1955 Alfa Romeo 750 Competizione by Boano Numbers built: 2 Although Alfa Romeo had officially stopped producing competition cars in the early 1950s, the companys engineers continued to explore options to return to the manufacturers very successful roots. One the projects that came closest to fruition that decade was a sports racer destined for the popular under-1500 cc class. The stillborn racer was dubbed the 750 Competizione and two prototypes were actually built. The 750 in the type name was a reference to the recently introduced Giulietta road car, which was known internally as the 750. The sports racer was based very loosely on the Giulietta but most of the important components were either heavily modified or purpose-built. The chassis and body fell under the latter and were actually built by Abarth and Boano respectively. Serving mainly as external contractors, the two companies did follow the designs as laid down by Alfa Romeo. Judging from the sophisticated chassis design, the 750 Competizione was certainly a serious project. The car used a boxed pressed steel platform chassis, which together with the sheet steel body formed a unitary construction. Considering the chassis type used, it was no surprise Abarth was called in to help with production as most of that companys cars also featured steel platform chassis. Carried over from the Giulietta, suspension was by double wishbones at the front and a live axle at the rear. While Abarth built the chassis, the Alfa Romeo engineers focused on the design of the engine. This was a four cylinder based on the engine found in the Giulietta. For its new purpose, it received a slightly wider bore and a considerably longer stroke. As a result, the displacement increased from 1290 cc to 1488 cc. Breathing through two twin-choke Weber carburettors, the small four produced an impressive 145 bhp at 8000 rpm. It was mated to a five speed gearbox. Boano completed the 750 Competizione with a striking Spider body that was distinctly different from all Alfa Romeos that came before or since. Somewhat similar to the designs Boano did for Abarth, the design included fenders with pronounced leading edges, particularly on the front of the car. Another typical Boano design element was the exposed exhaust that exited just behind front left wheel and ran parallel with the sill. The only real cue that the car was in fact an Alfa Romeo was the grille centre section. As mentioned above, two prototypes were built. They were subjected to extensive tests but never raced before the project was axed. Among the reasons for this drastic decision were teething problems during testing, the success of the production based Alfa Romeos on the track and the companys determination to continue its focus on mass-produced models. Both examples have survived and at least one is in full running order. engine Light Alloy Inline-4 position Front Longitudinal valvetrain DOHC, fuel feed Twin Horizontal Twin-Body Carburettors displacement 1488 cc / 90.8 in³ bore 78 mm / 3.07 in stroke 82 mm / 3.23 in compression 10.0:1 power 108.1 kw / 145 bhp @ 8000 rpm specific output 97.45 bhp per litre bhp/weight 210.14 bhp per tonne body / frame Aluminum Body over Abarth-Developed Boxed-Steel Chassis driven wheels RWD front tires 5.0 x 15 rear tires 5.0 x 15 front brakes Drums rear brakes Drums steering Rack & Pinion f suspension Transverse Arms w/Coil Springs, Coil Springs, Telescopic Dampers r suspension Solid Axle w/Longitudinal Arms, Coil Springs, Telescopic Dampers curb weight 690 kg / 1521 lbs wheelbase 2120 mm / 83.5 in front track 1220 mm / 48.0 in rear track 1240 mm / 48.8 in length 3470 mm / 136.6 in transmission 5-Speed Manual final drive 4.54:1 top speed ~220 kph / 136.7 mph
Posted on: Wed, 29 Oct 2014 09:38:15 +0000