Addictive Blowoff Sound On My F21

bimmerblanco · 02-25-2014, 12:50 PM

Hi, I just wanted to write about my 2014 F21 118i with 2,600 kms and ask something about the blowoff sound.
At first when I bought it I was no so sensitive to the sound that the turbo does when you pull up your foot from the throttle, but weeks passes and I am more conscious now about that great sound.
What I noticed is that you don't have to go very fast or have the engine at high revs to have the whistle.

My first question, it´s totally normal?

I´ve drove some turbo cars like Audis, VW, and Dodge, and that whistle is not so gorgeous and not so present as the one in BMW. It feels like if you have it on your butt.

Can someone detail more about this? How does it works, when, and where is located?

Thanks!

JordW · 02-25-2014, 02:07 PM

It sounds it's best in multi storey car parks!!

It is normal - it's not a dump valve just a bypass valve after the turbo not sure on the exact differences. Both let off excess pressure which is what you hear.

ovekvam · 02-25-2014, 02:29 PM

When you go off the throttle, the Valvetronic will close the inlet valves. That will in turn take away the energy in the exhaust, which is what powers the turbo. Since the inlet valves are closed, the turbo will build excess pressure in the inlet manifold. Combined with no power from the exhaust, the turbo will stall. To avoid this, the excess pressure is simply let out by an air valve. You can see it in front of the engine, right next to the turbo.

In our 116i, I can not hear it while driving, but spectators report that the car is making dump sounds when I release the throttle.

02-25-2014, 12:50 PM	#1
bimmerblanco New Member 3 Rep 16 Posts Drives: BMW F21 2014 Join Date: Nov 2013 Location: MEXICO iTrader: (0)	Addictive Blowoff Sound On My F21 Hi, I just wanted to write about my 2014 F21 118i with 2,600 kms and ask something about the blowoff sound. At first when I bought it I was no so sensitive to the sound that the turbo does when you pull up your foot from the throttle, but weeks passes and I am more conscious now about that great sound. What I noticed is that you don't have to go very fast or have the engine at high revs to have the whistle. My first question, it´s totally normal? I´ve drove some turbo cars like Audis, VW, and Dodge, and that whistle is not so gorgeous and not so present as the one in BMW. It feels like if you have it on your butt. Can someone detail more about this? How does it works, when, and where is located? Thanks!
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02-25-2014, 02:07 PM	#2
JordW Private 13 Rep 62 Posts Drives: BMW F21 125d Join Date: Oct 2013 Location: Devon, United Kingdom iTrader: (0)	It sounds it's best in multi storey car parks!! It is normal - it's not a dump valve just a bypass valve after the turbo not sure on the exact differences. Both let off excess pressure which is what you hear.
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02-25-2014, 02:29 PM	#3
ovekvam Brigadier General 266 Rep 3,290 Posts Drives: 2021 Galvanic Gold i3S Join Date: Jun 2012 Location: Bryne, Norway iTrader: (0)	When you go off the throttle, the Valvetronic will close the inlet valves. That will in turn take away the energy in the exhaust, which is what powers the turbo. Since the inlet valves are closed, the turbo will build excess pressure in the inlet manifold. Combined with no power from the exhaust, the turbo will stall. To avoid this, the excess pressure is simply let out by an air valve. You can see it in front of the engine, right next to the turbo. In our 116i, I can not hear it while driving, but spectators report that the car is making dump sounds when I release the throttle.
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