold the valve closed.

Could the altitude be playing into this a bit. I might be reaching here but perhaps the turbo is spinning more here to achieve the target causing more back pressure than normal? Thing is, I'm running the same boost pressure as was on my 1+ SW/k24 and never heard this.

[Hank]

You need some vids or something.

Hank

[EDIGREG]

Which springs are you talking about?

I'm using the white -8psi spring in my Tial Q if I remember correctly. Either that or the black one, I forget. I idle around 13-14in/hg when warmed up.

[UrSobsessed]

I'll work on the vids Hank.

I'm running the -8 spring also. The -6 behaves the same except with some valve creep at low boost. My vacuum when warmed up is the same as yours Ed.

[UrSobsessed]

The mic on my phone was just able to pick up the sound of the pigeon, and the whooshing of the BOV. I moved up and down on the throttle a bit under boost to get the thing to chirp a bit more also. It's kinda faint, but hopefully you can hear it...
http://www.youtube.com/watch?v=ecRXDOYo ... e=youtu.be

How do I embed vids? I'm sure it's easy, but as usual I'm missing something...

[EDIGREG]

Dace - I did some testing and my car does the same thing over 20psi... hard to hear with the exhaust cutout. I think the BOV just can't vent that much air volume quickly enough. A larger BOV or a second one may be necessary to completely prevent it.

[EDIGREG]

How do I embed vids? I'm sure it's easy, but as usual I'm missing something...

Use only the youtube.com/watch?v=xxxxxx part of the link. Remove everything from the first ampersand on.

[UrSobsessed]

Ah. Thanks.

Could this damage a turbo eventually? The seals specifically...

[ur20v]

Yes, surge will damage/destroy a turbo.

I don't think the BOV undersized. Even at 20psi, it should be more than adequate.

External wastegates can and do "flutter", and this can be mistaken for compressor surge.

For compressor surge, I would first check the vac plumbing to your BOV and test it with a My-t-vac to make sure the signal line isn't collapsing under vac. Make sure the BOV has its own independent vac line to the manifold. Next check your manifold plumbing for vac leaks. Is the needle of your boost gauge bouncing or varying at steady idle?

The 1.9 bar WG spring is too much in my opinion. Works great on a chipped K26 with stock supporting hardware, but you're in a different ballpark now. You're probably running too much onset for your motor/turbo. Believe it or not, a little bit of wastegate creep isn't always a bad thing, and can actually help you push the performance envelope while staying out of compressor surge. I would swap back the stock 1.4 bar spring and get a good MBC to fine tune it with. If you can't get it quite perfect here, then you can further fine tune it with your BOV springs and shims.

[Hank]

That kind of surge will not damage turbos, especially a ball bearing assembly. Thrust washers get eaten up by turbos surging on acceleration under load, but the off load chirp is somewhat normal.

Won't do anything on the seal front. The only damage it can do it on the bearings, and ball bearings have enough thrust control, that I don't see the chirp you are seeing donig anyting

[UrSobsessed]

Ok then. That's good to know. I'm still trying to get to the bottom of my oil consumption issue and if the seals on the snail could've been jacked by the pigeon.

[UrSobsessed]

As far as the vac line is concerned, I'm using thick walled silicone line that holds up well under vac. No vac leaks exist.

[JustinB_20vt]

FWIW my gtx3071 with at Tial Q does it too. switched to a lighter spring (plain i believe) and it noticeably decreased but didn't fully go away

[EDIGREG]

Yeah, like Hank said it isn't going to damage the turbo. Although mine does not seem as severe as yours, and it doesn't happen on WOT shifts (even at 30+psi)...only when boosting then quickly snapping throttle position to 0%. Probably because you're right back on the throttle when shifting so the throttle is only closed for a few tenths of a second.

[UrSobsessed]

Hmm. Ok then. I might have to pull this thing again to see if the seals are leaking. Sux. If not, I don't know what to do next...

[FRCFD5]

With a softer spring you might see less of this, but then you might have the valve open during idling...

[Rocket SLC]

This sounds more like the WG is fluttering. What size vac line is going to the BOV? Its is a direct line from the manifold?

[UrSobsessed]

4mm ID line, directly to the stock port.