The "Quasi" part of QNP is the fact that it works as
F = MV
rather than
F = MA
It should also be noted that engine sizes are measured the same way that other components are.
In QNP the sizes are presumed to be masses, rather than volumes or some other unit of measure. Doubling the mass of your engine room means doubling the number of engines, and thusly producing twice the thrust. Twice the thrust means being able to move twice the amount of ship at the same rate.
Newton says: Twice the engines + twice the ship = same speed
Your system as described would indicate that component sizes are linear dimensions, and that would disconnect a ship's "size" from its mass.
As far as gameplay, your system does sound like a quite nifty (and creative) way to diversify the hulls used in a game.
Some people tend to think that everything good has been done already after 6 years. Congratulations for proving them wrong! 