Development of New I4 2.5L Gasoline Direct Injection engine 2019-01-1199
The New 2.5L I4 engine called PR25DD has been developed for 19MY new ALTIMA as a replacement of current QR25DE. The scope of this engine is US D-sedan market, and the concept is to achieve good acceleration, fuel consumption and NVH performance with state of the arts technology. Major dimension like boa and stroke are carried over from QR25DE, however development had started from reviewing the basic specification such as combustion chamber design, engine mounting structure for keeping competitiveness.
PR25DE major engine system follows Nissan new engine concept with DIG, electrical VTC, mirror bore coating, cooled EGR, and variable displacement oil pump. In addition, this engine added the plastic intake port and the exhaust manifold integrated cylinder head.
The plastic intake port is the world 1st item for knock performance improvement. This plastic port is inserted into the intake port, and it can make air-layer. Air layer can reduce intake air temperature then combustion efficiency is improved because ignition timing can be advanced at high load area. The exhaust manifold integrated cylinder head is key part to comply US emission regulation. Fast temperature rising rate due to exhaust manifold integrated cylinder head can make catalyst active fast.
Due to these items, PR25DD can achieve good acceleration, fuel consumption and NVH performance at the best level, and this can improve real-world usage steadily. This paper describes details of this new engine with highlights of the applied technologies which have contributed to the highly balanced performances of the engine