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Old 01-22-2011, 05:50 PM
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Originally Posted by cambrian123456 View Post
it seems that this flap is used to make the intake manifold longer or shorter
This is the clearest explanation yet (if it's correct) of what the DISA valve purports to accomplish ...

To be exact, the DISA valve does not change the length of the intake system on the six-cylinder engines from the M52TU onwards - its function is to be open at low speeds, so feeding all six intake pipes together.

At mid-range speeds it closes, seperating the front and rear groups of three cylinders from each other. At higher speeds it opens again, joining the cylinder groups together. It therefore acts like a massive balance pipe which can be closed when required.

The effect of this is to give more mid-range torque without interfering with bottpm and top-end torque.
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