I respond to the letters from Peter Hull and D Ellis, who support the supercharged view of motor racing history. Peter Hull suggests that the unblown 3.6-litre pushrod Delahayes did not, as I had remarked, “seriously alarm” the blown 2.9 Alfas in the 1937 Mille Miglia; to which I would point out that at Rome the two Delahayes lay second and third behind Pintacuda’s 2.9, and that Italians brought up to believe that he who led at Rome would never lead at Brescia were indeed seriously alarmed.
In the 1938 Mille Miglia the V12 Delahayes were over-geared (a common failing among foreign entrants, whose lack of local knowledge was always a fearful disadvantage, equivalent to as much as an hour’s circuit time), while their entry had alarmed Alfa Romeo seriously enough for it to fit at least one of its blown 2.9s with a full race 3-litre engine from its current 308 Grand Prix car — something permissible under Mille Miglia rules (or lack of them) but nowhere else.
In 1938 Bugatti gave sportscar racing a miss, and by 1939 his unblown 3.3-litre 57S model “tanks” were ineligible for Le Mans because the 57S was no longer in production; it had been superseded by the long-chassis supercharged 57C, hence the construction of a new “tank” on that chassis for the 1939 race. It was led by Louis Gerard’s unblown 3-litre pushrod Delage for 21 hours before his co-driver Georges Monneret over-revved it, and the Bugatti won only after its entire undershield had been removed (a matter requiring instant disqualification under Le Mans rules) to cure mortal overheating problems; its average of 139.781 kph for a dry weather race was just 2.78 kph faster than that of its unblown sister in the 1937 race, which had been slowed by long periods of heavy overnight rain.
During the dreadfully wet 24-hour race at Spa in 1938, Gerard’s earlier 3-litre Delage was faster at all times than the blown 2.9 Alfas, which were several cwt heavier and had been detuned to run on the Belgian pump fuel which had destroyed one of their engines in the 1936 race. The Delage ran on Belgian petrol very well, and failed to win only because this time Monneret twice put it off the road, losing five laps in all.
Mr Ellis says that turbochargers have “moved engine efficiency into a new league”. Not so. The great period of forced induction advance in Grand Prix racing was 1937-39, at the end of which period the Germans had developed two-stage supercharging and were getting 160 bhp per litre — approximately three times what unblown car engines were then doing. The three-to-one ratio established at that time resulted in a 1½-litre blown, 4½-litre unblown Grand Prix formula being mooted for 1940, eventually to be introduced after the War; and if Mr Ellis was at Silverstone on that splendid fourteenth day of July 1951, he would have witnessed the Bastille of the supercharged 1½s finally falling to the muskets of the unblown 4½.
Since then there has been little movement in the relative efficiency of the two types of engine. If there had been unblown 4½s (instead of 3½s) running alongside the 1½ turbos last year, neither I nor Messrs Hull and Ellis need have any doubts about which would have won.
It is the way of a world ruled by the Law of Sod that after unreservedly praising Jaguar for resisting the turbocharger, the company should announce its defection the following week. Pity.
Anthony Blight, Callington, Cornwall