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Valve On exhaust System , Whats it for ? any benefits , Louder ?

madalex Sep 25, 2007

  1. madalex

    madalex S3-less untill December

    What does a valve do on an Exhaust system ??? I was told something to do with built up pressure , Any louder , Performance gain ect
    Cheers :icon_thumright:
  2. dummi

    dummi smoking a6

    on a standard car its supposed to give back pressure at low engine speeds to give you a bit more instant torque when your engine is not loaded , it is always open when the car is under load accelerating. also reduces noise when cruising or sitting in traffic... if your car is modified just remove it for better flow
  3. LDoR

    LDoR likes his V6

    I always heard that back pressure in the exhaust was good for low down tourque but that never made sense to me. Resistence will just sap power and i read something in evo about that which says this back pressure being good for low down tourque is not true.
  4. Prawn

    Prawn My other car is a MINI!!!!

    it depends on the type of engine.

    on an n/a car, a small amount of back pressure really does aid low down torque.

    in my 1380 mini, when i get an exhaust leak (often due to it being SO low) i loose lots of low down torque due to the lack of back pressure. when i fix it, the torque appears again :)

    in a turbo car, its not the case, maximum flow is needed for power, with no back pressure at all.

    although, low down off boost, the turbo engine just acts like an n/a anyway, so in theory at least, the exhaust valve could help.

    although personally, i think thats just a gimick, id never bother.

    the back pressure arguement is true though.

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