The 1300 was a novel car for Honda, it was a front wheel drive car, and was the largest model the company had ever produced. In 1970 a stylish coupe complemented the more conservatively styled sedan: both had a 1.3 L (1,298 cc) engine.
The 1300 was Honda's first attempt at producing a conventional sedan to compete with the Toyota Corona and the Nissan Bluebird, and the company was very ambitious, with Soichiro Honda involved in many aspects of the car's design, to include engineering efforts for both the product and assembly procedures. Changes were made multiple times, sometimes on a daily basis, which hampered efforts in production. Mr. Honda was adamant that the engine needs to be air-cooled instead of water, claiming that "since water-cooled engines eventually use air to cool the water, we can implement air cooling from the very beginning."
In May 1969 final specifications and prices for the Japanese market were announced. There were originally two engine versions, being the "Series 77" with a single carburetor 100 PS (74 kW) engine and the "Series 99" with a four carburetor 115 PS (85 kW) unit: the less powerful car was listed with four levels of trim offered, of which the top three were also available with the four carburetor engine. The manufacturer's ex-works prices ranged from ¥488,000 for the entry level "Series 77" standard saloon to ¥710,000 for the "Series 99" Custom saloon. Automatic transmission and air-conditioning were optional. Six of the seven versions offered were priced comfortably above the Toyota Corolla 4-door deluxe, then retailing at ¥520,000: for this price Toyota included delivery to the Tokyo area.
The car had been introduced at the Tokyo Motor Show in October 1968, but production only got under way during the early months of 1969. In May 1969 the Honda 1300 went on sale in Japan. It was reported at the time that launch was delayed by a couple of months because company president Soichiro Honda found the styling of the car as presented at the Tokyo Motor Show the previous year unacceptably bland and called for a redesign. It was not lost on contemporary commentators that Honda himself at the time owned and frequently drove a Pontiac Firebird, and the split air intakes on the front of the Honda 1300 as it came to market suggest that Honda design personnel were also aware of the boss's fondness for his Pontiac.
Despite enthusiastic imprecations from Honda's US dealers the Honda 1300 was not sold in the USA. Nor is there evidence of any sustained effort to sell it into Europe. Surviving examples appear mostly to be located in countries bordering the Pacific Ocean. In European terms, the car's engine size and dimensions would have placed it in the competitive sector of small 1300 cc family sedans, although its 57-inch (1,400 mm) width, reported to have been selected in order to qualify for the lower tax class on the domestic (Japanese) market, was significantly below the European standard represented by cars such as the Ford Escort of the time.
The engine was SOHC air-cooled, with a fan attached to the flywheel to pull cool air through the engine block, labeled DDAC, or Duo Dyna Air Cooling. This warm air, and additional hot air from around the exhaust manifold, was then used to heat the passenger compartment, a novel approach which was not commonly used afterward. Hideo Sugiura, then the head of the R&D Center, looked back upon the sentiment of the time: "We had a powerful company founder, Mr. Honda, who was on top of the engineering operation. He also had expertise, which he had acquired through a string of enormous successes. Having such a leader, the sentiment in the company was that we had to see it all the way through, regardless of where the road might take us. There was to be no surrender. We could not give up halfway." "Streamlining the bulky construction of the air-cooled engine, and giving it the quietness of a water-cooled engine, will create the ideal power plant...." With that concept in mind, the research engineers worked tirelessly to achieve their ideal. It was from this grueling process of trial and error that the DDAC integrated dual air-cooled engine was achieved. The initial prototype was completed in July 1968, after which dynamic performance testing, temperature measurements and other basic evaluations were conducted.
In a departure from the 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 Coupe 7 had a single Keihin carburetor and developed 100 PS (74 kW), while the engine that powered the 99 sedan and Coupe 9 was equipped with four Keihin carburetor and developed 115 PS (85 kW) 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 135 PS (at 7,000 rpm) mounted transversally in the middle. Weight was a mere 490 kg. The car only made 29 laps (out of 120) before retiring, but continued to race with some modest success through the next year.
DDAC (Duo Dyna Air Cooling system: dynamic dual air cooling system) (Japanese: DDAC), 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 introduced to the concept of air-cooled engine; the outer wall of the cylinder block is "one" to the structure in a two casting mold, with the cooling air passage in the space between, where, typically, water would be in a water-cooled engine. One fan forced cooling air through the channeled structure, while another fan helped remove the, then, heated air from the engine. Although an all-aluminum engine, this design structure did mean a comparably increased weight to the usual air-cooled design.
It was a very unique concept, the Honda engine in 1300 that lost a ball in a commercial, the Honda engine 4 for car wheels, all of which led to a shift from water-cooled air-cooled.
The car employed rack and pinion steering. At the front it had disc brakes, with drum brakes controlled via a dual-line hydraulic system at the rear. Suspension was independent, employing MacPherson struts at the front and an unusual combination of full-width swing axles and half-elliptic leaf springs at the rear.
The front suspension was substantially modified after the car's initial presentation: production cars incorporated modified front suspension geometry, a lowered steering ratio and a steering damper, intended to reduce the unusually strong self-centring propensity which was a feature of the pre-production cars originally presented to journalists. The cars as sold also incorporated a changed gear-box and final drive ratios along with resized wheels
The H1300 provided the shock needed to change Honda's operating structure. Under the new system, Honda introduced the water-cooled Life and Civic models as its new mini automobile and small passenger cars. The Civic, which was equipped with a CVCC engine in full compliance with the Japanese government's Air Pollution Control Act, drew the world's attention to Honda's engineering approach.
Those involved in the H1300 project agreed unanimously. The pain indeed contributed much to the development of Honda's subsequent, successful future automobile models. In 1973 the 1300 was succeeded by the technically interesting Honda 145, again offered as a Sedan or a Coupé. The 145's body was little changed from the 1300, but it was powered now by a water-cooled 1433 cc engine, the inspiration for the car's name. The market was not impressed by the 145: only 9,736 were produced as the model quickly found itself overshadowed by Honda's new Civic, and the 145 ended production in October 1974.
A coupé would not be produced again by Honda until 1978, when the Prelude was introduced.