Nissan Dual Injection
Left: One port of the Dual Injector Right: Conventional system injecting to both ports

Nissan has announced a new Dual Injection System that is expected to be introduced in various Nissan production cars in 2010. At first you may think its something like Toyota’s D4-S twin injection system which uses one direct injector and one port injector.

But it’s not. It’s designed to be somewhere in between conventional port injection and direct injection. As the name suggests, the new system uses one injector for each port (typically 2 intake ports in a 4 valve engine) rather than one per cylinder, making it a total of two injectors per cylinder.  This system, said to be the world’s first, helps speed up fuel vaporization and reduces the amount of unburned fuel and hydrocarbon emissions.

The system has a number of benefits including, reducing the diameter of the fuel droplets by about 60%, resulting in smoother, more stable combustion, reducing system production cost by about 60% compared to direct-injection engines of similar displacement and more. Nissan says direct injection has been hard and expensive to use on small displacement engines because of high pressure pumps that complicate system design, thus making the component layout less cost-efficient.

The system also features a continuous valve timing control on the exhaust side which Nissan says is to help improve heat efficiency, reducing pumping losses and raising fuel efficiency by up to 4%, compared to Nissan’s other gasoline-powered engines in the same class. The new system also uses half the amount of rare metals in the catalyzer while maintaining the efficiency of the catalytic conversion system.