This page is dedicated to the memory of Pat Braden who died on August 25, 2002.
Pre-War Successes and Failures
By the mid-1930s, automotive engineers were able to produce engines
which developed more power than could be applied to the road. The fault
can be laid to a want of more sophisticated chassis and tires. On a classic
car such as the 6C1750 or an
8C2300 the duration of tire contact with
the road depended almost entirely on how supple the chassis was: it --
rather than the springs -- helped keep the tires in contact with the road.
The springs, which we modern types have come to expect to be the
supple member of the suspension, were made almost-rigid in the 1930s
to reduce body roll and improve the predictability of handling. The tires
of that period were skinny and relatively hard, offering very little
traction. Between 1935-1940, independent suspension improved
roadholding significantly. Advances in tire adhesion would await the
advent of radial-ply tires on sports cars in the early 1950s and the
super-sticky compounds formulated initially for dragsters.
The limitations of suspension and tires did not deter the quest for more
horsepower, and in the early 1930s, both Maserati and Alfa Romeo
introduced twin-engined racers in a search for higher absolute speeds.
The twin-engine craze was international, as Bugatti used pairs of Royale
engines to power high-speed trains. It remained for Mercedes-Benz, in
1936, to introduce an independently-suspended race car which would
confront more directly the problem of harnessing available horsepower
by keeping the tires on the ground.
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But the use of twin engines had a surprisingly salutary effect. Alfa's twin-engined effort, the Tipo A, placed two supercharged 6C1750 engines side by side, complete with two transmissions and two parallel driveshafts. Since the two engines could handle the differential action required between the two rear wheels, the final drive was nothing more than a pair of ring-and-pinions driving stub axles on a solid rear housing. Four Tipo A cars were built, and the model won the Coppa Acerbo and the Susa-Moncenisio hillclimb, neither especially noteworthy races. The road holding capabilities of the Tipo A, however, were noteworthy.
I am convinced that Jano and his Alfa engineers did not understand the reason for the Tipo A's superior traction, but they clearly knew that it offered an advantage. In retrospect, we now understand that the dual-driveshaft layout reduced the torque reaction under acceleration which tries to lift a driving wheel, especially in a turn. Thus, when it came time to design a new Grand Prix car, Alfa retained as much as possible of the Tipo A driveline while consolidating the two separate Tipo A transmissions into a single unit to save weight. The compromise forced the introduction of a single differential fitted just behind the transmission. From that differential, two driveshafts angled out to stub-axles driven by ring/pinion gears in the fashion of the Tipo A. The power unit for this new chassis was an enlarged and refined version of the 8C2300. The basic design remained, but with the new 8-cylinder Tipo B engine, Alfa cast the head and cylinder as a single unit, swapped intake and exhaust sides, and fitted separate superchargers for the front and rear sets of four cylinders. There were numerous other modifications, such as drilling the camshafts through for lightness, but the basic design of the Tipo B Grand Prix engine was a clear crib of the production 8C2300 powerplant. The Grand Prix car was properly called the Tipo B, but was unofficially referred to as the P3 as a follow-on to the world-championship P2 (the GPR was never called the P1). The Tipo A was a single seat car but, because it was a prototype and the Tipo B a series-production item, the Tipo B is usually credited as being the first true monoposto Grand Prix car. Seventeen Tipo Bs were produced, according to Fusi.
In point of fact, the monoposto configuration of the Tipo B is a testimony to the increasing reliability of the automobile. The riding mechanic was an important companion on the earliest cars when it came to tire-changing or replacing worn or broken parts: by the mid-'30s, his offices had become unnecessary.
I need to say something about the unit construction of the Tipo B engine. With the 6C1750, Alfa had cast some cylinder heads and blocks as single units, a practice which was the favorite Bugatti configuration. Clearly, this technique eliminated the danger of head-gasket leakage (which, so far as I know, was never a problem with the 6C cars -- though my own 6C1750 did suffer a blown gasket, due to my negligent maintenance). On the Tipo B engine, the valves seated directly on the aluminum head. On the "production" 8C2900B cars, valve seat inserts were fitted. Clearly, the maximum length of the valve was a function of the cylinder's diameter and the angle of the valve as it projected into the cylinder. The downside of this unit design is that a valve grind is a truly major operation. On some Bugattis, in fact, a valve grind began with the removal of the rear axle, then the removal of the driveshaft, transmission and, finally, the entire engine so the head/cylinder block could be dismounted.
In racing trim, the Tipo B engines proved singularly reliable and rendered Alfa virtually unbeatable in the 1934-35 seasons. In 1936, the Mercedes-Benz and Auto Union cars appeared to contest the introduction of a new formula which specified a 750 kg weight limit. Jano and Alfa were clearly satisfied with an existing, and very successful, design. The Germans, on the other hand, were able to re-visit basic premises. To simplify the situation: Alfa was running a 3-liter engine successfully, but both Mercedes and Auto Union independently determined that a 4-liter engine was feasible under the 750 kg formula. The difference in displacement, combined with the improved aerodynamics and independent suspensions pioneered by Mercedes and Auto Union, put a sudden end to Alfa's superiority. The German ascendancy corresponded to the following Alfa efforts, all feckless:
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Copyright March, 1996
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