Since its recent integration into the Piaggio Group, Aprilia has been able to give free rein to its mechanical creativity, backed up by the new owner's development Euros as well as a solid reputation for quality that gave us the much-appreciated RSV1000 lineup as well as the ground breaking RS Cube in MotoGP. Unfortunately, a lack of funds at the time had prevented the RSV in Superbike, and the Cube from winning consistently despite a design markedly more advanced at the time than any of its Japanese or Italian rivals.

Aprilia has turned a page with the all-new RSV4, dropping the Rotax V-Twin in favour of an in-house design.

But that's all history now, as Aprilia has turned the page with the all-new RSV4, dropping Rotax's excellent V-Twin in favour of a house-designed, 65-degree V4 engine with a balance shaft, a configuration that no other major manufacturer uses for serious sport and high performance street bikes.

The Joys Of A V4
Using a V4 configuration offers several advantages over an in-line four configuration:

• The engine is narrower and can thus be mounted lower in the chassis while still providing good clearance on full lean, as well as lowering the center of gravity of the machine,
  
• The cylinder heads are lower, leaving more room at the top for a large airbox and intake system, using the preferred with efficient vertical stacks,
• The crankshaft is shorter and thus stronger and able to sustain higher rpm and deliver more power,
  
• Crankshaft configuration can be set to emulate side by side V-Twins, to produce more low-end torque and improve traction on corner exits, while keeping light pistons and connecting rods to allow higher revs and thus develop more power,
• The narrowness of the V4 allowed designers to streamline the fairing and thus reduce drag, an important factor in this day and age of diminutive riders that will prove its worth in higher top speeds on the track next year.

Overall length of the V4 engine-gearbox assembly should logically exceed that of the more common inline four, but this shortcoming is reduced by the use of superimposed shafts in the transmission, a practice started by Yamaha with its R1 in 1998, which saves up to 100mm in total length, and is now emulated by all major manufacturers.

A shorter engine is an important factor in current racing machines, and here is why: Since the position of the front of the engine is dictated by the position of the radiators and the wheel, a shorter engine means that the counter shaft sproket is farther forward in the chassis than with a longer engine.  In turn, this allows the designers to fit a longer swingarm (For better traction on corner exit) without having to lengthen the wheelbase (Thus preserving agility in changes of direction).

The RS Cube MotGP bike, introduced in 2002, featured (too) many complex features at the time: electronic ignition and injection, traction control, variable intake manifold lengths and throttle-by-wire systems - all of which are now available on production bikes!

So Aprilia isn't afraid of taking the leap, and the RSV4, to be ridden by Max Biaggi and Troy Corser in the 2009 World Superbike Championship, certainly contains some more surprises for us, especially since Piaggio Group's massive investment power has solved the money problem that had impeded development of previous generations of Aprilia race bikes.

2009 Aprilia RSV4 Superbike