Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

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Dr. Porsche didn’t live to see the family sports car firm flourish, passing in 1951 just as production began to ramp up in Stuttgart, following a few years working out of what was essentially a large shed in Gmünd, Austria. Though Ferdinand’s KdF-wagen/VW and its variants certainly laid the foundation for the 356, it was his successors–specifically son Ferry and grandson Butzi–that nurtured the ancestral business into the world’s preeminent builders of sports and racing cars. Dr. Ing. h.c. F. was nonetheless a prolific and brilliant engineer in his own right, developing over the decades everything from the world’s first hybrid car in 1899, to tank and aero engines, to Auto Union’s marvelous B, C and D V16 and V12 GP racers–just a fraction of his massive and varied portfolio.

One of the Porsche patriarch’s most interesting and exotic racers never turned a wheel in competition, but still exists today, residing in Porsche’s spectacular corporate museum near its Stuttgart HQ. Designed and built in the old Gmünd workshop for small Italian firm Cisitalia, the Porsche Typ 360 was an incredibly advanced single-seater Grand Prix racer utilizing a mid-mounted, 1.5 liter flat-12 with quad camshafts, twin superchargers, and roller-bearing supported internals spinning 10,500 RPM through a sequentially-shifted 5-speed transmission driving all four wheels.

Sometimes referred to as Porsche’s E-Type, the Cisitalia GP was clearly evolved from Auto Union’s B,C, and D-Types, albeit with packaging more inline with modern, mid-engine designs–for example, note that the driver’s compartment and engine are both pushed more towards the center of the chassis, resulting in a slightly longer nose and shorter deck.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

Said chassis consisted of a chromoly tubular spaceframe underneath streamlined magnesium bodywork, mounting a radius arm/torsion bar rear and classic VW/Porsche trailing arm front. Modern, hydraulic-type dampers were found at all four corners, along with large finned drum brakes.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

All pretty interesting, but things get downright fascinating when peering into the miniature-but-mighty flat-12. Designed with a vertically-split aluminum alloy crankcase with integral water jackets, wet cylinder liners were of a 56mm inside bore, and dome pistons moved through a 50.5mm stroke. Cylinder heads used twin, widely-splayed cams, each operating a single (intake or exhaust) valve per pent roof combustion chamber.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WDTechnically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

The Hirth-type crankshaft was built-up in sections around one-piece connecting rods, and supported on roller bearings. With a diameter of 54mm–just 2mm less than the bore itself–the crank was overbuilt in the extreme, as were 18mm gudgeon pins. Rods, apart from being single-piece, were conventional, albeit short at just ~4″ long. As seen here, this results in the pistons’ skirts resting virtually on top of the journal at bottom dead center.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

Twin vane superchargers force-fed an air/fuel mixture supplied by a pair of dual-throat downdraft Weber carbs, and bench tests reportedly netted 385 HP at 10,500 RPM in a very early, underdeveloped state of tune. Porsche is said to have projected 500 HP at a ~12k rev ceiling, and probably would have achieved this goal given enough time and funding.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

Power, once directed through a fully-synchronized sequential 5-speed gearbox, was put down to the rear wheels under normal conditions, or split front/rear to aid acceleration out of corners, as selected by the driver via a lever mounted to the dash–presumably the one being grasped in the image below. This novel feature was proposed in order to help alleviate traction issues experienced with the hugely powerful (and strictly rear-driven) Auto Union GP cars, some of which were run with dual rear wheels towards the same goal.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

The legendary Tazio Nuvolari, who as an Auto Union driver in 1938 and ’39 had direct experience with the earlier Porsche designs that inspired the Cisitalia GP, was invited to drive the car, ostensibly for further development testing. In reality, publicity gained from this event was probably deemed to be of greater value.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

Ultimately, Nuvolari’s test run failed to inject much-needed finances into the project, and with development proving prohibitively expensive, key Cisitalia figure Piero Dusio relocated to Argentina in 1948 or so. Returning to Europe a few years later to repay his creditors, Dusio was also able to secure the GP car as well as a large cache of spares, all of which were then sent to South America.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

At one point Dusio attempted to secure funding from president Juan Perón, but by 1952 Formula 1 displacement rules changed, instantly crushing any hopes of the car competing as designed. This was an unfortunate turn of events, as despite being several years old by this point, the 360 GP was still very much ahead of its time and may have well proved dominant provided the proper resources.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

The Type 360 was then used to set a few South American records, including speed over a distance of 1,000 meters, which the car achieved at 233 km/h (~145 mph). It was set to race in local Formula Libre events for 1953, but a lean fuel charge led to two burnt pistons, after which the car was essentially retired. As noted above, it now resides in Porsche’s Stuttgart museum.

Technically Interesting: Cisitalia-Porsche 360 Grand Prix Flat-12/4WD

Earlier this decade a second Cisitalia/Porsche 360 was discovered, albeit in a partially-completed state. Now under restoration, there are rumors of a plan to reunite the two cars for a run up Lord March’s driveway at an upcoming Goodwood Festival of Speed, an event we definitely want to be on hand for, if only to hear the incredible little 180° 12 sing to 12,000 RPM!

Image credit: Porsche, Cisitalia, unassociated

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