The new Bugatti Grand Prix car made its first public appearance during practice for the French Grand Prix, as had been promised earlier in the year, and though it did not give a very impressive performance, at least it appeared and started in the race as promised.
The chassis is of space-frame type, built of small-diameter tubing and is roughly rectangular box-shape in layout, being very large in width, as the 8-cylinder in-line engine is mounted transversely. This straight-eight engine has a bore and stroke of 75 by 68.8 mm, giving a capacity of 2,430 cc, and runs to 9,000 rpm, has twin overhead camshafts driven from a train of gears from the centre of the crankshaft, and in outward appearance looks very much like the old 2.9-litre Monoposto Alfa-Romeo engine. The transverse mounting is such that the inlet ports face forwards and the exhaust ports rearwards, and four double-choke Weber carburetters are used, while the eight exhaust pipes are grouped in fours, each group converging into a large expansion box with a single tail pipe sticking out through the tail of the car. The air-intakes of the carburetters are fitted into an aluminium box which is just behind the driving seat and air is fed into this box from two large flexible pipes, one along each side of the cockpit, which join on to an air scoop in front of the windscreen. The radiator is in the nose of the car and the water is carried from the engine to the radiator and back again by means of the frame tubes. From each set of four cylinders a water pipe runs along the cylinder head and joins the chassis tube by means of a simple two-bolt flange. There are two sparking plugs per cylinder and these are fired from magnetos mounted in front of the engine below the carburetters.
Behind the engine itself is an aluminium housing containing spur gears driven from the centre of the crankshaft and on the right hand side of this is the five-speed gearbox, so that the drive leaves the centre of the crankshaft, passes through the spur gears and into the gearbox, out of the same end of the gearbox and still by spur gears to the differential. Then it is taken by double universally-jointed half-shafts to the rear wheels. The whole engine/gearbox/final-drive unit is bolted together and attached rigidly to the chassis frame. The gearbox is a true five-speed, in which all gears can be used when in motion, and is of Porsche design, using Porsche patent synchronising rings, with constant-mesh pinions.
The cockpit has high sides, but is fairly capacious, and the car is fitted with a traditional Bugatti four-spoke, steering wheel having the revered EB insignia in the centre, while the same trade mark is stamped on the pedals. The gear-lever operates in an open gate and is on the right-hand side of the cockpit, while the accelerator pedal is centrally mounted. The wheelbase of this car is very short and on each side of the cockpit is a fuel tank, so that the car has a very bulbous appearance.
Rear suspension is de Dion layout of very simple conception, with the de Dion tube behind the axle centre line, located on a central sliding trunnion and positioned fore and aft by double radius-rods. Pivoted on the frame transversely above the axle assembly are two large rocker arms, one on each side of the car, and the outer ends are coupled by vertical links to the ends of the de Dion tube. The inner ends are coupled to very long rods which compress coil-springs, these springs being mounted on the opposite bottom side tube of the chassis frame. The principle of this system being that it transfers the load of a rising wheel through the chassis frame, which acts on the linkage to the opposite wheel and consequently tends to push that wheel down on to the road with an equal force to that which is pushing the other wheel upwards. A similar geometrical layout is used at the front, the wheels being mounted on the end of a tubular beam axle which is located by a central sliding guide and double radius-rods at each end. The brakes are normal two-shoe drum type, of very large diameter, though disc brakes are under construction for the future. Telescopic shock-absorbers are used on all four wheels.
At the time of the French Grand Prix, on July 1st, only two cars had been completed and the second one had a slightly longer chassis and wheelbase, as the original car had a bad habit of weaving badly. However, during practice it was found that the longer car was little better, and for the actual race the first car was used. Its performance on its first outing was such that it was about the equal of the eight cylinder Gordini, and it was interesting that both French Formula 1 Grand Prix cars use eight-cylinder engines, a layout popular with French factories since 1919, while the Gordini has all four wheels independently sprung and the Bugatti has rigid axles back and front.
As yet the Bugatti 251 is much too new to form any serious opinion, but the factory are building eight cars altogether and intend to make a serious attempt at Grand Prix racing. Bearing in mind the very small size of the Bugatti works at Molsheim, it would be foolish to expect too much from such a revolutionary approach to Grand Prix car design.—DSJ.
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