The forthcoming Amelia Island event by RM Auctions next month will feature the sale of one of the greatest prewar sports cars in the collector car market today. The vehicle in question is a rare 1930 Alfa Romeo 6C 1750 Gran Sport example, estimated to fetch between $1,100,000-$1,500,000.
Featuring a lightweight Zagato bodywork, the vehicle is fitted with a 85 bhp, 1,752 cc supercharged DOHC inline six-cylinder engine, four-speed manual gearbox, solid front and live rear axle with semi-elliptic leaf springs, and four-wheel drum brakes.
One of the largest changes introduced with the 4th series Gran Sport was a modified Roots-type supercharger that operated at engine speed and with larger rotors. With no step gear, it ran slower and therefore spun the opposite direction which relocated the carburetor from the left to the right side of the manifold.1
With its supercharger, the 1750 Gran Sport was an invincible race car, one with ample torque for its small chassis. The supercharger was a necessary ingredient that allowed the 1750 to be light, yet powerful, a characteristic that contributed to less driver fatigue and less stress on individual components. It was somewhat rare on sports cars of the period but was proven effective with the 1929 Super Sport. For the Gran Sport the engines main bearings also increased in size.1
In competition, the 6C-1750 was quite possibly the most successful car/chassis ever manufactured by Alfa Romeo. In addition to winning the 1929 Mille Miglia, twenty-five out of twenty-six supercharged 1750s completed the 1000 mile course. During the 1930 Mille Miglia, the 1750 would sweep the first four places in the race and would become known for an epic 6C-1750 duel between Nuvolari and Varzi. Nuvolari overtook Varzi in the pre-dawn with his 1750's headlights switched off and continued to win the race with a finishing time of 6 hours 18 minutes 59 seconds (averaging 62.78 mph) making the 6C-1750 the first car to ever complete the 1000 mile Mille Miglia Race averaging over 100 kph.
Other victories included the 1929 and 1930 24-Hours of Spa, 1930 Tourist Trophy, several World Speed Records (2000cc class) at Montlhery, France in 1931 (including 1000 kilometers @ 97.1 mph, 4000 Mile Record @ 93.97 mph and 48 Hour Record @ 94.4 mph) as well as winning numerous other Road Races, and Hillclimbs.
The current owner, a noted collector in his own right, has been absolutely pleased with the car’s rally abilities. For long distance driving, he has fitted a custom made sling to alleviate the leg fatigue caused by the centre throttle pedal and put the steering wheel into the second, more comfortable, driving position – neither of which has modified the car in any way. On the button and perfectly sorted, it is ready for a fourth Mille Miglia entry!
FRENCHTEXT
85 ch., 1.752 cm3, 6-cylindres en ligne à double arbre-à-came en tête et compresseur type Rootes, boîte 4-vitesses manuelle, essieux avant et arrière rigides avec ressorts à lames semi-elliptiques, freins à tambour aux quatre roues. Empattement: 2,740 mm (108")
