The 1931 Grand Prix season was a watershed year, with the advent of the AIACR European Championship. After several years of Grand Prix racing in the doldrums with little technical development, 1931 saw new models come from all three main manufacturers: Bugatti, Maserati and Alfa Romeo.
The AIACR regulations were to Formula Libre (open formula) rules for the cars, but the race-format chosen was to run the Grands Prix over a marathon ten hours each with two drivers per car. The pair had to be the same for all three races otherwise only the lead driver would score points. The championship was won by Ferdinando Minoia, driving for the Alfa Corse works team. He was tied on points with his team-mate Giuseppe Campari after the three races. Despite not having won any of the races, his consistency gave him the tiebreaker by covering a greater distance across the combined 30 hours of racing. However, the endurance format of the series was exhausting and unpopular with the drivers, and became processional and boring for the spectators and would not be repeated.
In the other major races of the season, the new Bugatti Type 51 won its first event, at Tunis, and dominated the French circuits in the early half of the season. The Italian Championship regularly drew the best drivers and gave close racing between Alfa Romeo, Bugatti and Maserati. At the end of the season, the championship was awarded to Alfa Romeo driver Campari, on a tie-breaker countback. With both major titles in their cabinet, Alfa Romeo finished the season strongly.
European Championship Grands Prix Date Name Circuit RaceRegulations Weather RaceDistance Winner'sTime Winning driver Winningconstructor Fastestlap Report A24 May IX Italian Grand PrixVII European Grand Prix Monza A-circuit Georgano 1971, p.118 AIACR very hot1550 km(winner)10 hours Giuseppe Campari Alfa Romeo 8C 2300 Giuseppe Campari Alfa RomeoReport Tazio Nuvolari B21 Jun XXV Grand Prix de l’ACFMontlhéry Georgano 1971, p.119-20 AIACRhot1259 km(winner)10 hours Louis ChironBugatti Type 51Luigi Fagioli MaseratiReport Achille Varzi C12 Jul III Belgian Grand Prix Spa-Francorchamps Georgano 1971, p.143-4 AIACRsunny1320 km(winner)10 hours William Grover-Williams("W. Williams")Bugatti Type 51Louis Chiron Bugatti Report Caberto Conelli
Other Grand Épreuves Date Name Circuit RaceRegulations Weather RaceDistance Winner'sTime Winning driver Winningconstructor Fastestlap Report 30 May XIX International 500 Mile Sweepstakes Indianapolis AAA cloudy 500 miles 5h 10m Louis Schneider Stevens-Miller not recorded Report 7 19 Jul V Großer Preis von Deutschland Nürburgring Georgano 1971, p.123 Formula LibreVoiturette heavy rain 502 km 4h 38m Rudolf Caracciola Mercedes-Benz SSKL Achille VarziBugatti Report 22 Aug British Grand Prix Brooklands not held 11 Sep Spanish Grand Prix Lasarte cancelled A grey background indicates the race was not held this year. Sources: Rendall 1993, p.362
Major Races Multiple classes are mentioned when they were divided and run to different race lengths. Date Name Circuit RaceRegulations Weather RaceDistance Winner'sTime Winning driver Winningconstructor Report 22 Feb Sveriges Vinter Grand Prix Lake Rämen Formula Libre cloudy then sunny 385 km 5h 29m Karl Ebb Auburn Special Report 15 Mar Gran Premio di Tripoli Tagiura cancelled 23 Mar IV Australian Grand Prix Phillip Island 2000cc maximum engine capacity Fine & mild 200 miles 2h 55m Carl Junker Bugatti Type 39 Report 1 29 Mar III Grand Prix de Tunisie Carthage Formula LibreVoiturette sunny 470 km 3h 24m Achille Varzi Bugatti Type 51 Report 6 Apr II Circuit d'Ésterel Plage L’Éstrel beach,Saint-Raphaël Formula LibreVoiturette ? 