The life of an exhaust system
For naturally aspirated engine, the intake manifold plays a huge role in performance. The intake runner length would influence performance including fuel consumption in the Low, Mid and High power bands. But being that intake manifold is typically made of plastic - it is not possible to vary the length to suite the traffic situation or your mood.
Or so it seems....
BMW has ingeniously able to vary the length by using a series of air passages within the intake manifold that makes use of flaps that open or close based on how you accelerate or decelerate. This mechanism is call DISA.
The number of flaps ranges between 1-2. A 3 stage manifold would have 2 flaps and a 2 stage manifold just a single flap.
When these DISA flaps start to fail - typically it would remain open when it should be shut - the intake runner length would be inappropriate. E.g. a DISA flap that remains open would affect power delivery in the Low rpm range - robbing the engine of it power and increases fuel consumption.
Bmwpartsco.com stocks a wide range of DISA flaps and gaskets and would deliver it right to your door step.
Just key in your VIN on http://www.bmwpartsco.com and the DISA specific to your engine can be found.
Talk to our product specialist if you need further assistance.
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