Development of a New-Generation High-Performance 4.5-liter V8 Nissan Engine

This paper describes a new 4.5-liter V8 engine, VH45DE, which was developed for use in the INFINITI Q45 sporty luxury sedan that was released in the U.S. and Japanese markets in November 1989. The many V8 engines in use around the world can be broadly devided into two categories. One category is characterized by ample torque at low engine speed and relatively large engine displacement. The other category is characterized by enhanced performance at relatively high engine speeds. The VH45DE engine is a new-generation V8 powerplant that delivers smooth power output at top-end speed and also generates ample torque at low engine speed to maintain good idle stability, and accomplishes it all with the smallest possible displacement.

Development efforts were focused on two main goals. The first was to achieve efficient intake air charging. This has been accomplished the intake air resonant point at a relatively high engine speed through appropriate intake branch and collector tuning. Additionally, higher charging efficiency at low engine speed has been achieved by using Nissan's aerodynamic intake port and the Nissan valve timing control system. These features assure high charging efficiency from idle speed to the rev limit. The second goal was to reduce losses resulting from mechanical friction. For this purpose, roller rocker arms and molybdenum-coated piston skirts are used to reduce friction. As a result, the engine provides superb high-speed power (6900 rpm rev limit) and also low-speed torque. Furthermore, the aluminum cylinder block and the high-rigidity design of the main structural parts combine to achieve good engine sound quality.