ENGINE: an exclusive 65? V4
The pursuit of maximum engine performance in a supersport motorcycle must be accompanied by a perfectly positioned engine in the frame. Mass centralisation, swingarm length and optimum weight distribution are ingredients for achieving the most competitive bike, together with the pursuit of maximum power and perfect power delivery.
Aprilia engineers have known for years that a narrow V-layout is the ideal technical solution for obtaining a class-beating chassis architecture that emphasises the performance of the engine. A 65-degree V-4 cylinder engine, the only solution that could ensure unparalleled performance, enabling the outstanding chassis architecture that has defined all Aprilia racing motorcycles for the past twenty years.
Besides the exclusive configuration that makes the 65? V4 unique around the world, the technical advantages of the Aprilia four-cylinder engine can be summarized as follows:
. Perfectly integrated into the frame, with optimal mass centralization and minimized inertia for benchmark agility.
. Absolute slimness, its overall width is comparable to that of a twin cylinder motorcycle, with huge benefits in terms of ergonomics and aerodynamics.
.The compactness of the engine makes a very oversquare cylinder layout possible, using large bores and subsequently larger valves, helping the engine breathe more freely and achieve higher engine speeds (14,000 usable rpm).
The engine was entirely developed by Aprilia's Research and Development Division, aiming at offering record performance and ridability in compliance with the strictest reliability and quality standards.Aprilia's V4 design exploited the most powerful computer calculation programs currently available on the market, resulting in a highly optimised engine layout. By slightly opening the angle of the V (with respect to a 60? V engine), the designers could make use of the larger space to optimize the inlet ducts and maximise engine efficiency.
The unique timing system makes extremely compact heads possible (measuring only 250mm high at the rear), especially in the area beneath the frame spars, which are thus much narrower than would otherwise be possible. The lateral timing chain drives the intake camshaft only and follows an optimized path for improved timing precision and chain durability.
A gear pair at the centre of the cylinder bank transmits drive to the exhaust camshaft. This solution made it possible to obtain an extremely compact head in the exhaust area. The V4 is even more compact than the V60 Magnesium twin mounted on the RSV 1000 R. A counterbalancer dampens vibrations even more than in a 90-degree Vee engine. The crankcase has integrated cylinder liners for maximum rigidity and consistent performance.
Electronics of the Future
Aprilia's RSV4 Factory engine features full ride-by-wire technology. There is no direct connection between throttle grip and the throttle valves, which are completely controlled by a latest generation Marelli control unit. Each bank has a dedicated servo motor actuating the two relevant throttle bodies only. Hence the two banks, and subsequently the quantity of fuel injected, can be managed independently. While this solution has been tried and tested by Aprilia, it has never been applied before on such a powerful engine, thus opening up practically infinite possibilities for power delivery control. This technology immediately benefits the rider who, thanks to the triple mapping that can be controlled directly from the handlebar, can change the engine delivery mode and thus the motorcycle's temperament at any time.
The 65-degree vee angle and...
The 65-degree vee angle and hybrid cam drive help keep the RSV4's 999cc engine short and compact.
The fuel supply uses two injectors per cylinder: one injector is placed downstream of the throttle valve and a "shower" injector is placed in the airbox and starts working at high loads and revs. This is complemented by electronically controlled variable length intake ducts. At low revs and loads, the long duct favors torque and smooth power delivery. When top performance is required, the upper part of the intake duct raises, thus shortening the duct and leaving the engine free to express its full power potential. A butterfly valve in the exhaust further optimizes power delivery.
The transmission was also designed according to the most advanced criteria. To underscore the racing soul of the V4 engine, a cassette gearbox is used, with a multi-plate wet clutch disc equipped with a mechanical slipper system to optimize engine braking torque and ensure stability under hard braking.
Lastly, in order to minimize weight, Aprilia's new engine makes large use of ultralight materials; all valve covers and external housings are made from magnesium.
Engine capacity: 999.6 cc
Architecture: 65? V4
Power: 180 HP @12,500 rpm
Valve arrangement: 4 valves per cylinder (Titanium and Nymonic) operated directly by a camshaft driven by a mixed chain/gear system (lateral timing chain, central gear train)
Fuel system: Magneti Marelli electronic injection with 2 injectors per cylinder and integrated independent Ride by Wire system for each bank. Three mappings selectable from handlebar. Electronically controlled variable length intake ducts
Maximum rpm: 14,100 rpm
Compression ratio: 13:1
Transmission: 6-speed direct-control cassette gearbox
Clutch: multiplate wet clutch with mechanical slipper system
Exhaust system: 4 into 2 into 1 headers with oxygen sensor and single silencer with integrated catalytic converter and exhaust valve.
This CAD drawing of the valve...
This CAD drawing of the valve train shows the Aprilia's cam drive system that uses a chain to drive the intake cam, which in turn drives the exhaust cam.
Using eccentric inserts allows...
Using eccentric inserts allows adjustment of steering rake angle on the RSV4.