100 years

8CM

1933

Maserati 8CM

The Maserati 8CM was one of the brand’s first Grand Prix racing cars. It was a particularly powerful car, with a 2,991.4 cubic centimetre straight eight engine capable of delivering 240 horsepower at 5,800 rpm in its most powerful version. This was 20 HP more than the original model; an upgrade achieved by fine-tuning its combustion system and other components. However, its weak point was the chassis, derived from the slender frame of the Maserati 4CM 1100 and too flexible to manage all the power of the eight cylinder engine, which initially impaired the car’s performance.

Start of production 1933
End of production 1935
Victories 1
Chassis beams with steel section cross-members
Length 3,850 mm
Width 1,570 mm
Height 1,200 mm
Wheelbase 2,560 mm
Weight 785 kg
Engine L8, front, longitudinally mounted
Displacement 2,991.4 c.c.
Power 176 kW (240 HP) at 5,500 rpm
Top speed 250 km/h
Transmission manual 4 speed

The 8CM on the racecourse

Un destino di successo

Although Maserati did not yet have much experience in Grand Prix racing cars, the development of the Maserati 8CM was completed very quickly. The first car, with chassis number 3005, was completed as early as March 1933, and was driven to victory in the Tunis Grand Prix of the same year by Raymond Sommer. However, its debut was not very promising, since the car had to be withdrawn due to technical problems. Nonetheless, these teething troubles were soon dealt with and by the time of the Montecarlo Grand Prix, the second car, with chassis number 3006, was ready for delivery to Zendher, who took part in the Monaco event. The results achieved by this first version of the 8CM did not impress because its chassis was too flexible to withstand the forces generated by the powerful eight cylinder engine and the huge 400 millimetre drum brakes. The drivers who complained about these problems, which arose from the excessively lightweight chassis derived from the Maserati 4CM 1100, included Giuseppe Campari. At the time, Maserati was focusing more on innovations in engine design than on research into chassis construction.

Tazio Nuvolari: the problems are resolved

Tazio Nuvolari’s arrival at Maserati marked a real turning-point for the 8CM. Nuvolari, who had already owned an 8CM, purchased from Sommer, knew all about the chassis’ limitations. Maserati already had a car, the 3007, which Scuderia Ferrari had ordered but never taken delivery of, sitting ready in the workshop. Nuvolari decided to have this car modified by Decimo Campagnoni, his personal mechanic, and Luigi Parenti, the Maserati mechanic. The chassis’ front structure was stiffened and a new steering box was installed to replace the one from the Fiat 522 used previously; the brake system was also modified to provide smoother operation. Thanks to these changes, Tazio Nuvolari’s Maserati 8CM number 3007 won on its debut at the Belgium Grand Prix.

The evolution of engineering

The Maserati 8CM was built on a Maserati 4CM 1100 chassis, which was particularly lightweight due to its small size. At the front, instead of the straight four engine, it was fitted with an extremely powerful 2,991.4 c.c. eight cylinder in-line unit, featuring some sophisticated construction details. Roots supercharger with Weber carburettor upstream, timing system with two valves per cylinder and double overhead camshaft and forced lubrication were just some of the characteristics of this unit, with bore of 69 and stroke of 100 millimetres. Over time, the original 220 horsepower was increased by an additional twenty, above all through changes to the combustion system, with the compression ratio upped from 5.26:1 to 6.35:1. Maximum power output was now achieved at 5,800 rpm compared to the previous 5,500 rpm. The car had single ignition, with drivers using Bosch or Scintilla magnetos, while the type of tyres used ranged from Pirelli to Englebert and Dunlop. In 1934 Maserati modified the car to comply with the rules for the various races. The 8CM had a fuel tank with capacity from 150 to 170 litres mounted behind the cockpit, in a position which would be particularly dangerous in case of an accident. For fast refuelling during races, the car was fitted with two unusual inlets known as the Maserati Type, even though the patent was held by Giuseppe Bonora of Bologna. There was also an oil tank of 43 litres underneath the driving seat, while the car was fitted with enormous hydraulically operated 400 millimetre drum brakes. Over the yeas, the various drivers had their cars modified in different ways, with engines of more than 300 horsepower and a number of experiments that even included the combined use of two different Roots superchargers, a solution later rejected in favour of a simpler system with just one compressor.

Technical details

01

The Maserati 8CM was built on a Maserati 4CM 1100 chassis, which was particularly lightweight due to its small size.

02

Over time, the original 220 horsepower was increased by an additional twenty, above all through changes to the combustion system, with the compression ratio upped from 5.26:1 to 6.35:1.

03

The car had single ignition, with drivers using Bosch or Scintilla magnetos, while the type of tyres used ranged from Pirelli to Englebert and Dunlop.

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