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The Power of Eight

By Aaron Frank, Photography by Moto Guzzi & Phil Aynsley

Moto Guzzi was a major player in the early days of Grand Prix roadracing. The Italian firm won the 250cc World Championship in 1949, ’51 and ’52, and five consecutive 350cc titles from ’53-’57. Guzzi’s horizontal-singles were less successful in the premier 500cc class, however, where they were consistently outgunned by Gilera, then MV Agusta inline-fours. In late ’54, hoping to close this gap, legendary Guzzi engineer Giulio Cesare Carcano created one of the most daring machines in motorcycle history: the Otto Cilindri V8.

Why leap from one cylinder to eight? Carcano saw no advantage in building another inline-four that would, at best, be only incrementally better than the rest. An inline-six could make more power, but would be too wide. A pair of 250cc inline-fours arranged in a 90-degree Vee, on the other hand, could be narrower than a 500cc four and, with increased valve area and a higher rev ceiling, produce even greater horsepower. In the unique racing calculus of power, packaging and weight, the V8 made perfect sense.

Carcano’s liquid-cooled, DOHC V8 was a masterpiece of miniaturization. With 16 delicate valves, eight tiny pistons, eight individual 20mm Dell’Orto carburetors, eight separate coils, eight threadlike exhausts and eight contact-breaker points, the V8 was fantastically complex. And the math added up: Oversquare (44.0 x 40.5mm) engine geometry delivered 78 horsepower at a stratospheric 12,000 rpm—a 10-horsepower advantage over the rival fours.

The Otto Cilindri was remarkably compact. Its pale-green dustbin fairing was just 30mm wider than Guzzi’s 350cc single, and a 330-lb. racing weight gave a better power-to-weight ratio than any GP racer built to date. It was ferociously fast, but ill-handling and fragile. Aussie rider Ken Kavanagh debuted the V8 at the 1955 Belgian GP and dropped out with a broken crank. The V8 raced twice more that year—at Senigallia and Monza—and DNFed both times.

The V8 didn’t finish a single race in ’56, either. Kavanagh led Imola’s Coppa d’Oro (Gold Cup) until the water pump broke. Two-time 350cc World Champion Bill Lomas set the fastest lap at the Dutch GP and then promptly broke, while Kavanagh crashed out. Lomas qualified on pole at the Belgian GP only to suffer ignition problems during the race. Meanwhile, Kavanagh was so terrified by the handling on Spa’s long curves that he never raced the V8 again.

A total engine redesign improved reliability for ’57, with encouraging results. Giuseppe Colnago won an Italian Championship round at Siracusa, Sicily—the V8’s first win—then Dickie Dale won the Coppa d’Oro, but Dale’s fourth-place finish in the Isle of Man Senior TT was the best Grand Prix result. Clocked at 178 mph on Spa’s Masta Straight—a speed that remained unmatched for 20 years—the V8 was indisputably fast. But development stopped when Guzzi withdrew from GP racing at the end of ’57, preventing the world from witnessing the V8’s true potential.

So ended one of the finest chapters of motorcycle racing history, in which Moto Guzzi won a remarkable 3329 races, 11 Isle of Man TTs and 14 world titles. The firm went on to enjoy sporadic success in other series, but never competed in the Grands Prix again. The V8 never returned to competition. Only five were ever built, and just two originals remain, both displayed at the Moto Guzzi factory museum in Mandello del Lario.

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