[ksa8907]

Ideally, assuming this idea can work, i think anticipating the spring compression and then increasing the compression ratio back up to what is common on todays engines could mean big power numbers. You would effectively be getting a longer stroke out of any given engine.

Another effect, as the piston is decelerating toward bdc on the intake stroke, it may also compress the spring at higher engine speeds allowing for a larger effective displacement than static.
...maybe not since the spring would definitely be compressed on tdc.