Guide: Alfa Romeo Tipo 33 Stradale
Background
After winning back-to-back World Championships with the mighty 158 and 159 ‘Alfetta‘ Grand Prix cars in 1950 and 1951, Alfa Romeo announced their withdrawal from works participation in motor sport.
Despite the fleeting C52 Disco Volante and 6C 3000 CM programmes, they were true to their word; the firm’s competition involvement was subsequently limited to a range of small capacity production-based GT cars built for privateer use.
However, by 1962 the racing bug was beginning to bite and a new subsidiary, Delta Automobili, was created at Alfa Romeo’s behest. The operation was run by ex-Ferrari designer, Carlo Chiti, and Ludovico Chizzola.
Charged with the design and manufacture of a new tube chassis GT racing car (the Tubolare Zagato or TZ), Delta Automobili became Alfa’s back-door racing division.
In March 1963, the operation was rebranded as Autodelta and became Alfa Romeo’s official competition department.
With the successful TZ, TZ2 and GTA models behind them, Autodelta were commissioned to create an all new two-litre Group 6 Prototype for the 1967 season. The resultant Tipo 33 was unveiled at Alfa’s Balocco test track in March 1967. That season it went head-to-head with other two-litre Prototypes from Porsche, Ferrari, Alpine and Matra.
Whereas Group 6 had no minimum production requirement, Group 4 (the next rung down as Group 5 was for Special Touring Cars) stipulated 50 cars had to be produced in twelve consecutive months. Such was the Tipo 33’s speed, Alfa Romeo thought a Group 4 version would be a shoe-in for class honours. Accordingly, in September 1967 it was announced that a batch of 50 new Group 4 cars would be constructed.
Anticipating the bulk of production would be sold for street use, the new model was officially designated Tipo 33 Stradale.
Chassis
The Tipo 33 Stradale was based on the big tubed perimeter chassis of the 1967 Tipo 33 Group 6 car.
This competition spaceframe comprised two light-alloy side members that doubled up as fuel tanks. Magnesium front and rear subframes carried the suspension, engine, gearbox and differential.
Suspension was via wishbones, helical springs and anti-roll bars with radius rods also installed at the back. Fully adjustable telescopic dampers were fitted all round along with ventilated disc brakes (inboard at the rear).
Inevitably, the Stradale featured a number of subtle differences from the Group 6 version.
The wheelbase was extended by 100mm to 2350mm which freed up additional cockpit space. The two magnesium bulkheads were reinforced with steel to afford greater impact protection. The central chassis tubes were formed from steel instead of aluminium.
13-inch magnesium wheels measured 10-inches wide at the front and 12-inches wide at the back. They were originally shod with Dunlop tyres.
Engine & Gearbox
Like the rest of the Tipo 33, Autodelta’s compact and lightweight all-alloy 90° V8 was a complex piece of kit. With two chain driven overhead camshafts per bank, four ignition coils, dry-sump lubrication, Lucas fuel-injection and 16 spark plugs, the average Alfa dealer wouldn’t have known where to start.
A displacement of 1995cc was achieved thanks to a bore and stroke of 78mm and 52.2mm respectively. With compression set at 11.0:1, peak output was 256bhp in race trim.
By comparison, the Stradale motor was slightly de-tuned. Compression was reduced to 10.0:1, the cam timing was altered and the Lucas injection was switched to a SPICA unit. As a result, peak output dropped to 230bhp at 8800rpm.
Whereas the Group 6 competition version used a six-speed Colotti gearbox with a ZF limited-slip differential and single-plate hydraulic clutch, the Stradale came with a five-speed ‘box.
Bodywork
The original Tipo 33 had been styled in-house at Autodelta. For the Stradale, Alfa Romeo turned to Franco Scaglione’s design agency, Carrozzeria Sargiotto.
The new bodywork was fabricated from aluminium instead of glassfibre and Scaglione’s magnificent creation ranked among the 1960s great automotive designs.
The first two prototypes had twin headlights stacked one above the other mounted underneath clear plastic covers. Chassis’ 105.33.01 was the original prototype and chassis 150.33.12 was intended for use at the Le Mans 24 Hours but did not get completed until 1968.
Both prototypes had their bodywork manufactured under Scaglione’s supervision at the Autodelta works.
Partly because of the delays between each example being finished, there were a number of differences between them. Most notable was the roof-mounted wiper on chassis 01 and the rear wing air vents on chassis 12.
