550i exhaust question
12-06-2009, 08:11 PM
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Originally Posted by GENEaTALS' post='1069046' date='Dec 6 2009, 11:59 PM
12-06-2009, 09:24 PM
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My Ride: 2006 BMW 550i
Originally Posted by VTGT' post='1069040' date='Dec 6 2009, 10:47 PM
I bet the flap is closed just to keep it quiet. Does anyone know if there is a flapper mod to be able to control the flap manually or electronically like you can do in the VW R32 and other cars with the flapper setup?
Here is the official BMW explination:-
Thank you for your email to BMW Customer Information.
We can advise that the exhaust flaps adjust at differing engine speeds in order to make the most effective use of the exhaust silencer. When the vehicle is running at idle or at low RPM, the flap ensures that the exhaust gases use as much of the silencer's volume as possible, keeping exhaust noise down, e.g. when you're in slow traffic or driving in high gear.
Whereas when the vehicle is running at high RPM, the exhaust flow characteristics are adjusted by the flap to give the exhaust gases a more direct route through the silencer, thus using less of its volume. This also has the effect of allowing the engine to rev more freely as there is less restriction on the exhaust flow.
The primary reason for the flap is to make the most effective use of the exhaust silencer volume at differing engine speeds.
We trust this information is of some assistance to you but if we can help you further at any time, please do contact a member of the BMW Customer Information Team.
Yours sincerely
BMW Group UK
Elfriede McNeal
Product Information Advisor
Ellesfield Avenue
Bracknell
RG12 8TA
Tel: 0800 325600
Fax: 0870 5050 206
Email: customer.information@bmw.co.uk
Website: www.bmw.co.uk
Thank you for your email to BMW Customer Information.
We can advise that the exhaust flaps adjust at differing engine speeds in order to make the most effective use of the exhaust silencer. When the vehicle is running at idle or at low RPM, the flap ensures that the exhaust gases use as much of the silencer's volume as possible, keeping exhaust noise down, e.g. when you're in slow traffic or driving in high gear.
Whereas when the vehicle is running at high RPM, the exhaust flow characteristics are adjusted by the flap to give the exhaust gases a more direct route through the silencer, thus using less of its volume. This also has the effect of allowing the engine to rev more freely as there is less restriction on the exhaust flow.
The primary reason for the flap is to make the most effective use of the exhaust silencer volume at differing engine speeds.
We trust this information is of some assistance to you but if we can help you further at any time, please do contact a member of the BMW Customer Information Team.
Yours sincerely
BMW Group UK
Elfriede McNeal
Product Information Advisor
Ellesfield Avenue
Bracknell
RG12 8TA
Tel: 0800 325600
Fax: 0870 5050 206
Email: customer.information@bmw.co.uk
Website: www.bmw.co.uk
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