In examining Fiat factory drawings of superchargers used on the 805/405 cars I came up with a hypothesis which doesn’t seem to be specifically disproven by any material provided by Fiat or by your researchers. The superchargers of Wittig type made for the two sizes of cars initially were identical in diameter but different in length, to suit the different engine displacements. After the difficulties at Tours with the blower, we know that Fiat initiated what we would call today a crash programme to build new blowers for the cars for Monza. These Roots units were of course an improvement. But unless some special gear were used, the same Roots unit could not also be applied to the smaller type 803/403 racing car. A smaller version of the basic supercharger would have had to be made. What I would suggest—and would seem not to be specifically contradicted by Commendatore Cagno—is that Fiat decided not to go to the additional expense of making special Roots blowers for the four-cylinder car, and decided to risk running them in England with compressors of the original Wittig type, since it wasn’t likely to be dusty and dirty at Brooklands. Under such circumstances it’s likely Fiat would have said very little about the reason for retirement, especially if it involved the supercharger, which the outside world already knew was suspect after Tours.
I hope these views may be of interest to you and your readers.
K. LUDVIGSEN – New York.