Without a doubt, Aprilia’s V4 1100 engine is one of the most powerful engines and with a better delivery of those in its category.
Indeed, Noale’s V4 is an example of smooth delivery of torque and horsepower. However, Aprilia joins the vogue for variable valve timing (VVT). This has been seen in some patent drawings that have appeared.
Why? With Euro5 (and more to come shortly), variable valve timing has become more important than ever.
This is because sports engines need more valve crossover at high revs (intake and exhaust are open at the same time) to achieve better performance. However, at low rpm, this means that less gasoline is burned in the explosions, passing it to the exhaust, and therefore more polluting gases are generated.
The variable distribution is capable of changing the valve crossing at different revs (less crossed at a few turns -the intake valves open later, less gasoline enters- and more at high revs), so that low emissions and good performance at high revs.
BMW, Ducati, Suzuki, Kawasaki or Yamaha already have VVT engines. However, Honda was the pioneer in using this system. He first rode it in 1983 on his sporty CBR400F, and popularized it with his famous VFR800 in 2002 with its VTEC.
The Golden Wing brand is also studying this system for its CBR1000RR-R.
The Aprilia VVT
Aprilia’s V4 uses a variable valve timing (VVT) system similar to the one Suzuki launched on its 2017 GSX-R1000R.
The Japanese motorcycle uses a mechanical system, made up of a dozen metal spheres inside a disc and which vary the distribution when the spheres move using centrifugal force.
Aprilia’s system is similar, but the Italian brand only uses three spheres, making it simpler and lighter than the Japanese one.
Counted in a very simple way, in the Aprilia engine we see the metal spheres inside a disc (4) next to the distribution gears (3). At high rpm, these spheres (5) move outwards through channels using centrifugal force, varying the angle of the valves. After a few turns, some springs (6) push the spheres back to their original position.
The relative simplicity of the system means that the architecture of the current V4, which is mounted on both the RSV4 and the Tuono V4, does not have to be changed much.
Without a doubt, at the autumn EICMA we will have to see these engines mounted on the new versions of their sports cars.