Bugatti 57 Atlantic

Jean’s Bugatti

The Bugatti 57 was officially presented on the Paris motor show in 1934. The model was launched in three versions: a 4-door sedan called “Galibier”, a 2-seat coupè “Atlante” and a 4-seat convertible called “Stelvio”. Then in 1936, the model 57 was also presented in a version with the “S” type chassis. The range of bodies offered by Bugatti expanded by the introduction of a 2-seat spider “Aravis”, a 2-door 4-seat “Coach ventoux” and a super-racing “Atlantic” based on the model “S”. The last body typology, a cabriolet called “Aravis”, was presented in 1938.
The bodies were designed by Jean and his colleagues and physically produced by Gangloff Fréres. Needless to say that it was possible to order the chassis separately and later choose the body constructor of one’s preference.

The 57 is equipped by an 8-cylinder in-line engine of 3300 cc. with fixed heads integrated into the engine block. The engine block is based on a scheme that became typical for the last generation of Bugatti engines. With its fixed heads and double camshaft it is in some details similar to that of the model 50, but it has 6 main bearings. The cylinder barrels are practically subdivided in pairs of two along the block and there is a main bearing in the space between each couple. The last two bearings are at the rear, very close to each other.
The block of fixed heads offers many advantages but its maintenance is difficult.
One of the most delicate and complex tasks is for example the recalibration of the cylinders or better the adjustment of the cylinder barrels.

The 57 has a valve gear with a double over-head camshaft and 2 valves per cylinder. The control of camshafts consists of a train of straight-cut gears placed in the rear part of the engine next to the flywheel and the clutch. The gearbox is directly connected to the engine block and not joint with the differential gear. It was the first use of such solution in a Bugatti car.

The choice to place the valve train in the rear part of the block near the flywheel helps to reduce the effects of the drive shaft’s torsion on the valve gear itself. But it causes a further complication, as one more main bearing must be added between the first straight-cut gear of the valve train and the engine flywheel that naturally requires an appropriate support. That is why there are two main bearings so close to each other.

Furthermore, the valve gear train of the 57 presents a solution that was used for some period also by the other car designers of this era. Its intermediate straight-cut gear was not made of metal but of synthetic fibre. This element made it possible to significantly reduce the general noise level at the cost of reduction of reliability. Its life was indeed limited to about 30.000 miles (less then 50.000 km) and the fact that it didn’t warn you by any suspicious sounds until the very moment it got broken was surely another disadvantage. If this straight-cut gear broke up while the engine was running, the consequences as you may imagine were disastrous particularly because of the fact the engine valves were arranged in an inclusive angle of 96°. At the moment of failure, the valve gear train stopped and the valves that remained open then inevitably crashed against the pistons. While the maintenance was expensive, to fix such damage posed an enormous expense. But it is needless to say that the luxury of owning and maintaining a Bugatti was always reserved to a very few rich.