Nissan Introduces New Dual Injector System for Improved Fuel Efficiency in Small-Displacement PFI Engines

14 July 2009

Nissan’s Dual Injector. Click to enlarge.

Nissan Motor Co., Ltd. has developed a Dual Injector system designed to improve fuel efficiency in small-displacement gasoline engines using port fuel injection (PFI).

While most current port fuel injected gasoline engines utilize one injector per cylinder (furnishing fuel to two intake ports), the new Nissan Dual Injector system uses an injector for each intake port—i.e., doubling the number of injectors per cylinder.

Fuel Injection Comparison (Left: One port of the Dual Injector Right: Conventional system injecting to both ports) Click to enlarge.

The novel fuel delivery system, the first for a series-production passenger car according to Nissan, reduces the diameter of the fuel droplets by about 60%. This speeds up fuel vaporization, reducing the amount of unburned fuel and reducing hydrocarbon emissions.

Nissan says it will introduce the new system in production vehicles starting early in fiscal 2010.

The system also adds continuous valve timing control on the exhaust side to conventional intake-side control, improving heat efficiency, reducing pumping losses and raising fuel efficiency by up to 4% (compared with Nissan gasoline-powered engines in the same class) in sync with the dual injectors.

Direct-injection systems, which inject fuel directly into cylinders with and provide fuel economy and emissions benefits, are difficult to use on small-displacement engines because they require a high-pressure pump that complicates system design, making component layout less cost-efficient.

In contrast, the Nissan Dual Injector system is lighter and structurally simpler because it furnishes fuel at normal pressures, reducing cost by about 60% compared to direct-injection engines of similar displacement.

The new Dual Injector system also uses half the amount of rare metals in the catalyzer while maintaining the efficiency of the catalytic conversion system. That number could potentially be reduced to 75% in combination with the ultralow-rare-metal catalysts that were introduced in 2008.

We consider it important to further improve the fuel efficiency of gasoline engines as demand for gasoline and other internal-combustion systems continues to increase around the world. By widely applying the Dual Injector system on small-displacement engines, we hope to help reduce CO2 emissions and conserve rare metals.

—Shuichi Nishimura, Corporate Vice President, Nissan Powertrain Engineering Division