66 km 48m Philippe Étancelin Bugatti Type 35C Report Hungarian Grand Prix cancelled 2 19 Apr III Grand Prix de Monaco Monte Carlo Formula Libre sunny 320 km*(315 km) 3h 39m Louis Chiron Bugatti Type 51 Report 3 26 Apr VIII Circuito di Alessandria(Gran Premio Bordino) Alessandria Formula Libre cloudy 280 km 2h 06m Achille Varzi Bugatti Type 51 Report 410 May XXII Targa Florio Grande Madonie Georgano 1971, p.145-6 Targa Florio heavy rain 580 km 9h 00m Tazio Nuvolari Alfa Romeo 8C 2300 Report VII Grand Prix de Picardie Péronne Formula LibreVoiturette ? 210 km(winner) 2 hours "Ivernel" Bugatti Type 35B Report 17 May I Casablanca Grand PrixV Moroccan Grand Prix Anfa Circuit Formula LibreVoiturette sunny 370 km 2h 42m Count Stanisław Czaykowski Bugatti Type 51 Report 24 May VI Grand Prix des Frontières Chimay Formula LibreVoiturette rainthen cloudy 160 km 1h 26m Arthur Legat Bugatti Type 37A Report 57 Jun VII Premio Reale di Roma Littorio Formula Libre,heats ? 240 km 1h 35m Ernesto Maserati Maserati Tipo V4 Report I Grand Prix de Genève Meyrin Formula Libre,heatsVoiturette sunny 250 km 1h 26m Marcel Lehoux Bugatti Type 51 Report V Eifelrennen Südschleife,Nürburgring Formula Libre cloudy, thenshowers 310 km 2h 51m Rudolf Caracciola Mercedes-Benz SSKL Report II Grand Prix Miasta Lwowa(Großer Preis von Lemberg) Lviv Georgano 1971, p.109-110 Formula Libre rain 150 km 1h 57m Hans Stuck Mercedes-Benz SSK Report 14 Jun Vienna Grand Prix cancelled 65 Jul VII Grand Prix de la Marne Reims-Gueux Formula LibreVoiturette sunny 400 km 2h 48m Marcel Lehoux Bugatti Type 51 Report Grand Prix du Vaucluse Circuit de RéalpanierAvignon Formula LibreVoiturette ? 100 km 55m Frédéric Toselli Bugatti Type 37A Report 26 Jul III Dieppe Grand Prix Dieppe Formula LibreVoiturette windythen rain 480 km 4 hours Philippe Étancelin Alfa Romeo 8C 2300 Report 82 Aug V Coppa Ciano Montenero Formula LibreVoiturette hot 200 km 2h 24m Tazio Nuvolari Alfa Romeo Report I Internationales Avus-rennen AVUS Georgano 1971, p.65 Formula LibreVoiturette hot 300 km 1h 35m Rudolf Caracciola Mercedes-Benz SSKL Report II Circuit du Dauphiné Grenoble Formula LibreVoiturette ? 240 km 2h 02m Philippe Étancelin Alfa Romeo 8C 2300 Report 916 Aug VII Coppa Acerbo Pescara Georgano 1971, p.129-30 Formula LibreVoiturette hot 300 km 2h 20m Giuseppe Campari Alfa Romeo Tipo A Report VII Grand Prix du Comminges Saint-Gaudens Formula LibreVoiturette sunny 400 km 2h 49m Philippe Étancelin Alfa Romeo 8C 2300 Report 106 Sep IV Gran Premio di Monza Monza C-circuit Formula Libre,heats sunny 240 km 1h 33m Luigi Fagioli Maserati 8C-2800 Report VII Gran Premio delle Vetturette Monza C-circuit Voiturette sunny 140 km 1h 01m / José Scaron Amilcar MCO Report 13 Sep VII Grand Prix de la Baule La Baule beach Formula Libre sunny 150 km 1h 03m William Grover-Williams Bugatti Type 51 Report 19 Sep V Circuito di Cremona Cremona cancelled 1127 Sep II Masaryk Circuit Masaryk-Ring,Brno Formula LibreVoiturette cold 500 km 4h 12m Louis Chiron Bugatti Type 51 Report Grand Prix de Brignoles Brignoles Formula Libre sunny 44 km 1h 03m William Grover-Williams Bugatti Type 51 Report Note: *Race mistakenly flagged by officials after only 99 laps, not the full 100 as scheduled
Regulations and Technical
In October 1930, the CSI regulatory body of the AIACR met to draft up rules for a new championship. The racing bodies of Belgium, France, Italy and Spain would hold events lasting ten hours, with the results merged as a single race- the International Grand Prix. Each body would contribute 150000 francs, and the driver covering the farthest distance over the four races would collect half a million francs. However, that idea was deemed impractical and instead the races should be discrete, individual events. As all the races took place in Europe it was renamed the European Automobile Championship.
