Turbo flutter noises

[michaelf80]

Hey everyone, I’ve been having crazy oscillations in the part throttle range followed by this weird air whooshing noises. Attached is a video and if you listen closely right after the gear shift, you can hear the whooshing air. This happens after any gear shift under mild load, but goes away when WOT. The system was leak checked and passed. Any thoughts to what can be causing this? Sounds like turbo flutter or some sort of compressor surge. Issue is present in any engine mode she stock map. Sounds like air is rapidly passing over something.
Turbos are PS2+

[michaelf80]

Video won’t upload.

[michaelf80]

This log shows the oscillations caused by this. I am able to reproduce the issue every time and hold it throughout the gear.

http://www.bootmod3.net/log?id=5cf559d2ae729b2e438ff103

[mdma-zn]

WGDC is consistently maxxed out
mechanical issue with turbo or wastegate?

[Machtavian]

Sounds like turbo surge to me. This is a common issue when you put big turbos on a small displacement engine. The engine can't use all the air that's being moved by a big compressor wheel,usually at lower rpms, causing the air to backup in the turbo. There are a few options to fix this issue. Either increase the VE of the engine, ie port work and cams, or buy a better balanced turbo like the Kratos turbo kit.

[michaelf80]

Originally Posted by Machtavian

Sounds like turbo surge to me. This is a common issue when you put big turbos on a small displacement engine. The engine can't use all the air that's being moved by a big compressor wheel,usually at lower rpms, causing the air to backup in the turbo. There are a few options to fix this issue. Either increase the VE of the engine, ie port work and cams, or buy a better balanced turbo like the Kratos turbo kit.

Here’s a current log that I went WOT. The head is ported and it has upgraded valve springs and built motor

http://www.bootmod3.net/log?id=5d457d04ae729b7139757d08

[michaelf80]

Originally Posted by mdma-zn

WGDC is consistently maxxed out
mechanical issue with turbo or wastegate?

http://www.bootmod3.net/log?id=5d457d04ae729b7139757d08

[Machtavian]

If the VE is already increased and the turbo is still surging, your only option is to get a better matched turbo. The problem with the pure + turbos is that the compressor is to big for the stock sized manifold and exhaust housing causing the air to back up in the compressor. The kratos turbo is your best option. They increased the a/r of the turbine housing and casted a larger manifold to allow the extra air to move with out backing up in the manifold and turbine.

[michaelf80]

Originally Posted by Machtavian

If the VE is already increased and the turbo is still surging, your only option is to get a better matched turbo. The problem with the pure + turbos is that the compressor is to big for the stock sized manifold and exhaust housing causing the air to back up in the compressor. The kratos turbo is your best option. They increased the a/r of the turbine housing and casted a larger manifold to allow the extra air to move with out backing up in the manifold and turbine.

That can’t be my issue since I’m the only one having this surging issue. It has to be something else, not the size of the manifold.

[AutoTalent]

We had a car come in from another shop that was here recently experiencing similar, who tuned the car?

[michaelf80]

Originally Posted by AutoTalent

We had a car come in from another shop that was here recently experiencing similar, who tuned the car?

F80 Paul, and he said he hasn’t seen anything like this before.

[Machtavian]

Originally Posted by michaelf80

That can't be my issue since I'm the only one having this surging issue. It has to be something else, not the size of the manifold.

Not everyone posts about sensitive things like this that can hurt someone's bottom line. I have been wondering for a while if they're f80's out there experiencing surging issues. It's something that is inevitable when you throw a large turbo wheel on a small stock turbo housing. I have seen it tuned out before by keeping the wastegate open longer not allowing the turbo to build boost low in the rpm range, where most surging occurs, but it's not ideal. It causes a lot of lag which is no fun to drive. It's hard to stay in front of the turbo surge line with a small displacement motor. You have to remember that only 1.5 litters are feeding each turbo.

[michaelf80]

Originally Posted by Machtavian

Not everyone posts about sensitive things like this that can hurt someone's bottom line. I have been wondering for a while if their are people out there experiencing surging issues. It's something that is inevitable when you throw a large turbo wheel on a small stock turbo housing. I have seen it tuned out before by keeping the wastegate open longer not allowing the turbo to build boost low in the rpm range, where most surging occurs, but it's not ideal. It causes a lot of lag which is no fun to drive. It's hard to stay in front of the turbo surge line with a small displacement motor. You have to remember that only 1.5 litters are feeding each turbo.

There are cars with the same setup as me and videos of the same setup and nobody has the same issue/ sound as me. It has to be a mechanical issue

[behindthen0thing]

Originally Posted by michaelf80

There are cars with the same setup as me and videos of the same setup and nobody has the same issue/ sound as me. It has to be a mechanical issue

Ever resolve this?

[andrei.m4]

Check wastegate

[E92inSG]

Omg. I’m having the same exact issues!

https://f80.bimmerpost.com/forums/sh....php?t=1706762

Maxed out WGDC and boost oscillations and audible fluttering, at lower boost levels.

Also running ps2+ and f80paul tuned

[M3ZCPNYC]

I have the same issue FBO with pure stage 2+ I recorded a video but can't upload. It's only at low RPMs while I build boost. I just think it's compressor surge. May have to just build my engine now.....

[E92inSG]

OP has sold his stage 2+ turbos. probably was unable to ever resolve his issue
https://f80.bimmerpost.com/forums/sh....php?t=1643472

[E92inSG]

Originally Posted by M3ZCPNYC

I have the same issue FBO with pure stage 2+ I recorded a video but can't upload. It's only at low RPMs while I build boost. I just think it's compressor surge. May have to just build my engine now.....

do you have oscillations in your bm3 boost logs?

[michaelf80]

Originally Posted by E92inSG

do you have oscillations in your bm3 boost logs?

Decided to go Kratos. Hopefully all goes well, you should be fine though. The oscillations did not make for less power.

[papasmurf_m3]

Originally Posted by michaelf80

Decided to go Kratos. Hopefully all goes well, you should be fine though. The oscillations did not make for less power.

How much power were you making on pS2+ ? GL and keep us posted with your results!

[M3ZCPNYC]

I don't have BM3 I have JB4 and I haven't logged