M Engine developers have been dreaming of a variable for a long time Compression, with which engines can be optimally adapted to load conditions. Variable compression also opens up new potential for savings in emissions and fuel consumption without having to forego top performance. There have already been many approaches, but no project has made it to series production.
More performance, less consumption
After Nissan's premium brand Infiniti showed the Motior at the Paris Motor Show in 2016, Nissan has now presented details of the new, production-ready VC-T engine with variable compression at the engine symposium in Vienna. The new engine is said to contain over 300 new patents. The four-cylinder with turbocharging has a variable stroke and can thus vary the compression ratio between 8: 1 and 14: 1. The stroke height of the pistons is controlled by a multi-link system that can move the pivot point of the connecting rod base via an additional shaft at the bottom of the engine. The adjustment is infinitely variable. Sounds a lot like a variation of the Atkinson Motors , which works with an additional crank arm and another connecting rod between the crankshaft and piston. Nissan already had the corresponding patents protected in 2001 and 2008 under the numbers US 6505582 B2 and US8087390 B2.
The variable compression in the VC-T engine is combined with variable valve control for inlet and outlet and Direct injection.
The two-liter four-cylinder should deliver 272 hp and 390 Nm of torque. In addition, the VC-T engine is said to be around 27% more economical than the 3.5-liter V6 it replaces.
The Japanese are planning the first series use of the VC-T engine in 2018. It it can be assumed that this technology will also be rolled out in models from the Renault-Nissan alliance and will also be adapted for other engines.
Variable compression is not new
Saab already had a test engine with variable compression at the turn of the millennium presented. At the time, the SVC engine relied on a swiveling cylinder head to vary the compression. The 1.6-liter five-cylinder with mechanical supercharger developed 225 hp and provided 305 Newton meters, but never got beyond the test stage.
At the 2015 Vienna Motor Symposium, engine developer IAV presented a system that moves the entire cylinder head including the cylinder liners by a maximum of six millimeters relative to the crankcase via two shafts.