The Tatra T600, nicknamed the Tatraplan, was a large family car in the late 1940s. It has always been powered by an air-cooled, four-cylinder petrol engine. However, the Kopřivnice-based car manufacturer also flirted with the idea of a diesel engine. And even built three such prototypes in 1952.
The 1950s were marked by old regime trials, monetary reform, nationalization and Communist rule. Tatra was forced to give up passenger car production for a short while to focus on trucks. However Tatra engineers were working on some projects even then – including a diesel-powered Tatraplan.
In the 1950s, you would find it difficult to find a diesel engine under a car’s hood. Mercedes produced the 170V diesel, Fiat offered the 1400 diesel and Borgward-Hansa the 1800 diesel. Peugeot returned to the field in 1959 with the 403 diesel.
Against this backdrop the efforts of Czechoslovak Tatra engineers is even more commendable. Though they had no chance for serial production, they worked on prototypes.
The newer Tatra T603 was still only on the drawing boards, and production of the old T87 was about to end. The T600 Tatraplan was a cheaper 4-cylinder model introduced in 1948. It maintained the concept with an air-cooled engine at the rear and aerodynamic shape.
Although Tatra produced trucks with diesel engines, due to their purpose, not a single part of them was suitable for the light, aerodynamic Tatraplan. There was no budget for the development of an entirely new diesel unit. And so Kopřivnice decided to derive diesel from a four-cylinder petrol engine. So they produced the first flat diesel engine in history, whereas the Tatraplan had a horizontal 4-cylinder with counter-rotating pistons and air-cooling. Of course, the conversion to the diesel cycle required significant adjustments.
The cylinder head remained intact, but in the spark plug, the designers screwed in a chamber for indirect injection of diesel. The connecting rod bearings and the crankshaft also had to be reinforced to withstand higher pressures. The compression ratio was also changed so that the engine could ignite the diesel. In place of a fan an injection pump was installed. The engine was cooled by two smaller axial fans on the sides. However, not everything went smoothly.
They tested different chamber shapes with varying ratios of compression, different piston shapes or different valve countersinks. The engine had problems with the diesel injectors, which became too hot. However, they fine-tuned it to the operational phase. The engine had an output of 30.9 kW at 3,300 rpm, which was 42 hp, ten less, compared to the 4-cylinder petrol unit. Good aerodynamics helped in particular, so the Tatraplan Diesel reached a top speed of 130 km/h. Averaging 100 km/h on a motorway was not a problem at all.
The diesel engine consumed about eight to nine litres of diesel per 100 km. However, the coin’s flip side was its high noise level, especially at speeds above 60 km / h. Tatra could gradually improve all this, but at this stage, the project was over. In essence, it was an answer to a question that no one had asked. The diesel market certainly did not thrive.
It did not make much sense to invest additional resources in the development of such a model. Besides, Tatra had to complete work on the new Tatra T603 and, in the euphoric times of building socialism, including large constructions, ensure the production of a sufficient number of Tatra T111 heavy trucks.