Alfa Romeo 33 Stradale: a racing car with number plates

The Alfa Romeo 33 Stradale is a mid-engined sports car built by Alfa Romeo, and was the fastest commercially available car over the standing kilometre when it was introduced. Eighteen examples were produced between 1967 and 1969. “Stradale” is Italian for road-going, and the car was derived from the Tipo 33 sports prototype.

Alfa Romeo 33 Stradale at a glance

History of the Alfa Romeo 33 Stradale

From 1966 sportscar racing was divided into Group 6 “prototypes”, with hardly any limits until the maximum engine size was cut to three litres after 1967, and Group 4 “sports cars”. A prototype could be homologated as a Group 4 car if at least 50 were built within 12 months, as the Ford GT40 Mk I and Ferrari 250 LM had been. The requirements included a spare wheel, luggage space, an ignition lock, lights and wipers, which were things found on a potentially street-legal car but not on a pure racer. Porsche had already succeeded in homologating over 50 906 Carrera 6s in early 1966, while Ferrari failed to build enough of its Dino 206 S and had to race it as a prototype. Alfa Romeo meanwhile ran the Tipo 33 as a prototype, and also built a road car from it.

The 33 Stradale was based on the Autodelta Tipo 33 racing car. The car was designed by Franco Scaglione and built by Carrozzeria Marazzi, and was shown at the Paris Salon on 5 October 1967. The first prototype was built at Autodelta’s workshop in Settimo Milanese beside the Tipo 33 “Periscopica” racer. The two prototypes are the only ones with the dual-headlight arrangement; Scaglione redesigned it for the production cars because of regulations on minimum headlight height. Marazzi claims to have built 18 chassis: five were used for six concept cars by Pininfarina, Bertone and Giugiaro/Italdesign, and eight for production cars.

Body and chassis

The 33 Stradale is regarded as the first road-going production car with forward- and upward-opening butterfly doors, hinged both at the base and at the top of the windscreen frame, which let the side windows curve seamlessly into the roof. Most cars have an aluminium body on an aluminium tubular chassis. Because they were built by hand every car differs in details; later cars had vents behind the wheels to let hot air from the brakes escape. The suspension was derived directly from the Tipo 33, with upper and lower control arms at the front and double trailing arms at the rear.

Engine

The engine bore no resemblance to the mass-produced units in Alfa’s other cars, though it is closely related to the V8 of the Montreal. Designed by the race engineer Carlo Chiti with an oversquare 78 × 52.2 mm bore and stroke, it was an all-aluminium 1,995 cc V8 with dry-sump lubrication, SPICA fuel injection, four ignition coils and two spark plugs per cylinder, and four chain-driven camshafts; the rev limit was 10,000 rpm. Unlike the Montreal it kept the racing engine’s flat-plane crankshaft. It produced 230 PS in road trim and 270 PS in race trim, though output varied from car to car because the drivetrains were built by hand. Everyday use was awkward, with no door locks and limited ground clearance.

Design and features

• Doors: the first road car with butterfly doors hinged at the sill and the windscreen frame.
• Engine: a 2.0-litre racing V8 with a flat-plane crankshaft and a 10,000 rpm limit.
• Construction: hand-built aluminium body on a tubular chassis.

Alfa Romeo 33 Stradale versions

• Prototypes (1967–1968): two cars with dual headlights; one in magnesium.
• Production cars: about eight Stradale chassis, with a 10 cm longer wheelbase than the race cars.
• Concept cars: six one-offs by Pininfarina, Bertone and Giugiaro on five chassis.

The Stradale idea of a racing car on the road also appears in the Ford GT40 and the BMW M1. More cars are in our Alfa Romeo collection.

Sources

• Alfa Romeo 33 Stradale, English Wikipedia: background, history, specifications