The end and limitations of air cooled engines 

Curbside Honda 1300 99S Sedan

Honda 1300.

Honda had been dabbling in microcars as a sideline to its fantastically-successful motorcycle business for a few years. But these were just a curiosity outside of Japan. Soichiro Honda, the founder and master of the Honda company, wanted to enter the big leagues. He wanted to manufacture a car that could be sold outside the home market in large numbers. Something that would compete with the Toyota Corona and Datsun Bluebird.

With the exception of a few water-cooled Formula 1 cars, Honda built nothing but air-cooled engines for its motorcycles and cars through the 1960s. Soichiro Honda loved air cooled engines. “Since water-cooled engines eventually use air to cool the water, we can implement air cooling from the very beginning,” professed Mr. Honda. And he wasn’t taking no for an answer, for he personally oversaw the engineering of the new 1300 automobile.

Offered as both a sedan and a sporty coupe, the new Honda 1300 bristled with innovations. It was one of the very few front wheel drive cars in its class. It had disk brakes in front and four wheel independent suspension. This was heady stuff for a Japanese manufacturer at that time. And of course, it featured an air-cooled engine, mounted transversely at the front of the car.

The fact that it was an inline air-cooled four cylinder engine was not remarkable. This had been done before. But the engine was nevertheless notable for two reasons. (1) the technology employed for cooling the engine was both strange and unique, and (2) it was ridiculously powerful for its size.

Soichiro Honda knew that a noisy engine would not be acceptable for a world class car. And air-cooled engines have a reputation for noise due to the resonances of their cooling fins and lack of water jackets to dampen miscellaneous vibrations. So he drove his engineers crazy with all kinds of ideas to overcome these problems.

Instead of relying on long, thin cooling fins, his engineers specified short stubby ones shaped with curves and waves to suppress harmonics. The blower fan had short blades for the same reason. But what really made the 1300 engine so unique is that the engine block had cast-in airflow jackets, rather than sheet metal shrouds, to direct the cooling air around the heads and cylinders. And the jackets were ribbed, internally, to further exchange heat with the cooling air.

Curbside Honda 1300 Engine 1

If you look at the exterior of the block, you will see cooling fins. But these are not on the cylinder barrels or heads. They are on the exterior of the cooling jackets.

The castings were in aluminum, of course, and were intricate to the extreme. It must have cost Honda Motor Company a small fortune to build each one.

The 1300 was available in two series, the 77 Series with 100 horsepower; and the 99 Series offering 115 horsepower. That’s 115 horsepower from an engine with a displacement of only 1,300 cubic centimeters (79 cubic inches).

Curbside Honda 1300 Engine2

How in the world did they do it? Well, this was basically a little racing engine, with an overhead camshaft, four Keihin carburetors, hemispherical combustion chambers, and dry sump lubrication system. Peak power was delivered at 7,300 RPM. It combined all the best of Honda’s motorcycle and Formula 1 racing experience.

Soichiro Honda was entering his 60s during the design phase of the Honda 1300 and he evidently saw this project as his pièce de résistance. It was the last engineering project he would ever lead. He drove his engineering staff to near mutiny with design changes even after the production line started rolling. Working from 5 AM to midnight every day, some of the workers were suffering from sleep deprivation, even falling asleep in the men’s room.

So, if the Honda 1300 was such a master piece, why don’t we hear about it today?

There are several reasons. It was more expensive to buy than similar-size cars in Japan. It was more expensive to make than it was to buy. And for all its’ engineering innovation. the little air-cooled engine turned out to be heavier than expected. The car was hard to steer and hard on front tires.

The Honda 1300 was sold in several countries around the Pacific Rim, (most notably Australia and, of course Japan). But it never made it to Europe and the Americas.

In 1973, Honda replaced the 1300’s air-cooled engine with a water-cooled fuel-injected variant which held things over until the introduction of the wildly-successful Honda Civic. And that was the end of Honda’s foray into air-cooled engines for passenger cars.

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