From the November 2016 issue
For ages, automakers have been searching for a practical means of varying an engine?s compression ratio on the fly. How hard the air?and sometimes the fuel?is squeezed before ignition plays a crucial role in overall efficiency: Compressing the mixture as much as possible without detonation yields a longer expansion ratio and more power for every increment of fuel consumed. Since the compression ratio is determined by basic engine geometry (the cylinder volume with the piston at the bottom of its travel versus the top), that isn?t easily changed. One expedient now in wide use is combining the Atkinson cycle with variable valve timing. But Infiniti has made a ­significant stride with its Variable Compression-Turbo (VC-T). This boosted 2.0-liter four-cylinder, the product of two decades of research and 300 patents, will power unspecified Infiniti models beginning in 2018. Here?s how it works: ...