Fiat of Turin Reply

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[Last month’s article “Two Fiat ‘Firsts’ and a Fiat Failure” has aroused much interest, as this month’s Vintage Postbag (pages 1334 and 1336) confirms.
Fiat’s Centro Storico has done some useful research on the subjects raised by this article, a translation of which we publish herewith. It is unusual for manufacturers to take so much interest in history and encouraging that Fiat has done so. It now seems that Fiat’s two “firsts”—first supercharged car to win a race, first supercharged car to win a GP, stand, apart from anything Chadwick may have done in America and about which I remain unconvinced.—Ed.]

Nineteen Twenty-Three was the crucial year for the Fiat racing department, during which they developed supercharger installations and applied them to the firm’s racing cars. They had in fact already been working on the problems during the previous year, but it was in 1923 that supercharged Fiats first appeared on the circuits in open competition with rival machinery. Two models were raced, for in addition to the 805/405 (straight-eight 2-litre GP cars) there was the little 803/403 1½-litre. The latter car startled the pundits in two races—although the results were different in each case—the Voiturette GP at Brescia on June 29th and the Brooklands 200 Miles Race on October 13th.

Reporting the previous day’s race, the magazine Motori Aero Cicli e Sports for June 30th wrote: “The little Fiats which won at Brescia were similar to last year’s racing voiturettes, with four-cylinder o.h.v. engines of 1½-litres capacity: the same remarkable little engine which won the (Voiturette) GP at Monza and this year carried all before it at the Monte Carlo meeting. A number of modifications to it have been made, however, the most important being a turbo-compressor to provide forced induction. By means of this excellent device several extra b.h.p. have been gained, so that today the output of the little Fiat SS probably exceeds 80 b.h.p., or roughly 50 b.h.p. per litre, which is quite astonishing.” Nothing, alas, about the blowers themselves is to be found in that or any other press report. For the details we have to look elsewhere.

Such original drawings as survive indicate that two distinct types of supercharger were designed and produced for the Type 403 engine of 1923, known respectively as the “B” and the “D”, and differing fundamentally from one another.

The Type “B”, or “Wittig” as it was sometimes called, was described as a “compressor or induction-blower employing a drum with movable pallets”. This in fact meant a vane supercharger, or rotary blower in which the shaft carrying the drum and sliding vanes were mounted eccentrically in the housing. This blower formed the subject of a Fiat patent dated June 19th, 1923. Two further patents followed shortly (June 20th and August 5th), and were concerned with improving the co-efficient of friction between the vanes and the sides of the housing. In the August patent the sliding system was abolished, and the vanes were moved in and out in respect of their drum by means of a mechanical linkage.

From a purely historical point of view it should here be mentioned that the issue of Auto Italiana for January 10th, 1924, contained a note by Ing. G. Verdoja drawing attention to the fact that both the methods of driving the vanes which Fiat had just patented were based on the ingenious pumps devised by Captain Agostino Ramelli di Mosanzana dal Palte della Tresia, engineer to His Most Christian Majesty the King of France and Poland, in or before the year 1588.

The alternative “D” type of blower was what the British call a Roots, in which a housing contains two rotating paddles offset by 93 deg. in relation to one another. The Roots blower enabled mixture to be delivered to the cylinders at a considerably higher mean pressure than the 10-11 atmospheres (sic) attained by the “B” class of instrument. The new system, patented by Fiat on July 25th, 1923, included also a cooling system by which the compressed gases could be reduced to their original temperature so that on entering the cylinders they could undergo the further compression provided by Herr Otto’s well-known cycle without risk of detonation.

Once again Ing. Verdoja pointed out, in the same article, that the system commonly known as “Roots” bears a close resemblance to that invented by Payton in 1867 and named after him.

The “D” type Fiat compressors also underwent modifications: a patent of October 31st covered aero-engine applications, and there were two further patents (November and December of the same year) applying to motor cars.

Returning to the original drawings mentioned above, we find that these tie in very well chronologically with the patents. All the drawings relating to the “B” type of blower bear dates between February and April 1923, while those concerned with the “D” type are dated from July 1923. To recap: Type “B” was designed between February and April 1923 and patented in June of that year. Type “D” was designed in July 1923 and patented over the period July to December 1923. It is unquestionable, therefore, that the Wittig system had priority at Fiat, and was investigated, developed and applied to the model 803/403 racing car before the Roots. The same priority holds good for the model 805/405 GP cars which ran in the French Grand Prix at Tours.

