[Rupes]

I know this thread doesn't deliver without a video, but I'm wondering if anyone else's 328i (naturally aspirated) makes a spooling down type sound when shifting slowly at a high RPM. What the hell is that? For example, take the car to 7k RPM, hit the clutch, wait a second to shift and I hear vuuuu. It's not the engine sound though. Flywheel maybe? I just want to know others have it too I guess.

[Eagle1oh7]

Intake sound.

[Rupes]

Originally Posted by Eagle1oh7

Intake sound.

Your right, thanks. /thread

[Light_Em_Up]

My 2009 128 has made the sound as you describe since new and I have always wondered what it is. I have changed my intake and my manifold to a 3 stage without any perceptible change in this sound so I'm questioning whether it is intake. It sounds to me like a 20k+ rpm gear set or turbine winding down. What else could it be?

[Eagle1oh7]

Originally Posted by Light_Em_Up

My 2009 128 has made the sound as you describe since new and I have always wondered what it is. I have changed my intake and my manifold to a 3 stage without any perceptible change in this sound so I'm questioning whether it is intake. It sounds to me like a 20k+ rpm gear set or turbine winding down. What else could it be?

All I know is that it sounds lovely.

[BoogeyMan'sBMW]

I think it is the twin turbos spooling

[Rupes]

Originally Posted by BoogeyMan'sBMW

I think it is the twin turbos spooling

The engine is naturally aspirated, I think it must be the intake.

[BoogeyMan'sBMW]

Originally Posted by Rupes

The engine is naturally aspirated, I think it must be the intake.

Haha , i know brotha man i was just kidding. It is the intake, and if you and I are thinking about the same sound its when you get the car up to high RPMs and dont shift, just wait for it to come back down slowly, right?

[Rupes]

Originally Posted by BoogeyMan'sBMW

Haha , i know brotha man i was just kidding. It is the intake, and if you and I are thinking about the same sound its when you get the car up to high RPMs and dont shift, just wait for it to come back down slowly, right?

yea, sort of. But the clutch is engaged so the engine is dropping quickly but the "spooling sound" lingers.

[SDemetris]

I think it might be the alternator is just loud. I noticed it on my car.. it sounds like sound thing with square cut gears spinning very fast. the only thing i can think of is the alternator since our belts dont drive much else

[Surly73]

Originally Posted by Rupes

yea, sort of. But the clutch is engaged so the engine is dropping quickly but the "spooling sound" lingers.

Alternator overrun, probably. Recall these cars have a one way bearing (like a bicycle) on the alternator.

[WOT Bimmer]

I notice this same sound on my '07 AT (steptronic). If I am in M1 and bring the RPMs up to the 5-6k+ range, it make a spooling/ziiiiiiinnnnng sound, especially if you bring it up to 5-6k+ and then let off the gas.

[Dylanize]

It's the vanos system doing its thing. Not the intake.

[Rupes]

Originally Posted by Surly73

Alternator overrun, probably. Recall these cars have a one way bearing (like a bicycle) on the alternator.

Is alternator overrun bad? I now have three very different answers - I preferred the intake answer the best, heh. Maybe that means it's time to post a clip of the sound.

[Surly73]

Originally Posted by Rupes

Is alternator overrun bad? I now have three very different answers - I preferred the intake answer the best, heh. Maybe that means it's time to post a clip of the sound.

That just means that the alternator's momentum has it spinning faster than the engine when the engine slows quickly. The one-way bearing in the pulley is there for a reason and that is to allow that to happen. This is the first car I've had where the alternator pulley wasn't just a pulley.

I'm not sure exactly what people thought was "spinning" or "spooling down" in a tube carrying air just because you revved the engine up, but....

Now, that being said, as a 6MT driver I actually find that the engine doesn't have ENOUGH momentum. Sure you can do these cool sounding throttle blips that sound really responsive but it can be a PITA to drive when the revs drop like a stone every gear change, especially with the 328 being made "extra quiet" for whatever reason.

[cyclicoyster]

I notice a gentle whistling sound on my car, but at very low revs. My car is a 328i, and DD, so on a daily basis it doesn't get driven hard. I have an AT, and it shifts at around 2500 rpms. The whistling sound starts at take off and quiets down at around 50mph. Have no idea what it is, but the car is running perfectly fine. Add to that, I love the way that sounds. I don't mind it at all. Sometimes I turn the stereo off just to hear that

[v1valarob]

Originally Posted by cyclicoyster

I notice a gentle whistling sound on my car, but at very low revs. My car is a 328i, and DD, so on a daily basis it doesn't get driven hard. I have an AT, and it shifts at around 2500 rpms. The whistling sound starts at take off and quiets down at around 50mph. Have no idea what it is, but the car is running perfectly fine. Add to that, I love the way that sounds. I don't mind it at all. Sometimes I turn the stereo off just to hear that

I know this is an old thread, but Im having the same issue.

The car has had this sound ever since I purchased it over 2 years ago. In that time Ive replaced the tension belt, pulley, alternator pulley thing. I assume it has to do with the intake system as it sounds like air and the sound directly correlates with the position of my foot on the pedal.

It honestly sounds like a leaf or something is inside the intake manifold. Ive pulled out the intake filter box, cleaned it up, replaced the filter. Next step I guess would be to pull out the entire intake system and clean it up.

I figure Id see if in the past 2 years anyone else has actually figured out what this was.

[Three_thirty_I]

If it's the noise that I think is being discussed, then my bet is that it is the variable oil pump. The spooling down noise seems to be not directly related (not at the same rate) as the engine speed returning to idle. You hear it whenever these engines are revved.

Check these vids, pretty sure the whining/spooling sound is what you are talking about:

Threads where these vids were from: Whining noise from N52B25 and Remus Powersound + AA Headers

[bimmerquick43321]

Every time I see your vid, damn I like how it sounds, that's exactly what I want for my car sound wise..

[refugeeofwar]

May or may not be an issue in your case, but I have the N52 without a 3-stage intake or anything and my intake whistles and sounds like a small turbo starting at 4500k and up. It's kinda neat.

[v1valarob]

Originally Posted by Three_thirty_I

If it's the noise that I think is being discussed, then my bet is that it is the variable oil pump. The spooling down noise seems to be not directly related (not at the same rate) as the engine speed returning to idle. You hear it whenever these engines are revved.

Check these vids, pretty sure the whining/spooling sound is what you are talking about:

[/URL]

Thats not the sound.

I think my main issue is that my girlfriends vehicle is the exact same as mine, a 2007 328i, but it does not make the sound. If I hadnt driven another vehicle like mine I probably wouldnt care, because I wouldnt know any better.

[Taskmaster]

It's Vtec.