So I have to admit this guys, I got my charge pipe installed, Intake tube, airbox mod, downpipe and exhaust installed. My surge when shifting at low boost is gone. I don't hear it. Sure my exhaust is louder, but I honestly can't hear it at all. I rolled down my window and all I get is a bov sound at lower dB, it's kind of cool.

The other thing I've noticed is shifting at 3000 rpms, my RPM's down decline as fast. So it stays up longer. It's also odd.

The sound is more like a release of shoosh noise with a couple of breaks (so like shoosh shoosh shoosh) sound at low boost and at high boost it's a psssst noise.

Maybe releasing my back pressure from the turbo actually helped.

 

Well, I also see often things written on this forum regarding Dejon products being excellent, so probably you made a good choice right there.

 

Well the thing is I had tuned my car and put the spring on and I would surge every time I shifted under 5 psi. I thought this was bad and now I don't hear it any more. Is it because my car is creating more efficient boost now and the back pressure is gone?

 

I wish i can answer that lol

 

Just did the same thing and it fixed my problems...

 

Great, so it still surges.

 

I guess but the sound is way Different than it originally was. Now instead of a wowowow or rowrowrow type noise it's like a quieter deeper pssst but more than one and less than 3 breaks.

 

I think it's still doing it. The difference is since you changed parts it changed the sound of it. Also, it's possible that you created more volume for the pressure to sit in (with different charge pipes), so not quite as much of it is making it's way back to the turbo.

I think you've changed the sound, not the problem.

NO surge is ideal, but low boost surge probably isn't going to shorten the life TOO much. I've done some research on the issue.

 

what do u guys mean when surge?

 

I see this makes sense to me. So technically I'm still surging but not as bad correct? More volume is causing the spring to give a little more but not enough to fix the problem.

If that's what you're implying than I understand.

 

I was getting this noise but only when I shifted below I'd say 5 psi. This I came to learn is surge with the spring. I have read that surging isn't too bad at low boost becaus the turbo is about to stop spinning anyway or something like that. And the surge only stops the turbo from spinning, maybe I'm slaughtering what Dave said. Can't remember what Dave said but what I got from it is it's not too bad for the car. Then I got a bunch of nay Sayers saying the surge and spring causes all sorts of problems.

YouTube - Cobalt

 

Yup, you are officially surging like mad. Enjoy that spring

 

No problems that i notice

 

Maybe it's my car in particular, I'll put in the factory spring and see what happens here in a bit.

 

Forge motorsport bpv doesnt do that.

 

I try to tell you have too much back pressure. My car exactly sounded like that in the video. I removed my stock dp and put the catless back on. BAM! Surge and Flutter Gone at Cold Start. I'm running the Forge BPV with the green spring pushing 24-26psi with 38-40lbs of airflow in the turbo.

 

That has nothing to do with it... A BOV or BPV spring is set specifically for an amount of Vacuum. This is the wrong spring rate, /thread.

If you can't tell by that sound that that's bad, that's a different problem. Learn what backspinning a turbo sounds like and return to the thread..

 

BYT to the rescue!!!!!

 

Goodbye BYT

 

That video isn't my car just an FYI, the noise it's making however is what my car did ONLY during shifts at low boost. It was so short though, it lasted only a second or two. Now that I got my downpipe, it's a lot less noticable (maybe due to exhaust) and it has a completely different tone. It's more airy than barky now. If that makes sense. It doesn't matter anyway, as soon as my forge motorsports bpv comes in, I won't have to worry about it. FWIU (From what i understand, is that even a real Internet lingo thingy) Forge's BPV doesn't surge or need to be tuned for

Just a FYI, I could still be surging, I'm just mentioning what I've noticed, I have no science or past experiences to vote either way.

 

Oh, then I shall not

BASH



or TORCH




BYT then.

Now that you mention that.

 

So here's a question for people.

I had the stock spring. Maybe it started wearing out.. I don't know. (almost at 70K miles!!) I could hear that bitch constantly letting off boost. Many times just a steady little whistle. Oh and yes I am 100% sure, no doubt whatsoever, it was NOT the turbo and in fact the BPV.

I changed to the Dejon spring. Well the problem I just mentioned is of course gone. The car drives SO much better than it did. I do have LOW boost surge ONLY during shifts, just like the OP. I also have intake and DP.

So here's my question... sort of. I don't want to go through the trouble of replacing the damn BPV, I just want a spring that works. The stock spring clearly wasn't. The Dejon is clearly too stiff.
I think the stock spring is 8-9 lbs and the Dejon 12-13 lbs if I remember correctly.

So is there a place that I can buy a spring that is maybe... like.. 10 lbs? Maybe one for a different BPV/BOV that will work?

 

Impressive, you can work a lighter lol.. Still doesn't change the fact you don't understand how it works.

 

Yeah that seems like it can't be solved. Have you tried replacing the bpv with a new stock spring. The problem seemed to have developed over the years. So if you get another stock spring it could take you to 120k miles

 

It's not letting off boost when you're tooling around at low rpm... It' open because YOU'RE IN VACUUM.