The cars which ran in the French Grand Prix at Tours were indeed fitted with the “B” Wittig blower, and this, as was pointed out by Morasso, reporting on the race in Motori Aero Cicli e Sports for June 1923, resulted in the retirement of all three cars owing either to the “excessive temperature of the air compressed and thrust into the induction manifold” or, more probably, to an “unforeseen and irreparable breakage in the supercharger”. At Monza, therefore, the victorious Fiats raced with Roots blowers.

What, now, of the 1½-litre 803 cars raced at Brescia and Brooklands? What sort of superchargers were used respectively by Cagno in Italy and the teams of Salamano and Campbell in England? Contemporary reports are rather hazy on technical matters, especially concerning the Fiats. Both The Autocar and The Motor in their reports refer in general terms to the “turbo-compressor” or “supercharger” without going into technical detail. Even on the subject of the troubles which led to the Fiats’ retirement details are lacking, although it is clear that the blowers were to blame. However, from the documentary evidence already cited we can reasonably assert the following:

June 29th.—Voiturette GP, Brescia: 1st, Fiat 803/403 (Alessandro Cagno). “B”-type Wittig supercharger.
July 2nd.—French GP, Tours: Three cars entered (Bordino, Giaccone and Salamano). All three retired. “B” or Wittig blowers.
September 9th.—GP of Europe and Italy at Monza: 1st, Fiat 805/405 (Carlo Salamano). “D” or Roots blower.
October 13th.—JCC 200 Miles Race, Brooklands: Two cars (Salamano and Malcolm Campbell), both retired. “D” (Roots) blowers.

Why, it may be asked, was the initial success of the “B” or Wittig blower at Brescia followed by debacle in the ACF Grand Prix at Tours? Probably because in the light-car event the supercharger was required to run little more than 300 miles, while at Tours the blowers were far more highly tried, having to cope with a larger, more powerful engine, and a race that was 500 miles long. It seems likely that, with Tours in mind and another 500-mile race in prospect (the Italian GP at Monza), the Fiat engineers decided to re-think the whole installation and go over to a Roots—the “D” blower.

If this was so, it was a fortunate decision. Monza was too important for Fiat to risk another defeat on the scale of Tours; and in little more than two months the factory was ready with the new type of blower.

At Brooklands things went once more awry, and for reasons which are largely inexplicable. Without question the Fiats were the fastest cars on the track and the most advanced; their drivers were highly capable and experienced men. This time, however, the Roots or “D” type blower was blamed for the Fiat failure. During 1923 both the systems adopted successively by Fiat could point to one victory—and one no less resounding disaster.

After delving into contemporary documents with the results outlined above, members of the Centro Storico Fiat, or Archives Department, went along to see Commendatore Cagno, one of the drivers involved. On October 14th of the present year, 1969, the Commendatore, whose memory and enthusiasm are undimmed, agreed to cast his mind back 46 years, to the 1923 season when he was acting both as racing manager to Fiat and as a member of the works team.

On Comm. Cagno’s evidence there is no doubt whatever that the 803/403 Fiat engine was originally designed without supercharger. Later, in time for the race at Brescia, it was fitted with a blower of the Wittig pattern, but although this brought victory in the race for Cagno, it also brought difficulties to the engineering department, and Cagno confirms that it was decided to discard the Wittig in favour of another type, of which, unfortunately, he cannot remember the details or the name. (This was probably the Roots.)

On the subject of drivers for Brooklands, Comm. Cagno remarked the choice was made largely on what may be called “diplomatic” grounds. Clearly Salamano, fresh from his victory in the European and Italian GP, was the best-known driver in the Fiat team, and was an obvious choice as “ambassador” in a foreign land. Equally cogent were the reasons for briefing Malcolm Campbell. His knowledge of Brooklands was probably unequalled, he was always “news”, and the fact that one of the exciting Italian cars was to be handled by an-English driver would ensure maximum publicity for the marque.

The 200 Miles Race brought luck to neither of the drivers. Commendatore Cagno, although remembering the occasion well enough, is unable to recall the reason or reasons underlying the retirement of the two 803s. Some details perhaps will remain always obscure, but it is interesting to receive first-hand testimony as to the broad facts by one of the actual participants, and confirmation from the same source of the conclusions already reached from study of the history books and blueprints.