Search Results

The horizontally opposed family of engines manufactured by Fuji Heavy Industries in Japan have been mass produced with a variety of cylinder block designs and Aluminum alloy casting techniques. These include closed deck configurations by a semi-permanent mold or low pressure casting technique, open deck configurations by a high pressure diecasting method, and both open and closed deck configurations by a hybrid medium pressure casting process. In this paper we review our experience with each production process/engine design combination. Special attention is paid to cylinder liner technology, coring methods applied to form the water jacket, oil galleries and other cavities, overall casting productivity and the contribution of casting design to end product performance.

Since the intake and exhaust valve timings that provide the best fuel economy, idle stability, or highest power change according to the engine operating zone, a variable valve timing system is very beneficial. Also, roller followers, which reduce mechanical friction loss of a valve train mainly at low engine speed, are commonly used to improve fuel economy in urban driving conditions. This paper presents a newly developed 4-valve variable-valve-timing mechanism with roller followers. Different intake- and exhaust-valve timings and lifts are selected independently, depending upon whether engine speed is low or high. Durability tests of running at maximum engine speed and switching between low- and high-speed cams were conducted and good test results were obtained.

For the 1990 model year Fuji Heavy Industries will introduce Subaru “Legacy” with a newly designed horizontally opposed 4-valve engine series including a 2.2 Lt for the US market. The new engine series which has been named “Boxer” to symbolize power has been designed and developed making the best use of the advantages of horizontally opposed engines and our twenty three years experience in producing them. The major advantages of horizontally opposed engines are low noise and vibration, with high specific power and design flexibility which are well featured in these new engines. This paper is intended to provide a brief overview of the new engine program with descriptions of unique design features.