Section 8. Debut of the Toyopet Crown, a Full-Fledged Passenger Car

Item 2. Development of Large Trucks, Four-wheel-drive Vehicles, and Diesel Engines

Development of the C diesel engine

When sales of the DA60 truck were launched in 1957, the Ministry of International Trade and Industry opposed the new vehicle in the interest of protecting existing diesel truck manufacturers. Senior Managing Officer Eiji Toyoda was summoned to the Ministry's Bureau of Heavy Industry and requested to discontinue production and sales.

Starting before the war and continuing into the postwar period, Toyota Motor Co., Ltd. had been obliged on several occasions to shelve the development of a diesel-engined truck on the grounds that it would cause excessive competition. Senior Managing Officer Eiji had submitted diagrams for an automobile diesel engine as his university graduation project and, after joining the company, had continued to pursue, among other projects, the research and development of a Junkers-type diesel engine. He was not prepared to abandon an ambition he had thus nurtured for many years, especially since he had completed the prototype of a compact diesel engine for a passenger car in the 1,500cc class (development code number: 3E; engine model: C) at the end of 1955 and preparations were now under way for the sales launch of a vehicle fitted with the engine. The development of this engine had been progressing on the basis of research into fuel atomization carried out at a university research laboratory by Shoichiro Toyoda, Director and General Manager of the Inspection Department.

Meanwhile in February 1955, Nippondenso Co., Ltd., as mentioned previously, had received government approval and begun production of an injection pump, the technology for which had been introduced by Robert Bosch GmbH. It was out of the question under these circumstances to obey the Ministry's request to abandon production and sales.1

Toyota Motor Co., Ltd. confirmed that the project would proceed as planned and a prototype of the Model CS20 Crown diesel vehicle fitted with the Model C compact diesel engine for passenger cars was exhibited at the 5th Tokyo Motor Show held from October 11-20, 1958. Sales of the new vehicle model began on October 19 of the following year.

The Model C compact diesel automobile engine fitted in the Crown diesel prototype-at the time the world's smallest diesel engine for a passenger car-was awarded a medal by the Japan Society of Mechanical Engineers in 1958 in the product category in recognition of its originality and excellent performance.2

Launched at the same time as the Model CS20 Crown diesel engine was the Model 2D diesel engine (6,494 cc, 130 hp/2,600 rpm), which had an enlarged bore compared to the Model D and increased displacement volume and output. The initial Model D and Model 2D diesel engines experienced some problems with the wear resistance and durability of components, but these issues were resolved with the cumulative effect of steady improvements.

Later, as truck load capacity grew from 5 or 6 tons to 8 and then 10 tons, there was less demand for Model D diesel engines, which were designed for trucks with a 5- to 6-ton load capacity. On the other hand, passenger car demand grew rapidly, which led to the focus of engine production shifting to the passenger car sector. In January 1966, the year when the first-generation Corolla economy car appeared, assembly of the Model D diesel engine was transferred to the Kyowa Plant of Toyoda Automatic Loom Works, Ltd., where all production processes from casting to machining and assembly were integrated.

Meanwhile, the appearance of the Model RS31 Crown 1900 Deluxe fitted with the Model 3R engine (1,897cc, 90 hp/5,000 rpm) in October 1960 threw into relief the power limitations of the Model C diesel engine fitted in the Model CS20 diesel Crown, which had a maximum output of 40hp. The Model 3R engine, which took over without alteration the cylinder block of the R engine designed for the 1,500cc range, was an experimental engine that adopted a swirl-type combustion chamber (Table 1-38). To raise engine output, the cylinder block needed to be redesigned, and production of the Model C diesel engine was ended in 1961.

Table 1-38. Specifications of the C Diesel Engine (1959)

4-cycle, swirl chamber, inline 4- cylinder
78×78 mm
Total engine displacement volume
Compression ratio
Maximum output
40 hp/4,000 rpm
Maximum torque
8.5 kg-m/2,400 rpm
Source: Toyota Engineering Society's, Toyota Technology, September 30, 1959

Drawing on the experience gained with the Model D engine and the Model C diesel engine, in 1964 Toyota developed the Model J diesel engine with equal output to the Model 3R. Responsibility for production was assigned to the Kyowa Plant of Toyoda Automatic Loom Works, Ltd.

From then on, Toyoda Automatic Loom Works, Ltd. continued to handle diesel engine production for Toyota vehicles and became one of the world's leading diesel engine manufacturers when measured in terms of number of units rather than displacement volume.

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