The reformist revolution implemented with the Uno would not have been truly complete without the FIRE engine. In 1983 at the time of the spectacular launch at Cape Canaveral, under the bonnet of the Fiat small car, in fact, the glorious 45 HP 903 still beats. A long-stroke four-cylinder pushrod and rocker arm derived from the one that has equipped the “127” since its debut, way back in 1971. An engine of exceptional longevity considering that its origins date back to 1955 when, with the factory code 100D.000 and with a displacement of 633 cc, it was mounted on the 600. The dynamic qualities of the chassis and the lightness of the construction are enough to mask its weakness but the Uno deserves more. Fiat has already started the design of a new generation engine in collaboration with Peugeot, whose development was hindered by the strong trade union conflict of those years, with strikes which systematically prevented technicians from accessing the plants. However, they continue to work in makeshift offices located in the rooms of a modest hotel in Corso Francia but, despite their commitment bordering on sacrifice, they are unable to show up in time for their appointment with Uno.
The race of Fire
The engine arrives a couple of years after the launch and the delay translates into a precious opportunity to consolidate the image of the model which is now configured as an “open” and flexible project capable of welcoming any type of innovation that becomes available . The collaboration with Peugeot, which will then withdraw from the project when it comes to sharing its production, proves to be decisive because it introduces a working method based on the progressive consolidation of the results achieved through written reports. A very uncommon practice at Fiat in those days. But the French company also deserves credit for having convinced Fiat to adopt electronic ignition instead of the traditional distributor. A solution also shared by the designer Ildo Renzetti who was also able to make the eight-cylinder 500 designed by engineer Carcano for the Guzzi Grand Prix run at over 10,000 rpm even in the presence of a conventional ignition system. The name FIRE was born as an acronym to summarize its production and design specificities: Fully Integrated Robotized Engine. Translated into operational methods it means “design to produce”. The objective is to obtain maximum integration between the technical solutions adopted and the technologies of the plant, to achieve the best possible compromise between costs, quality and performance.
The project in Termoli
With the FIRE project, the Termoli plant and the engine become a necessary consequence of each other. Quality is no longer entrusted to the traditional end-of-line control whose necessary objectivity is compromised by a certain discretion based on the achievement of production objectives, but spread throughout the entire plant. The production process is divided into groups of processes which are carried out by a team that organizes the division of tasks internally, in perfect autonomy. On a design level, the results are considerable. The number of components drops from 350 on the “903” to 270, the mechanical processes from 350 to 308 and the number of controls on the line rises from 7 to 93. The engine architecture favors simplicity. Cast iron block, crankshaft on five supports housed in a crankcase of very small size and weight, light alloy head, two aligned valves per cylinder, controlled by an overhead camshaft driven by a toothed belt and roof-mounted combustion chamber .
The development of Fire
A simplicity made possible by the adoption of computerized design systems, especially as regards the analysis of the flows in the intake and exhaust ducts and the combustion methods of the air/petrol mixture in the combustion chamber. These are the two parameters on which the volumetric efficiency of the engine and, consequently, the value of the driving torque largely depends. In this regard, the comparison with the old “903” is enlightening: the power is unchanged, around 45 HP at 5600 g/1', but is obtained at a lower speed of over 600 g/1' while the maximum torque goes from 6 kgm at 3500 g/1' at 7 kgm at 3000 g/1'. In terms of performance, the results are even embarrassing. Renzo Porro, head of the experiment, kept the results of a comparative test with the “128” engine in his drawer for days. A gain of 22″ on the acceleration without using the gearbox from 40 km/h up to the maximum speed is such an extraordinary result that it irremediably disavows the work done up to then. Great care is dedicated to containing maintenance costs: the valves do not require the usual clearance recovery.
Its unique features
A characteristic obtained without resorting to complex and expensive hydraulic tappets but only through the choice of suitable materials. FIRE is designed to allow maximum development potential as commercial and technical objectives evolve. A flexibility that over time has allowed strong increases in displacement (from 999 to 1400 cc), the adoption of twin-cam heads with four valves per cylinder, up to doubling the power compared to the original engine and the development of common rail diesel versions , while maintaining the lower part of the engine unchanged and therefore with limited changes to the production systems. The combination between the Uno car body and the new engine is what is needed to “turn on” a second stage capable of sending the Fiat small car stably into orbit at the very moment in which, two years after launch, it is now the novelty effect has worn off. To achieve the objective, however, it is necessary for FIRE to acquire its own personality based on the exceptional nature of the technical and technological contents that characterize it and in line with a communication strategy aimed at amplifying all the interventions that have the Uno as their object. Hence the idea of promoting the engine from a component, albeit an essential one, to the role of absolute protagonist, giving it an independent identity with respect to the model. When FIRE appears by surprise, at the end of the presentation press conference organized in the Termoli plant, installed on the robocarrier, the robotic trolley which is the basis of the flexible production system, a non-ritual applause underlines the success of the operation. It is not only the technical qualities, which have yet to be subjected to road test examination, that impress but also and above all the result of the intervention of a brilliant designer, Rodolfo Bonetto (in the picture)which, for the first time, does not deal with the definition of bodywork and cockpits but with the stylistic integration of the different elements that make up the engine in perfect coherence with the aim of generating an autonomous image of FIRE
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