Engine Analysis: HPE Evolution and Fluid-Mechanical Dynamics
The special series is marketed with two powerplants from the HPE (High Performance Engine) family, both single-cylinder, four-stroke, four-valve units featuring liquid cooling and single-point electronic injection managed by Magneti Marelli control units.
310 cc HPE Unit
This represents the dimensional and thermal evolution of the previous 300 cc unit. It develops a maximum power of 27.7 HP. The valve timing diagram and the cam profile have been optimized to increase torque values at low-to-medium revs. This configuration reduces the engagement times of the centrifugal clutch during urban stop-and-go restarts, improving thermal efficiency and limiting oil churning phenomena inside the crankcase.
400 cc HPE Unit
This represents the variant oriented toward medium and long-range touring. It delivers 35.9 HP of maximum power and a torque of 37.7 Nm. This powerplant adopts a longer connecting rod and a lightweight high-resistance piston to reduce first-order alternating inertia forces. The optimization of the exhaust line and the fluid dynamics of the intake ducts has yielded a linear delivery curve, reducing acoustic resonances and vibrations transmitted to the footboard.