Perhaps the most fully realized of all V-8 motorcycles is the legendary Guzzi V8 Grand Prix racer first seen in 1955. Displacing just 499cc, the 90-degree layout was purported to crank out nearly 80 hp, which was a 10-horse advantage over inline-Fours of the era. Combined with its aerodynamic dustbin fairing, the Guzzi was able to achieve a top speed of 171 mph.

But the 328-lb GP monster was beset by myriad mechanical problems during its three years in competition, amassing only three GP wins and the 1957 Italian Championship. Just five were ever built. More than 60 years later, it sounds as fierce as any motorcycle ever has.