Development of New I4 2.5L Gasoline Direct Injection Engine 2019-01-1199

A new 2.5L 4-cylinder direct-injection engine (PR25DD) was developed for use on the new 2019 model year Altima as a successor to the QR25DE engine mounted on the previous model. The development concept defined for this new 4-cylinder engine was to achieve acceleration, fuel economy and noise, vibration and harshness (NVH) performance at the highest possible levels by incorporating the latest technologies, including a world’s first application.

The PR25DD engine continues Nissan’s new engine concept of recent years with regard to the basic engine systems, including the use of direct injection, an electrically operated valve timing control (VTC) system, cooled exhaust gas recirculation (EGR), an integrated exhaust manifold, mirror bore coating and a variable displacement oil pump [1]. In addition to these features, it also adopts a resin intake port. The resin port is inserted into the intake port cast in the cylinder head, thereby forming an air layer between the intake air passageway and the head inner wall so as to suppress the rise in intake air temperature. This world’s first application of a resin intake port improves anti-knock performance, thus contributing to improvements in combustion efficiency and power output.

As a result, reliable improvements were implemented in the practical operating range to achieve class-leading performance in the areas of power, fuel economy and NVH. This paper describes in detail the principal technologies adopted to achieve these performance improvements.