Quote:
Originally Posted by t vago
May well be. It depends on if the increased vacuum developed offsets the initial air pressure as the intake valve opens.
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Yes, this is why I speculate that any sort of possible improvement would be very small if existent at all.
drmiller, the idea is that the cylinders do not draw air in a constant stream, but a large plenum plus single throttle tends to average out the pulses.
If we're going by the pumping diagram, the difference is that normally, when the intake valves open the piston is immediately exposed to manifold vacuum, whereas in this situation the cylinder is at atmospheric pressure. As the piston draws air in, the pressure will fall more slowly because it starts out closer to atmospheric, but then you end up with deeper vacuum. So what it does is sort of chop a "triangle" off the bottom left of the pumping loop, but extends its height downward. It gets a bit more complicated as if the temperature changes then the compression curve looks a bit different as well, so it's rather hard to say, but I have a hunch it might have a noticable effect.
I think it would be cool to see data from someone who has swapped ITBs into their car.