Please Enjoy This Japanese Racing Shop Building an Engine

OS Giken’s S30 Z project is getting a detailed look as a Japanese racing shop builds an engine from scratch in a video shared on Inside Japanese Factories. The build focuses on an L-Series inline-six topped with OS Giken’s TC24-B1Z head, described as a modern reissue of the TC24-B dual-overhead cam design created by founder Masaharu Okazaki in the 1970s. The company notes only nine original TC24-B1 heads were made, and that the B1Z returned in 2017 with updates to leverage manufacturing advances over the following five decades. Despite the factory’s CNC machines and CAD-based systems, the engine assembly is small-scale and largely manual, without computerized torque-tracking tools. The process includes cleaning the original L-Series block, installing new parts such as the crankshaft, pistons and connecting rods, porting and polishing the head, then testing on an engine stand. The full build took four months before installation in the Z.