In what it claims is a first for a European automaker,Peugeot Citroen launches its 2L HPi (High Pressure injection), a direct-injection gasoline (DGI) engine.
Initial information from Peugeot indicates that the all-new HPi is a 2L DOHC I-4 that produces 138 hp and peak torque of 142 lb.-ft. (193 Nm), with 125 lb.-ft. (170 Nm) available at 2,000 rpm.
Compared to the port fuel-injected XU 2L I-4, Peugeot says the new HPi delivers 19% better fuel consumption on the EU mixed-driving cycle and is 21% better on the urban cycle.
The engine works in lean-burn mode, using stratified charge, up to a threshold of approximately 3,500 rpm. At that point and as load on the engine increases, the engine switches to stoichiometric operation. As much as 30% of exhaust gas is recirculated, which the company says not only reduces emissions but also helps to cut pumping losses.
The HPi engine also features a new, two-stage injection pump co-developed with Siemens AG. Peugeot says it is the lightest and most compact unit on the market, at 32 oz. (900 g) being half the weight of comparable existing designs. Injection pressure reaches a maximum of 1,450 psi (100 bar).
Most important, the company says it has developed an aftertreatment system capable of dealing with the excess oxides of nitrogen (NOx) present in the oxygen-rich combustion atmospheres of lean-burn engines. First, the company claims NOx is significantly reduced by high exhaust-gas recirculation (EGR) rates. But the main underfloor catalyst incorporates an NOx “trap” that stores excess NOx on a substrate treated with “Barium alkaline earthy metal,” (which the company claims “has a specific chemical affinity” for NOx), along with platinum. The platinum oxidizes the NOx on the substrate, storing it in nitride form on the barium-based material.
Then on the average of three seconds each minute of operation, the trapped nitrided NOx is released by operating the engine in “rich” mixture mode. Peugeot says, “This operation increases the concentration of carbon monoxide and hydrocarbons that act as reducers. The nitrogen oxides are then released and chemically reduced to nitrogen (N2) on the (catalyst's) rhodium.”
The engine management system automatically performs the NOx-trapping/purging function.
Peugeot says the HPi engine is being built at the rate of 200 units per day at its Tremery engine plant in France. The engine is being fitted for a variety of Peugeot/Citroen models.