The medium duty commercial vehicle “ISUZU FORWARD” powered by the newly designed 6HE1 six cylinder engine was placed on Japanese market in April 1990. At the same time the engine family of the four cylinder version 4HF1 engine mounted in the light duty commercial vehicle “ISUZU ELF” was introduced in Japanese market in August 1990. These H-series engines are successors to the B-series engines, which have been used worldwide for vehicles, industrial machinery and boats.
The basic structure of OHC and ladder frame of these engines made it possible to improve the design of the inlet and exhaust ports and valves, and improve the stiffness of the cylinder block and the cylinder head. In turn this provides higher performance, durability and reliability.
This paper describes the special features and construction of these new H-series engines, together with newly adopted technology.