A trademark of the Ferrari 250 GTO
The SNAP it’s a exhaust terminal formed by two coaxial tubes and vanes inserted into the circular crown. A remarkable aesthetic effect that also embellished a well-known tail like that of the ’62 Ferrari 250 GTO: it had 4 of them, also very protruding, and they were perfect for enhancing the image of power already evoked by the endless nose. I have a clear memory of it from when I saw one for the first time: it was Edoardo Lualdi’s GTO who had just won the Coppa Luigi Fagioli hill climb in Osimo (AN), 1962.
So as not to fall into rhetoric, I leave out all the emotions of the moment, however the question of the exhaust pipes, as we called them, remained in my mind. Then in my father’s auto parts shop, for years there hung a poster of a muffler factory depicting these terminals on the tail of a Ferrari. In short, I just couldn’t forget them. And I always thought they were mounted for theaesthetics or at most to improve the sonority of the engine… but not really. Not long ago, I accidentally came across an advertisement from the time, relating to these accessories… the memories came back and the curiosity to find out more. The surprise was precisely that of discovering that the company IPRAN of Milan had built it SNAP (patenting it) with the aim of improve performance: the objective was in fact to increase the air-fuel charge by acting on a more effective evacuation of the burnt gases. There is no data on this matter, but a significant confirmation comes from the installation instructions provided by the company at the time: in addition to indicating the assembly positions, they reported the measurements of the new jets (leaning) to be replaced in the carburettors, a sign that combustion could take place under more favorable conditions.
The idea of creating exhaust pipes with the operating principle of ejectors it was not new, but IPRAN had the merit of creating them aesthetically appealing, even though it was not specific to the sector: there are few historical traces, but it seems that its main activity was the production of propellers for both the aviation and naval sectors. The denomination SNAPan acronym that stands for Sload Nonegative TOria Pression, suggests the operating principle; a premise on the geometry of the ducts is useful: the actual exhaust pipe flows into the circular crown equipped with shaped blades to swirl (further) the flow of burnt gases, while the central pipe is short and, via a bifurcation, is connected to the 2 mouth-shaped side openings; the exhaust gas, having a pulsating speed (related to explosions) gives rise to cyclical energy exchanges: when the exiting gas has the maximum speedsucks in the air from the central pipe and accelerates it, while when it has the minimal, is the accelerated air, which, due to inertia, in turn sucks in the gas, thus lowering the external back pressure. It is this phase of low pressure which, propagating backwards in the exhaust pipe, causes better emptying of the combustion chamber, an indirect objective which has already been mentioned.
Returning to the historical context, in the 1960s the market for car accessories was thriving, the trend was to make the car sportier: IPRAN supplied Ferrari and used its winning image to promote its entire product line; it was a widespread strategy among the suppliers of the Maranello company, which had already achieved global fame. The Latin speaker “Super” sanctioned the widespread desire for performance, it qualified everything… from mufflers to fuel. Then slowly the market began to change, less and less sports customizations and, in general, more and more approval constraints, especially on exhaust systems: already in the 1970s these sophisticated terminals had practically disappeared, all that remained were those made from simple chromed tubes, these mounted for aesthetic effect only; a practice that continues today with… fake exhaust pipes. The SNAP but it was true… with its exemplary balance between simplicity, aesthetics and functionality, it still retains an intact charm.
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