where does the air go? if the air is not vented, it stays in the pipe. therefore once you jump onto the throttle again and the throttle body opens, and because the pipe is already fulled with air, it goes straight into the throttle body, unlike if you vent it.
this is one of the main reason why pro. drifters don't run bov as it helps with lag between gear changes *weather its noticeable or not is another issue*
also how fast is the turbo rotating/spinning ? 100,000rpm or more, do you think that the amount of air remaining in the pipe has enough force to slow down the turbine when it is speeding at such a high rate?
yes its physic, the air must apply a force on the turbine blades. the turbine blades are rotating which means they also have a force...
so we have:
Air:
F= ma
m= mass of the body (kg)
a = resultant acceleration of the body (m/s^2)
now because the turbine blades are rotating they have a torque.
t=mr^2a
m=mass(kg)
r=radius(m)
a=angular acceleration (rad/s^2)
but that is assuming the turbine blades are a point mass system and we don't consider the mass moment of inertia
what im tring to get at is that one force will be alot larger than the other, so the impact of the small force on the larger force won't be that great....
also their are other issue to consider but its late and i can't remember this stuff off the top of my head would have to go grab my uni books and start quoting lines etc
just to summaries my point. the Force exerted by the air is not great enough the reduce/impact the turbine blades , due to the relative large force it creates (creates is not the best word but you get my point)