how exactly do the disa valves increase hp by 40

[solo_the_lad]

I don't get it

also side note, if the disa's sole effect is on the air intake manifold (this part I know), then would forced induction (i.e. supercharger) render the disa valves useless? im guessing the disa's meter the air in some way, and so I would think forced induction would make the disa's pointless. Ultimately what im wondering is would a supercharged 3.0si make more power than a 3.0i ?

[Usel]

The disa valve is there to increase torque at lower rpm rather than to increase the power at high rpm.

At 4k rpm and over the disa would be in the normal position as if it was never there. The disa valve only becomes a thing at lower rpm.

Usually when they break people find that performance isn't effected above 4k rpm but below 4k the engine is boggy and unresponsive.

Simplest way I can explain it really, it's a bit like a choke on a 2 stroke brush cutter or chainsaw but works when the engine is hot and not just for starting the engine.

P.S it could be 3k rpm when the disa comes into play, I can't remember

[enuff_zed]

Do you remember the old F1 cars with Ford DFV engines? Depending on the circuit characteristics they would fit different length intake trumpets to them to alter the torque characteristics.
Put very simply, this is what the DISA valve does. It alters the intake path to optimise torque across the rev range.

[B21]

Supercharger will always out run any normally aspirated car with whatever fancy induction tricks..

More Boost Mr Sulu!