Alfa Romeo Tipo 33

The **Alfa Romeo Tipo 33** was a prototype sportscar raced by the Alfa Romeo factory team in the World Sportscar Championship between 1967 and 1970. It won 2 races and the 1967 World Sportscar Championship in the sub-2000cc category.

## History

Alfa Romeo started development on the 33 Stradale road car in the early 1960's. The car had some success in European touring car competitions, where regulations limited changes from the road-going version. Seeing the success of the Shelby Cobra Daytona, Alfa committed to a World Sportscar Championship run with the 33 for the 1967 season. However, there was little time between this announcement and the first round of the season, so few changes could be made to the touring car.

## Specifications

**Body and Chassis**

The 33 Stradale is the first production vehicle to feature dihedral doors, also known as butterfly doors. These were retained for early versions of the race car but were later changed as they could not be opened in the event of a rollover. The car's aluminium body panels and spaceframe chassis were built by hand, so subtle differences in handling could be felt between cars. Both road and race versions featured vents on the wheel arches, which allowed high pressure air to escape. These had the added benefit of cooling the disc brakes.

**Engine and Transmission**

Technical Specifications
 Displacement
 Power
 Torque

The engine fitted to touring and early WSC models bore little resemblance to the Stradale's, taking more from the V8 of the Alfa Montreal. Race engineer Carlo Chiti designed an oversquare 1995cc engine which featured fuel injection, four ignition coils and twin spark plugs per cylinder. The road version's chain-driven camshafts were converted to be gear driven to operate the 2 valves per cylinder.

Alfa Romeo developed a bespoke 6-speed transaxle for the Stradale which was carried over to the race car.

## Tipo 33/2

Although the 33 placed 1st in class at the 1967 1000km of Spa-Francorchamps, the win was purely through attrition. It lapped several seconds slower than its nearest competitor, the Chevrolet Corvette. The car was expected to be more competitive at the Charade 12hr race. However, it was again off the pace. The team's #1 driver, Jean Nguyen, took the result as an insult in front of his home crowd. His protests lead to the development of the Tipo 33 into the 33/2 in time for the 1967 24 Hours of Le Mans.

In the 3 weeks between the races, the car underwent radical changes. All of the glass was removed and the windscreen replaced with acrylic. this alone shed 30kg from the car. The heavy and dangerous butterfly doors were removed and replaced with conventional doors made from fibreglass. Overall, 120kg was removed from the car, bringing its curb weight to 580kg.

The removal of the engine cover allowed for modifications to the air intake, as well as a brand new engine head, which was taller and now featured 4 valves per cylinder. This allowed the rev limit to increase to 10,000 RPM. Along with exhaust modifications, which made the car noticeably louder, the engine was now producing upward of 250 hp.

For the first 3 rounds of the championship, the car ran on non-adjustable dampers and springs which, even with the low weight of the car, allowed for considerable body roll. These were changed for a suspension system which allowed a much stiffer setup and lower ride height.

During practice runs, the 33/2 was recorded at 282kph on the Mulsanne Straight. Still slower than the 295kph the Porsche 906 was capable of, but a marked improvement on the 260kph reached at Monza.

Despite the top speed deficit, the Tipo 33/2 was 1st in class and 3rd overall at Le Mans in 1967.