The media soon spotted major issues with the proposal – after the abortive Manufacturer's Championship, just a few years earlier. If the field was whittled down after three or four hours, what was to be gained if only a half-dozen cars raced for the latter half of the race? They protested that it would bore the spectators, and drive them away well before the end of the races. However, the CSI was not swayed and confirmed the format in March. The Italian GP was moved from its traditional September to May to be able to run in good daylight and the Spanish GP was dropped from the list. Now the overall winner would receive 150000 francs. The two drivers had to be paired together for all three races and would only score points in the car they had been nominated for. In case of a tie, the driver(s) who had covered the greatest total distance would win the tie-break. The cars would otherwise not be limited, running to Formula Libre. A proposal to run a gasoline/benzole mixture was discarded as Italy had no benzole.
Technical Innovation After a lethargic period of years with only incremental development, 1931 saw a good range of new models and innovation from all three main manufacturers. At his son's insistence, Ettore Bugatti had swapped the Millers of American Leon Duray for a trio of Type 43 sports cars in 1929. Cimarosti 1997, p.84 Venables 2009, p.62 Examination of the advanced engineering of the Miller engine led to the developed of the Bugatti Type 51. Essentially the same as the Type 35B, still using two valves per cylinder and a single carburettor, it was now fitted with twin overhead camshafts and put out 180 bhp. At the fast Monza Grand Prix, Bugatti also entered the new Type 54 (purportedly produced in only 13 days Venables 2009, p.63), with the 5-litre engine of the Type 50 sports car. But despite developing an enormous 300 bhp, raw power on paper was no key to success. Front-heavy, it handled poorly and was terrible on its tyres.
Maserati had led the way forward the previous year with the 8C-2500 engine in the Tipo 26M. The brothers further developed the engine, boring it out to 2.8-litres, also introduced at the Monza race. The team continued to run that model through this season, as well as the mighty, twin-engined V4 on the open fast circuits. Voiturette racing was increasing in popularity again, with over a dozen races scheduled for the season. After his success the previous year, Alfieri felt encouraged to develop the 1.5-litre 26C. The new 1.1-litre twin-cam 4-cylinder model – either the 4CS sports car or 4CM (monoposto) single-seater - would soon dominate the small classes, and earn good money for Maserati in both prizemoney and privateer sales. Ludvigsen 2008, p.81
With the final retirement of the Alfa Romeo P2 from front-line racing, Vittorio Jano produced two quite different models for the new Championship. The 8C 2300 was a development from the 6C 1750 sports car. Jano put a pair of 4-cylinder engines back-to-back with a common gear-train linking the two camshafts. Being centrally mounted it minimised the engine torque and vibration. It came in two variants – the long-wheelbase version was the sports car, while the nimbler, short-wheelbase model entered Grand Prix races. Ludvigsen 2008, p.72 Monkhouse 1953, p.11 To take on the big-engined Mercedes, Jano built the Tipo A. Taking two complete engines of the 6C 1750, and mounting them side by side. The mirror-image arrangement improved traction because of the equal and opposite torque of the engines. Ludvigsen 2008, p.59 Alfa's (and Europe's) first monoposto, the driver sat centrally, over the two driveshafts in a deep, streamlined cockpit. Unlike the twin-engined Bugatti and Maserati, each engine of the Tipo A kept its own power-train with crankcase and driveshaft. Cimarosti 1997, p.90 A single gear lever controlled both gearboxes with an overrunning clutch. Only four were built. Cimarosti 1997, p.88 Georgano 1971, p.337