I have no facts but my observations about and participation in racing activities would suggest that they kept wanting to go faster by making it lighter, so kept drilling holes until something cracked. I know on my old Formula Ford that whenever I took off something that looked just fine it would often come off in three pieces which had been held together by the bolt and washer.

They were fast cars in their day. The supercharger was connected though a clutch which could be activated by the driver by pushing the pedal down further, like a progressive linkage in a multiple carb setup. They were only allowed a certain number of seconds, like perhaps 15 of boost at one time. So it was sort of a passing button using 30s tech.

Pretty nice to look at too.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.