chapter 8
This page is dedicated to the memory of Pat Braden who died on August 25, 2002.
Chapter 9
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.
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:
1935
1936
1937
1938
1939
KTUD Alfa Romeo main page!
Copyright March, 1996
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