Aprilia RSV4

The 999cc 65-degree V-4 powering the new Italian superbike is not only significant in that it’s a departure from Aprilia’s use of V-Twins, the compact V-4 was also developed and built entirely in-house at Aprilia. Austrian motor-building giant, Rotax, has supplied the 60-degree liter capacity Twin for the RSV1000 (known as the Mille in early iterations) and Tuono models, seemingly from time immemorial.
The Noale, Italy-based bike maker certainly drew from its deep well of V-Twin experience in the RSV1000, but the company now wanted a more powerful mill. To achieve the lofty goal of a claimed 180hp at 12,500 rpm, and to surpass power produced by competitor’s engines, Aprilia saw no other choice than the V-4.
Claudio Lombardi, chief architect of the Aprilia V-4, stated that extreme compactness of the powerplant was of primary importance.
That the Factory’s heads are 150mm narrower than the typical performance-oriented inline-Four’s 400mm head reveals Lombardi achieved the goal of a skinny engine. The compactness of the engine makes a very oversquare cylinder layout possible. Using large bores and subsequently larger valves helps the engine breathe more freely and achieve higher engine speeds. The Factory’s engine redlines at 14,100 rpm; compression ratio is 13.1.
Key to the engine’s slimness is the layout of the valve train.
A timing chain in each head drives the intake camshaft only, while a gear at the center of each intake camshaft drives a gear on the exhaust camshaft. This design lends to an extremely compact head in the exhaust area. Aprilia states the V-4 is even more compact than the 60-degree Twin in the RSV1000R.