[briank]

I'm trying to find out why no manufacture has implemented variable compression ratio technology. In part load conditions most engines only have an effective compression ratio of 6:1 or less (The published compression ratio only applies in high load conditions) So this makes me think of using a sliding plate that dynamically slides in a controlled manner into the combustion chamber (to displace some of the unoccupied volume) in part load conditions bringing the effective ratio back to 9.5:1 and slides out in high load conditions. It's probably not as simple as attaching this "slider" to an accelerator cable and I see lubrication and getting really tight tolerances as one of several challenges to be overcome. While I may be over simplistic here, why this low hanging fruit is still not implemented by any manufacturer as this idea has been floated for decades.
I just found some info here. This site www dot prodrive.com/up/vcr.pdf