previous Honda practice of using roller bearings on the crankshaft, the 1300 engine had more conventional plain bearings. Two versions of the engine were available. The engine fitted to the 77 sedan and Coupé 7 had a single Keihin carburetor and developed , while the engine that powered the 99 sedan and Coupé 9 was equipped with four Keihin carburetor and developed at 7,300 rpm. Initial skepticism was expressed among competitor manufacturers and in the trade press concerning Honda's power output claims for the car, but those who drove it reported an engine that would freely rev to an indicated 8,000 rpm and remarkable performance for a 1,300 cc engined car: the factory figure at launch for a standing quarter-mile acceleration test of 17.2 seconds was felt to be not unreasonable. The engine was a dry-sump design with a pressurized oil system feeding from a tank. An electrical fuel pump was another high-tech novelty which would eventually be common. The electrical system was another matter — it had a separate redundant set of wiring on each side of the car. The high-revving character and dry-sump oil system both meant that the 1300's engine should be a natural for racing, and soon the RSC (Racing Service Club, Honda's competition department) built the mid-engined, tubular framed Honda R·1300. Next, in the 1969 Japan GP the similar Can-Am style Carman-Apache made its racing debut, with a Honda 1300 engine tuned to at 7,000 rpm, mounted transversally in the middle. Weight was a mere . The car only made 29 laps (out of 120) before retiring, but continued to race with some modest success through the next year. The engine block was also used to create the 2991cc V8 used in the Honda RA302 that was raced at the Formula One racing car produced by Honda Racing, and introduced by Honda Racing France during the 1968 Formula One season. The car was built based on the order by Soichiro Honda to develop an air-cooled Formula One engine. DDAC DDAC (Duo Dyna Air Cooling system: dynamic dual air cooling system) (), was the name of the air-cooling system presented by Honda in 1968. It had a double wall structure, thus, its name. In this engine, the cooling "water jacket" was combined with the concept of air-cooled engine; the outer wall of the cylinder block is part of the structure in a two casting mold. It