Arguably the most significant debut of the 2016 Paris auto show is Infiniti?s QX Sport Inspiration concept with its nearly production-ready, variable-compression-ratio four-cylinder engine (VC-T), slated to go into the next QX50 crossover in 2018. But Nissan isn’t the only player in hot pursuit of this technology, a holy grail of combustion control that engineers have been seeking for nearly 100 years. Most major automakers are also working toward this efficiency-boosting trick for its engines in the face of ever-tightening emissions standards worldwide.
Another variable-compression engine trying to work its way toward production comes from a small French company, MCE-5 Development. It employs 49 people and was formed in the year 2000 specifically to develop this technology, which it calls VCRi. As seen in the photo above, and similar to Infiniti?s solution, MCE-5?s engine employs a rotating link between the connecting rod and the crankshaft to vary the compression ratio between its two extreme values. But the mechanism on the right side that’s used to rotate that link appears, at first glance, to be a second row of pistons. These ?control jacks,? as MCE-5 refers to them, ratchet up or down using harvested inertial energy from the pistons. And, unlike the Infiniti engine, this one can vary the compression ratio independently for each cylinder. We met with MCE-5?s CEO Henri Trintignac at the Paris show, who unsurprisingly made a host of bold claims about his...