Car manufacturers are taking downsizing very seriously now as a solution to reduce their overall fuel consumption and CO2 emission. Fiat has already launched a 2-cylinder engine for the 500 models, and now Nissan has come up with a 1.2 liter 3-cylinder unit. They say this supercharged engine delivers the same power as a 1.5 liter, but CO2 emission of 95 grams per kilometer.
The HR12DDR will power the new generation Nissan Micra which is known as March. To maximize its efficiency, this engine features Miller cycle, gasoline direct injection system (DIG), and a highly efficient supercharger, in combination with an Idling Stop system. If you have no idea what any of that means, here’s some explanation:
By adopting the Miller cycle, in which the power stroke is enhanced by the compression stroke as a result of delaying the closing timing of the intake valve, the thermal energy of the fuel is converted to kinetic energy much more efficiently than it is with regular 4-stroke cycle engines, and pumping loss caused by intake manifold negative pressure has been reduced.Moreover, the highly compressed and high-temperature air-fuel mixture is cooled by the latent heat of the vaporization of fuel directly injected into the cylinder, and the temperature of the combustion chamber is lowered by adopting a piston-cooling channel and sodium-filled valves to control detonation. These technologies have enabled a compression ratio of 13 for improved combustion efficiency.
The supercharger is equipped with an automatic on/off clutch, which means that both high fuel efficiency and high engine performance can be achieved by automatically switching off supercharging while driving at low speeds, such as on city roads.
Moreover, adoption of a hydrogen-free diamond-like carbon (DLC) coating for the piston rings and a variable displacement oil pump helps to reduce friction by up to 30%, compared with conventional 4-cylinder engines with similar performance levels