Forget everything you know about the Rotax-built V-twin employed in previous Aprilia sportbikes, this V-4 is all-new. The 65-degree angle between cylinders is wider than the 60 degrees of previous Aprilias, but narrower than the 90 degrees of Ducati V-twins and the Desmosedici RR V-4, or the Honda V-4 Interceptor. While Aprilia engineers admit this engine configuration isn't optimal for peak power--that distinction goes to an inline-four--they claim it is optimal for handling, as evidenced by its use in the Ducati, Honda and Suzuki MotoGP racers. With a single gear-driven counterbalancer in front of the cylinders, the "V" configuration is also smoother than an inline and gives the engine a natural, offbeat, "big-bang" firing order that improves traction. And it allows extremely oversquare cylinder dimensions (78 x 52.3mm--within a decimal point of an '09 Yamaha YZF-R1), which equate to 999.6cc--just shy of the World Superbike displacement limit. Those bores hold forged 13:1 compression pistons, topped by 32mm titanium intake and 28mm Nimonic steel exhaust valves, each with nested springs, set at a very flat 22-degree included angle. Dual chains spin the intake cams, which spin the exhaust cams via idler gears. Valves are opened directly via shim-under-bucket actuation. The wet-sump lubrication system features dual oil pumps housed in a magnesium sump, with temperatures held in check by an oil cooler that complements the coolant radiator. A cassette-style gearbox allows quick ratio changes for racing, while a mechanical slipper clutch replaces the old vacuum-operated diaphragm setup. Claimed output is 177.5 horsepower at 12,500 rpm and 84.8 lb.-ft. of torque at 10,000 rpm.