One frame, five engines.
The shiny bodywork of this Bugatti racing car disguises a truly remarkable machine. It is the so-called ‘Frame 6’, first built in 1935 and then continually developed by the Molsheim factory to meet a host of different racing and record-breaking formulae – and then after World War II receiving the unique experimental composite engine that had miraculously survived, unrecognised, in America.
The story of Frame 6 starts in 1935. On a new Type 59 frame with its distinctive lightening holes, Bugatti built its first larger-engined Type 59 evolution, the Type 59/50S. Still as a classic offset single-seater, it was fitted with a straight-eight 4.9-litre Type 50 engine in an ultimately vain attempt to compete with the new cars from Mercedes-Benz and Auto Union. Raced by Robert Benoist in the Grand Prix de l’ACF on 23 June 1935 at Montlhéry, it notoriously lost its bonnet and eventually retired on lap 16 with a broken rear axle.
Bugatti then converted Frame 6 into a true single seater and fitted it with the new supercharged aluminium-block 4.7-litre 50B I engine. It appeared only in practice at the Monaco Grand Prix in April 1936, still with its original Type 59 gearbox. By the time of the Swiss Grand Prix in August it had received the newly designed and excellent synchromesh gearbox also used in the Type 59 sports cars, but Wimille had to give up on lap 3 with a broken gear lever. Better news for Bugatti came in October 1936 when Wimille brought the car home second to Nuvolari’s Alfa Romeo 12C-36 at the Vanderbilt Cup in New York.
The new formula for 1938 specified 4.5 litres unblown and 3 litres blown – and Frame 6 was thus fitted with the naturally aspirated 4.5-litre 50B II engine for the 1937 Million Francs prize attempt. Benoist failed to meet the speed target and the funds for development of a competitive French contender went instead to Delahaye.
The final engine change in the pre-war period came in 1938, when a supercharged 3-litre 50B III engine was fitted to the single-seater for two races, at Cork and Reims – hence the car’s present-day name of ‘the Cork car’. The bodywork was further refined with the attractive front cowling that the car still carries. Despite failure to finish in either race, it showed some promise in the hands of Wimille.
After the war the car went through many hands in Europe and the USA. It was finally restored to its former glory and is now in the hands of an Austrian collector. But how did it receive yet a fifth engine? In 1938 Bugatti created, in complete secrecy, a remarkable composite version of the 3-litre 50B III engine. Everything about it was designed to serve its purpose with the minimum of weight. There was no cast block; instead, steel cylinders were bolted on top of the crankcase. Eight individual cylinder heads were cast in bronze, for excellent heat dissipation. The whole was enclosed by duralumin side plates, bent and machined to size and closed with duralumin end plates, to create the water-tight cooling passages.
The engine was never raced. It went to the USA after the war in a load of many tons of Bugatti spares bought from the factory. Only during the restoration of Frame 6 was it recognised as the composite engine – and was fitted to this car.
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