It is well-known that Ettore Bugatti, as well as being an eccentric in his lifestyle, was eccentric over the design of his cars, resisting independent front suspension, twin-overhead-camshaft engines and hydraulic brakes far longer than others. He was also against supercharging for a long time, until forced to adopt it when outclassed in races.
Forcing the mixture into the cylinders with a pump, nowadays usually in the form of turbocharging, with only an occasional return to mechanical supercharging, is again in vogue. So let us see what steps Bugatti took to publicise supercharging after putting blowers on his racing and sports-car engines.
Having produced blown versions of the famous straight-eight Type 35 GP and four-cylinder Type 37 racing cars, Bugatti used an almost similar engine to the blown Type 35B for his exciting Type 43 four-seater Grand Sport model. To convince potential customers this was a Good Thing he arranged, late in 1927, for the celebrated French motoring journalist WF Bradley to test this Bugatti both supercharged, as sold, and non-supercharged.
Ettore was at the time claiming that supercharging did not necessarily mean high fuel consumption, quoting 43 mpg from his blown 11/2-litre model when averaging 45 mph over long road runs. He provided a Type 43 for Bradley in its normal Roots-supercharged form, and immediately afterwards let him try this same car after the supercharger had been removed and two Solex carburettors substituted. What transpired was that, on a 40km run , the blown Type 43 gave 17.43 mpg and in unblown form only 11.94 mpg. Rather a surprising result, you might think, especially as in blown guise Bradley reported the Bugatti to be faster, more accelerative and more flexible. In fact, the journalist was only an observer, the Type 43 being driven by racing driver M Costantini. Petrol thirst was checked by using a tall tank on the back seat (where it replaced the normal seat cushions) possessing a glass sight-gauge marked off in litres.
The first run commenced from the factory in Molsheim, and went over narrow, winding, rather hilly lanes at the foot of the Vosges. The average speed was 46 mph for the 24.85 miles, so 17.45 mpg was notably good. Having satisfied himself that fuel consumption was improved by supercharging, Bradley then had Costantini do acceleration tests from a standing-start, to 3000rpm and 4000rpm., This was considered more accurate than using speedometer readings; if wheelspin away from rest was ignored, these equalled speeds at those rev-readings of 63 and 83.6 mph. Type 43 owners may be interested to learn that the times recorded were 30.7 sec and fractionally less than 41.4 sec respectively, averaged over a number of runs — it is interesting that even the experienced racing driver improved his times progressively! The Bugatti weighed 21 cwt 68 lb.
To show that supercharging did not bring with it rough low-speed running, 200 metres were covered in top gear at an average of 6.13mph for three timed runs. Again, Costantini became progressively more proficient at this, improving by almost minus five mph between his first and last run, which at least suggests he had not practised beforehand. The Bugatti was then taken back to the factory and two carburettors on a normal inlet pipe fitted. The mixture was weak, so far more gear-changes were needed to maintain the same average speed as before over the 40km route; in spite of this weak setting, in supercharged form the engine gave the better petrol consumption by as much as 5.49 mpg. Then, as would be expected, the unblown car was inferior in acceleration, taking on average 10.3 sec longer to reach 3000 rpm, and more than 25 sec longer to 4000 rpm, the gain for the blown engine being 23 sec to 4000 rpm on its quickest runs.
The slow-speed runs were then done with the twin-carburettor engine, a freak jerky performance anyway; the unblown engine throttled down to a slower pace on two runs, but was beaten to the crawl by the supercharged engine on its best run.
The apparent superiority of the supercharged Bugatti was enhanced by Bradley saying that in blown guise the fuel mixture was rich, spoiling the slow-running, whereas for the unblown runs the carburettors were set up as for the Targa Florio (for the Type 35T GP cars, presumably) and were too weak in the cold of an Alsace December. The unblown engine had the lower compression ratio of the blown power-unit (4.5:1), which could have reduced its efficiency.
To round things off, the rich mixture of the supercharged Type 43 was later to some extent corrected, when fuel consumption improved fractionally and the acceleration time improved to 34 sec from 0-4000 rpm (Costantini did his best of five runs first and last, so there seems to have been no deception), and a standing start kilometre was covered in 25 sec (probably an error, as this would be 13.21 mph faster than Kaye Don’s class record with a 35B). Road conditions were said to have prevented the car from doing a timed kilometre, but the speedometer read 112 mph more than once, Costantini going up to 5500 rpm, whereas with the unblown epgine he could not get more than 4500 rpm.
The supercharger blew at 400g/sq cm. Bradley remarked that it could have been rendered silent had the blower-drive been by chain instead of by gears (the charm of the Type 43, though, is enhanced by the noises it makes!), and observed that supercharging improved turbulence within the cylinders. Was this Ettore’s answer at that time to those advocating twin-cam heads? WB
Our Fragments on the Reynard (Motor Sport, June 1987) has produced an interesting letter from Mr JJ Hall of St Albans, quoting an advertisement for a Reynard Special for sale by Guy Griffiths back in April 1935, the asking price being £75. The car was described as “a 1500cc 14hp competition two-seater, in cream, with outside exhaust-pipes, the actual car used at Donington and Phoenix Park”, but with full touring equipment. It had a Ricardo head, which does not seem to go with a Meadows engine, so we wonder if this car had really any connection with the Reynard we described, although the large brakes and inclined radiator would correspond. Does anyone recall this racing Reynard? Our correspondent points out that the Reynard we illustrated was registered not in Oxfordshire but in London. WB
VSCC Shelsley Walsh
Much history has been established at Shelsley Walsh since 1905, and another little bit was added on June 4 at the VSCC hill-climb. Entries were down, but the event was highly enjoyable in the “Wimbledon” sunshine. What a pity, though, that the racing cars now have to wear silencers — these standardised “cans” look out of place, especially on ERAs and protruding from the “Tiger”.
The last-named Sunbeam had recovered from its Silverstone contretemps, and Bob Roberts had it going well. The Becke nearly asphyxiated its driver, according to commentator Hull, Felton had 300 bhp to propel the monoposto Alfa up the hill and Webster took the Spikims Bantam (blown Singer 9) off the line quietly, whereas the offside rear wheel of Threlfall’s Ford Riley (no, not that sort!) Special spun merrily. Danaher in the 4CM Maserati was very neat at this starting-off business . . . Spollon got ERA R8C away skilfully, eschewing driving gloves; wheelspin was excessive from the shining Giron-Alvis; and Summers’ 6CM Maserati had a rasping exhaust note.
Edwardians were out in force — the 1908 GP Panhard getting away comparatively slowly but clocking 53 mph through the speed-trap, the Gordon Bennett Star sounding every inch the veteran it is, the 1913 Th-Schneider revving like a later car, and Neve for once stalling the engine of the TT Humber. Tarring blipped the big Napier at the off, and Hickling’s 1917 Dodge loudly squealed a tyre. Enticknap and Caroline drove Super Aero Morgans (a single rear wheel no apparent disadvantage) and Talbot BGH 23 was outagain. WB