The whole time Giuseppe Busso was running the mechanical development office before and during the Giulietta period, he was involved in race car design. But the work was continuously interrupted by the more important road car projects. I have told about the original 6c3000 that was designed to do one better than the old 6c2500 Competizione. It eventually became the 6c3500 CM and 6c3500 PR but they never really made an impact on the racing community. It did cause a lot of attention in period and it ran with the 4100cc Ferrari’s and the Lancia D24 as well as the emerging Mercedes-Benz 300SL, but there were too many failures. The tubular space-frame chassis broke (poor Consalvo Sanesi crashed in almost every race), the steering broke and the differential and engine also broke. This shows that the design was right at the limit - where it should be! But the Alfa Romeo team never succeeded in getting it really good. They simply weren't allowed to put the necessary hours into the improvements.
This project was put on hold because of the Giulietta development, and during the 1954-1958 period the only racing projects were basically inspired by outside teams; like Abarth or Conrero. Busso followed them closely and I think he must have been disappointed, because the results were not very good - and more importantly the methods and efforts were also not terribly good. From what I can read, Giuseppe Busso would really have loved to assign some of his own staff to the work.
It started during 1955 when Carlo Abarth approached Alfa Romeo with the wish to use the new 1300 engine in his own 207a box-steel chassis that had been used with significant success in both Europe and USA with Fiat 1100 engines. Just think what he could achieve with the Alfa engine; maybe even stretched to 1500cc where Abarth (and everybody else) was loosing to the OSCAs. Alfa Romeo made a special 1500cc interim version of the engine for Consalvo Sanesi's Giulietta Spider in the 1957 MM (where the poor man once again almost lost his life, when the gearbox got stuck in two gears at the same time).
Busso assigned one of his young engineers, a certain Carlo Chiti, to the project, and together with Abarth they designed the 750 Competizione. It was tested extensively and in the end it even resembled a typical Alfa Romeo with a proper scudetto. But it was never raced - and I bet that Busso cancelled the project because it was too soft in the chassis. And rightly so, it wouldn’t be right to have a race car that handled worse than the standard Giulietta Spider - and Alfa Romeo also ran the Giulietta 1500 Spider Monoposto, remember.
Carlo Abarth didn’t give up and came back two years later with a tubular chassis design. He must have listened to Busso and the Alfa Romeo engineers, who were still disappointed because the promising 6c3500 tubular car had been withdrawn without reaching its real potential. Busso keeps coming back to the tubular design in his mémoires and it was actually much more sophisticated than the thick-tube Ferrari standard chassis, so I get it, why it would bug him not to be able to show what they could achieve on the race tracks. So, Abarth returns with the Alfa-Abarth 1000 for the 1958 Turin motor show, and it is a gem.
Beautifully skinned by Franco Scaglione at Bertone and fitted with a reduced-stroke version of the Giulietta engine - made by Portello. But this chassis was also way too flexible and it all ran into a dead end. Fiat didn’t like the prospective of Abarth moving away from Fiat engines, but after this they seriously took up collaboration with Abarth, and Ivo Colucci, Busso’s chassis man, was lured away by Carlo Abarth. That combo was about to make some serous racing cars. Busso states that the engine was too expensive for small-series production anyway. But just think about it: bore/stroke of 74x58 mm and 998cc - it’s a screamer.
Around this time Giuseppe Busso was busy with the systematic redesign of the 750 series. Alfa Romeo was moving up; into the next league of mass production with the 101 series. But he also designed a 6-cylinder version of the 101-engine. Adding two more cylinders, the idea would bring the displacement to 2 liters and it would be a serious contender for 2000cc sportscar racing. But they agreed on a 2.6 liter design and the engine wasn’t used until 1962 when the 102-series came out.
Enter Virgilio Conrero. He had made some interesting redesigns and alterations earlier in the decade using 1900 parts. He had designed a twin-plug version of the engine; with his own castings, and he had made some Gilco/Ferrari type race chassis with Alfa Romeo 1900 mechanicals for his own team and for wealthy friends. Now he was starting to use the 1300 Giulietta engine and while working closely with Portello he started to develop and build tubular chassis prototypes.
So for 1960 the real Alfa Romeo racer success (besides the success of the Giulietta Zagato in GT-racing) was definitely the Alfa-Conrero 1150 Spider. It ran in the Targa Florio and at Le Mans, but when you look at the design of the rear suspension it is evident that it was too fragile. It didn’t have an upper control arm and this was actually what eliminated it from the 24h race as is clearly visible when you look at photos of the stranded car. This time the engine had a reduced bore - retaining the block and crankshaft. Not at all interesting for Busso, who had orighinally fallen in love with Wifredo Ricart's square engine philosophy back with the 512 voiturette racer.
But Satta and Busso took over the main ideas from Virgilio Conrero’s chassis and drive line. They started a project called 105. It had the Giulietta engine and general suspension and brake layout, but it used the inboard drums of the Alfa-Conrero 1150; and they strengthened the rear part of the chassis and doubled the tubing along the sills - under the doors. This was what eventually became known as the TZ - with Ercole Spada at Zagato as bodywork designer.
First they did a Spider version because Busso was still dreaming of the 6c3500 PR but it turned out to be too slow. Then they put a roof on it and during a very slow gestation period of 4 years it finally came out as the Coupé we know today. In the meantime it had been fitted with disc brakes and it had the bigger 1600cc engine. But the chassis was still showing Conrero design and the steering and suspension was Giulietta. It has nothing to do with the 105 series - other than the number; but that was only because it originally had been the first car to use the 105 designation.
The cars were built at Autodelta. At first in Udine, because Alfa Romeo wanted the race works away from Portello (just like when Scuderia Ferrari had been set up in Modena during the late 1920s) but once the TZ started winning races, the directors in Milano would complain about the UD number plates and Autodelta was resolutely moved to Settimo Milanese.
The TZ evolved into the TZ-2, but it is basically the same car; still a Giulietta, so to speak. If you compare a TZ and a TZ-2 under the skin, you will see that the only difference is that the steering column goes over the dashboard cross member in the TZ (there is a dent in the tube in that position); while on the TZ-2 it goes under the cross tube (but the dent is still on top). The significant differences between these cars are of course the bodywork; much lower fiberglass for the TZ-2 and aluminum for the TZ. And the fact that the TZ-2 ride height is lowered for 14” wheels, while the TZ has the original 15” Giulietta wheels from when the first prototypes had 3-shoe drum brakes.
From then on Giuseppe Busso lost the job of designing and developing Alfa Romeo race cars. Carlo Chiti and Autodelta took over, while he and Orazio Satta would focus on road cars.
Moving on to de Dion rear suspension - at last!