Details
The 815 was designed and developed by ex-Alfa Romeo engineers Alberto Massimino[4] and Vittorio Bellentani, advised by test driver Enrico Nardi.[1] The designation "815" was based on the car's eight-cylinder, 1496 cc engine bore/stroke of 63 x.[1][3] This engine was largely based on the four-cylinder, 1.1 L engine of the Fiat 508 C Balilla 1100.[1][5] In concept, it was two 508C engines placed end to end, but it used a specially designed aluminium block built by Fonderia Calzoni in Bologna for integrity and light weight and a five-bearing crankshaft and a camshaft designed and built by AAC to get the traditional straight-8 timing and balance. The compression ratio was increased to 7:1 from 6:1 in the original Fiat engine.[6] The engine used Fiat valve gear, cylinder heads (two 508C heads per engine), and connecting rods.[1] Instead of the two original Fiat distributors, AAC manufactured a single distributor to avoid synchronization issues.[6] The engine was high-tech for the time, with a single camshaft in block, two valves per cylinder, and a semi-dry sump lubrication system.[5] Four Weber 30DR2 carburettors were specified[1][5] for a total output of 75 hp at 5500 rpm.[1]
The 815 used a Fiat four-speed transmission with the Fiat gears replaced by gears made in-house by AAC.[1] The transmission was integral to the engine block.[5] The car had independent Dubonnet suspension with integral shock absorber at front, with a live axle on semi-elliptic leaf springs and hydraulic shock absorbers at the rear.[1]
As Mille Miglia regulations required that racing car chassis be based on production models, the AAC 815's chassis was also derived from the Fiat 508 C Balilla.[7]
The bodywork was done by Carrozzeria Touring using Itallumag 35, an aluminium/magnesium alloy,[1] and was done in long, flowing forms with integrated wings.[5] The bodywork weighed 119 lb.[1] The complete car weighed 625 kg and attained a maximum speed close to 170 km/h.[5] Chassis 020, built for Rangoni, was fully trimmed in leather and had luxuriously detailed exterior trim, including extra chrome and a recessed fuel filler cap. Ascari's car, 021, was more spartan. Touring also developed a design for a proposed convertible version of the 815. Drawings and a scale model were produced but this was not further developed due to the onset of World War II.[6]
