Miguel Sánchez
In the last Grand Prix History From Monaco we could see a Bugatti Type 37A dealing with an Amilcar C6. A priori, this is just another among the many scenes starring in that career by various models of the twenties. However, reviewing the mechanics of these two nearly century-old racing cars highlights an obvious connection. The use of the Roots compressor. A mechanism patented in 1860 to serve as an air pump in blast furnaces, thus improving combustion in them. However, its properties did not go unnoticed by motorsports. Of course, exactly four decades had to pass before Daimler applied it for the first time to improve the performance of a combustion engine.
In this way, compressing the air focused on the cylinder improved combustion by increasing the oxygen concentration. A principle by which the mixture formed with gasoline was enriched. Promoting a considerable increase in power without the need to increase the displacement of the engine. Rather the complete opposite. And it is that, thanks to the Roots compressors it was possible to reach a considerable number of horsepower even using small and light mechanics. Thus, together with the improvements made by Vittorio Jano in his Alfa Romeos, the XNUMXs buried the endless increases in displacement. Seen so far as the only way to gain speed.
With all this, in those years numerous racing models appeared where more efficient mechanics combined with reduced weight to deliver better results. A way of working in which the Bugatti Type 37A was an exceptional benchmark. Born in 1928, this model dispensed with the eight-cylinder engine of the Type 35 - from which everything else was derived - to mount a concise 1.5-liter four-cylinder. Of course, with the help of a Roots compressor, the power rose to 90CV.
Granted, less than what is offered by the most performance versions of the Type 35. But, nevertheless, extremely effective on the track since the Type 37A enjoyed a much lower weight than that presented by the Bugatti with eight cylinders. And it is that, after all, the important thing is not the power itself. But the relationship that it has with the weight it has to move. An approach that also guided the design of the Amilcar C1926 in 6. Possibly the most ingenious and celebrated racing model in the short but intense history of the French manufacturer, surprising for its successful weight / power ratio.
FROM CYCLECAR TO GP
After the First World War the world of automobile racing experienced a real explosion. Held in various European countries with categories for vehicles of all kinds and conditions, the so-called cyclecar stood out. Small and modest models from companies like Bedelia. With the chassis cut just at the height of the rear axle, more than bare wheels and wooden bodies covered with sheet metal. That is, vehicles that are hard to call full-fledged cars. Although, after all, they guaranteed great fun on four wheels despite their small displacement and low power engines.
Thus, when Amilcar was founded in 1921, it began to present models without a differential. With a brake only on the rear wheels, thus stopping the only 18CV delivered by its four-liter engine block and 904 cubic centimeters. Nevertheless, their nervous and playful behavior makes the Amilcar a very desirable little sports car. Even more so according to these they are becoming common on the starting grid of races as symbolic as the first edition of the 24 Hours of Le Mans.
What's more, with its relatively accessible price, the Amilcars are putting sportsmanship within the reach of the middle classes together with the also brief but effective Salmson. All this to gain a well-deserved fame among the young or female audience. Something that was very present on the morning of April 15, 1931. When one of the most reproduced snapshots to illustrate the proclamation of the Second Republic during the afternoon of the previous day was that of a young woman from Barcelona driving an Amilcar while carrying a huge tricolor flag. With all this, these French vehicles were seen at the time as a kind of Bugatti in small. Something that did not prevent the brand from wanting to build a model that, without diminutives, could be measured face to face in the GPs with its improvised older brothers.
AMILCAR C6, A SPORTS CAR WITH ALL OF THE LAW
By the mid-160s, the Amilcars had grown thanks to models like the CGS. In fact, its engine block already reached a displacement that exceeded one liter, reaching top speeds of up to XNUMX km/hour. An increase in benefits that, although considerable, It was still far from what was given by the Bugatti Type 35. However, for 1926 the GP organization limited the displacement to 1.5 litres. In addition, the rapid expansion of the Roots compressor - reaching its peak with the 1929 Bentley Blower - made it possible to squeeze almost an extra third of power out of the engines.
At this point, it was the right time to launch a true GP model. The Hamilcar C6. Thus, they developed a 1.1-liter in-line six-cylinder engine capable of delivering up to 83CV at 6.000 rpm thanks to the action of a Roots compressor driven by the crankshaft. All of it about a simple and light chassis with leaf spring suspensions, being able to reach a maximum of 169 km/hour. Under these parameters, the Amilcar C6 appeared as a light and mechanically very efficient car. Using the advantages of the compressor to deliver a good dose of power without the need to increase weight or consumption.
Personally, this type of design that the Amilcar C6 boasts reminds us of the way things are done at Lotus. And we love that. After all, the fact that such models came to light in the XNUMXs was of essential importance. Helping to define a radical turn in the conception of motor sports. However, as the XNUMXs experienced a boom in the financial bubble, the public demanded more high-performance and exclusive models than those offered by Amilcar.
In this way, paradoxically, there was no longer any room for these light and rational sports cars with the new middle classes as their objective. With all this, in 1929 Amilcar received a severe blow when he lost the factory in the midst of a sales crisis that he tried to refute by giving a new focus to his activity. Thus, During the XNUMXs, he put aside those small sports cars to enter the field of play of generalist brands such as Citroën or Renault.. A very different story from that of the Amilcar C6. Undoubtedly one of the most interesting racing cars of the twenties.
Photographs: Bonhams / Unai Ona
