Bypassing the the bypass valve solenoid.

[MPFab]

"Compressor surge" and "compressor chuffing" are totally different things. Surge happens under high load conditions such as WOT with an incorrectly sized turbo. It will literally cause the car to buck or stumble as the turbo comes up on boost. This is very damaging to the turbo
Chuffing happens when letting off or reducing throttle position, after being in boost. How the throttle is released or modulated when backing off, can directly determine the amount of chuffing you get. The fact it doesn't happen under load, and that the duration is typically very brief, means that it is not damaging to the turbo.
Both of these can have very similar sounds while they are happening, but only one of them will result in the demise of the turbocharger being used.

 

[Larrymer]

Different names for the same thing. Reversed flow is coming back and hitting the compressor blades.

 

[Patgt500]

I actually started noticing flutter dump at lower boost levels. Maybe it has to do with me running the yellow spring in my forge bov.

 

[MPFab]

Different names for the same thing. Reversed flow is coming back and hitting the compressor blades.

Yes...and a bass and a shark are both fish, but only one of them will kill you.

This is actual "surge": True Compressor Surge - YouTube
That is what will kill a turbo.

 

[Preloader]

I actually started noticing flutter dump at lower boost levels. Maybe it has to do with me running the yellow spring in my forge bov.

That flutter is not a concern, as in it's not a sign of harm. Mine does it at cruise speeds as well. I actually like it. It helps my brain visualize what the BOV is doing in realtime.

 

[Patgt500]

I think that after the mod there is less vacuum to fully dump the extra pressure. In my case the stronger spring makes it harder to open with the reduced vacuum. I think if I swapped to the green spring it would go away

 

[Preloader]

I couldn't remember which spring was what color, but yeah, the softer spring is what I'm using and is plenty.

 

[Patgt500]

I'll do that when I have the chance, and am in need of some pain. :sadbanana: If we do have a vacuum canister under the IM it would make sense that taking it out of the loop would cause this. I don't remember personally if there is one there, didn't think to look at it when I had my IM out awhile ago.

 

[Preloader]

The vacuum canister is molded into the IM. I am considering ******* it off, but it does have a one-way passage to the intake, so I would need seal that shut. Maybe a little hot air welding will do the trick.

 

[Patgt500]

That would do it.

 

[Larrymer]

Yes...and a bass and a shark are both fish, but only one of them will kill you.

This is actual "surge": True Compressor Surge - YouTube
That is what will kill a turbo.

Granted the forces may not be as high in one situation vs. the other, I still say "chuffing" is a problem and side effect of your BPV not operating correctly and should be fixed one way or another.

Don't make your turbo cry, folks.

 

[MPFab]

Granted the forces may not be as high in one situation vs. the other, I still say "chuffing" is a problem and side effect of your BPV not operating correctly and should be fixed one way or another.

Don't make your turbo cry, folks.

The BPV works just as it should with this mod. The fact it actually seals without the solenoid means that in certain situations, sometimes you will get a chrip or two before the BPV opens. At least with this mod, the turbo is not spinning it's brains out anymore trying to maintain boost pressure with a leak. Over speed will kill a turbo quickly.
The "chuffing" only occurs when the throttle is closed slowly after accelerating in an upper gear like 5 or 6th and it's brief. An example would be passing a semi. You roll on the power, boost comes up and as you get past the semi, you slowly roll of the throttle. Because you are not getting into vacuum immediately, you might experience a couple chirps before the valve opens.
If you jam through the gears, it blows off like normal.
You should try it before passing judgment on it. It's easy enough to do and reverse if you don't like it. Then you can post your findings here.

 

[Patgt500]

I see the chirping or flutterdump or whatever on all gears at lower rpm's with lower boost. Pretty much unless I'm driving hard it does it.

 

[cndctrdj]

So I've put a couple hundred miles on this mod and I can say without a doubt. The car is smoother to drive. It does not seem to lunge at low Rpms or search for power either. I drive this car easy and it has been a pain in my butt to be smooth at low Rpms. A lot of clutch work and... Well anyway. With this simple mod it seems to not want to be stupid anymore and drives a lot more like a normal car. Now I just need to get rid of whatever is in this clutch assembly that makes the car so soft

 

[sx sonic]

So I've put a couple hundred miles on this mod and I can say without a doubt. The car is smoother to drive. It does not seem to lunge at low Rpms or search for power either. I drive this car easy and it has been a pain in my butt to be smooth at low Rpms. A lot of clutch work and... Well anyway. With this simple mod it seems to not want to be stupid anymore and drives a lot more like a normal car. Now I just need to get rid of whatever is in this clutch assembly that makes the car so soft

Good deal, how's your "turbo lag" now? You were having unimpressive throttle response or power compared to others correct?

And you mean that colossal 23lb double sprung dual mass flywheel and sprung clutch disc? . Sometimes I could swear GMs test drivers don't know how to operate a motor vehicle and also cruise around with a man-pon! Things like the clutch and BPV solenoid behavior are proof of this.

 

[MPFab]

I see the chirping or flutterdump or whatever on all gears at lower rpm's with lower boost. Pretty much unless I'm driving hard it does it.

You also have an aftermarket BOV with the stiff spring in it. Swap to the softer spring and that will go away.

 

[cndctrdj]

Good deal, how's your "turbo lag" now? You were having unimpressive throttle response or power compared to others correct?

And you mean that colossal 23lb double sprung dual mass flywheel and sprung clutch disc? . Sometimes I could swear GMs test drivers don't know how to operate a motor vehicle and also cruise around with a man-pon! Things like the clutch and BPV solenoid behavior are proof of this.

No lie, I think this was the turbo lag I was feeling. Haha and yes the clutch setup needs to go. If I find something streetable and inexpensive. I might make this car worth keeping for a long time

 

[Larrymer]

You should try it before passing judgment on it. It's easy enough to do and reverse if you don't like it. Then you can post your findings here.

I completely understand and know this is how turbo cars did it in the old days before everything was computer controlled. I just want others to make sure to fix their BPV/BOV if they're getting the sound like you're suggesting with a weaker spring, etc. Not trying to hate, btw.

I may give it a try later down the line but I don't drive the car too hard to begin with so I doubt I'd see much gain.

 

[ss2000slp]

It's worth doing just for the driveability aspect alone. Makes the manual trans waaaaaay smoother to drive. And all you have to do is reroute the factory line right to the manifold. Remove the black and green hose, and take the line from the bypass valve out of the wire loom bracket, and it goes right onto the intake manifold with the little hose clamp and all. IMO best 10 minutes you can spend on your car.

 

[SONIC1.4]

Sooo this new sound I'm hearing is bad?? I thought MPFab said its good?