By contrast, production versions came with single headlights and their aluminium bodies were fabricated and fitted at the new Marazzi coachworks in Milan. Marazzi was born from the remnants of the recently bankrupted Carrozzeria Touring.
Cars would arrive at Marazzi with drivetrains installed ready for bodywork. As each car was built entirely by hand, no two were 100% identical.
The production car’s nose was given a slimmer profile than the Tipo 33 racer and the whole design appeared more delicately crafted.
As the competition version had been a Spyder and the Stradale was a Berlinetta, access to the cockpit had to be carefully considered. Both versions stood barely a metre high so, to enable easier entry, the Stradale featured elaborate dihedral butterfly doors. These were hinged at the top of the roof and opened upwards and forwards. Panoramic side windows cut substantially into the roof and were split by a body-coloured T-bar.
Some cars came with fixed single pane windows, others had sliding plexiglass inserts but most had split panes with wind-down side glass.
Front and rear body sections were hinged at either end. The back featured a single piece screen through which the injection trumpets were displayed.
The tail had a minimal rear overhang. Single circular lights were fitted each side and a bank of vents were located atop the trailing edge. Two large air vents were carved out from behind each rear wheelarch to improve air circulation. These vents appeared on most production versions while some cars also had similar looking cutaways behind the front wheels as well.
Other car-to-car differences could be found around the front indicators, trim for the nose-mounted intake, the shape and location of the front scuttle duct, the windscreen wiper quantity and mounting locations, badging, wing mirrors and the rear deck air vent which was sometimes a single bank and other times split into four.
Interior
Interiors differed from one chassis to the next according to the owner’s requirements.
Seats were sometimes trimmed in fabric and other times leather. Most examples came with sound-insulating carpet.
A simple dash was upholstered in vinyl. The main instrument pod located behind the three-spoke steering wheel housed a 10,000rpm tachometer. Additional instrumentation was located off to the right.
The dash and transmission tunnel were linked by a central control panel that was home to an array of switchgear.
A chrome ashtray was usually located at the back of the transmission tunnel but was best not used if your car had fixed windows.
Weight / Performance
Alfa Romeo quoted a weight of 700kg.
The Tipo 33 Stradale had a top speed of 160mph and 0-62mph time of 4.9 seconds: this made it the fastest accelerating road car available at the time.
Such performance came at a not inconsiderable price though: the Stradale retailed at Lire 9.75m compared to Lire 7.7m for a Lamborghini Miura.
Production
The first prototype was displayed at the Monza Racing Car Show which took place after the Italian Grand Prix in September 1967. An official presentation was then made at the Turin Motor Show in November.
The first single light production version was unveiled at the Autodelta works in January 1968.
All bar one of the Stradales was painted red. The solitary blue example (built on chassis 111) was ordered by Count Giovanni Agusta who also had the car equipped with helicopter seats supplied by his aviation company.
In addition to the pair of four headlight prototypes, a further nine Stradales were manufactured over the next 18 months. Three additional examples may also have left the works but as yet these cars are undocumented. The enormous price and labour-intensive construction process dictated the original plan for 50 cars never materialised. Instead, Alfa Romeo decided to focus on the front V8-engined Montreal.
The last 33 Stradale was completed in March 1969.
Chassis numbers of the production versions ranged from 750.33.101 to 118. Five of these were supplied without bodywork to coachbuilders who created showstopping concepts. Two went to Bertone (for the Carabo and Navajo), two to Pininfarina (for the P33 Roadster, 33/2 Coupe Speciale and P33 Spider Speciale Cuneo) and one to Ital Design (for the Iguana).
Chassis 113 was re-numbered 133 for its superstitious first owner while chassis 114 was never built as a Tipo 33 Stradale. Instead, the number was later used for homologation purposes when Autodelta created a one-off 33/TT/12 for the 1975 Giro d’Italia.
Competition History
Although less expensive and more effective competition cars were available, at least two 33 Stradales were purchased for sporting use.
Chassis 103 was delivered to the SCAR Autostrada Alfa Romeo dealership in Florence and 106 was purchased by Paolo Laureati. Both examples featured lightweight interiors, sliding Plexiglas side windows and single wipers. They were predominantly used in domestic hillclimb events throughout 1968 and 1969.
Text copyright: Supercar Nostalgia
Photo copyright: Alfa Romeo - https://www.alfaromeo.com
