[sdogatvman]

Hey I am going to be running a single turbo setup on an e92 and was wondering why no one has ever gotten the turbo surge sound. If I used a turbo compatible with surge pressures, would it be possible to run no bov and get that sound without causing issues?
Thanks!

[lowrydr310]

Originally Posted by sdogatvman

Hey I am going to be running a single turbo setup on an e92 and was wondering why no one has ever gotten the turbo surge sound. If I used a turbo compatible with surge pressures, would it be possible to run no bov and get that sound without causing issues?
Thanks!

What 'turbo surge sound' are you referring to? I believe the sound you're thinking of is actually the sound of a proper blowoff. I'm not familiar with any turbochargers that are compatible with surge pressures, I always thought that the surge pressure could cause a compressor stall and easily destroy the turbocharger, which is why a blowoff valve is a critical component of the system.

Most cars are designed to muffle that sound, with a carefully designed blowoff valve and intake tract to minimize the sound. I'm not familiar with N54/N55 blowoff valves, either stock or aftermarket, but back in my old turbo Mitsubishi 4G63 days there were many aftermarket blowoff valves that made that sound, which was even more pronounced with certain brands of intakes. I rented a Ford F150 3.5 Ecoboost V6 turbo and that had an audible blowoff sound, even more pronounced in tunnels!

Some of the blowoff valve options vented externally, meaning they relieved the surge pressure outside of the intake air path (but if the engine management computer wasn't programmed to compensate for this, you'd get a momentary rich condition, discharging already metered intake air and the computer would delivery fuel for the amount of air that was measured). This is just general stuff I recall from my old turbo days. I'm not familiar with the N54/N55 turbo systems so I can't help you there.

[ckanderson]

Originally Posted by lowrydr310

What 'turbo surge sound' are you referring to? I believe the sound you're thinking of is actually the sound of a proper blowoff. I'm not familiar with any turbochargers that are compatible with surge pressures, I always thought that the surge pressure could cause a compressor stall and easily destroy the turbocharger, which is why a blowoff valve is a critical component of the system.

Tell that to the GN guys lmao

[upshift_downshift]

Originally Posted by sdogatvman

Hey I am going to be running a single turbo setup on an e92 and was wondering why no one has ever gotten the turbo surge sound. If I used a turbo compatible with surge pressures, would it be possible to run no bov and get that sound without causing issues?
Thanks!

Compressor surge is not a good thing, the sound means you are risking damage. It's caused by the blades "chopping" through the air instead of moving it. This causes high-frequency pressure fluctuations, which induces fatigue. Fatigue means the failure will not happen right away, but it will eventually happen over time. And when it does, it will send shards through your intake system, destroying your intercooler and likely your engine.

Turbos are not designed to sustain surge, that would require stronger wheels, which slows spool down from the added mass. Just make sure you are using a turbo that is well-matched to your engine (overlay the pressure ratio vs mass flow for the engine on the compressor map), and use a blow-off valve like a properly engineered setup.

EDIT: Borg Warner's MatchBot is very useful for turbo matching:
http://www.turbos.bwauto.com/aftermarket/matchbot.aspx

[sdogatvman]

Originally Posted by ckanderson

Tell that to the GN guys lmao

Please explain...

[ckanderson]

Originally Posted by sdogatvman

Please explain...

Buick Grand Nationals never had them and didn't have any issues

[sdogatvman]

Originally Posted by upshift_downshift

Compressor surge is not a good thing, the sound means you are risking damage. It's caused by the blades "chopping" through the air instead of moving it. This causes high-frequency pressure fluctuations, which induces fatigue. Fatigue means the failure will not happen right away, but it will eventually happen over time. And when it does, it will send shards through your intake system, destroying your intercooler and likely your engine.

Turbos are not designed to sustain surge, that would require stronger wheels, which slows spool down from the added mass. Just make sure you are using a turbo that is well-matched to your engine (overlay the pressure ratio vs mass flow for the engine on the compressor map), and use a blow-off valve like a properly engineered setup.

EDIT: Borg Warner's MatchBot is very useful for turbo matching:
http://www.turbos.bwauto.com/aftermarket/matchbot.aspx

Thanks for the Information. I also hear a lot of guys running without a BOV on different vehicles such as the r34 or MKIV. Why should they be able to get compressor surge without constantly blowing turbos, vs a single turbo n54 set up.

[sdogatvman]

Originally Posted by lowrydr310

What 'turbo surge sound' are you referring to? I believe the sound you're thinking of is actually the sound of a proper blowoff. I'm not familiar with any turbochargers that are compatible with surge pressures, I always thought that the surge pressure could cause a compressor stall and easily destroy the turbocharger, which is why a blowoff valve is a critical component of the system.

Most cars are designed to muffle that sound, with a carefully designed blowoff valve and intake tract to minimize the sound. I'm not familiar with N54/N55 blowoff valves, either stock or aftermarket, but back in my old turbo Mitsubishi 4G63 days there were many aftermarket blowoff valves that made that sound, which was even more pronounced with certain brands of intakes. I rented a Ford F150 3.5 Ecoboost V6 turbo and that had an audible blowoff sound, even more pronounced in tunnels!

Some of the blowoff valve options vented externally, meaning they relieved the surge pressure outside of the intake air path (but if the engine management computer wasn't programmed to compensate for this, you'd get a momentary rich condition, discharging already metered intake air and the computer would delivery fuel for the amount of air that was measured). This is just general stuff I recall from my old turbo days. I'm not familiar with the N54/N55 turbo systems so I can't help you there.

Thanks for the input, but I'm specifically referring to compressor surge when the air gets pushed back out through the turbo in the reverse direction.