Air supply unit for an internal combustion engine

Air supply unit (1) for an internal combustion engine comprising:

• an intake box (2) in communication with an external environment;
• a number of butterfly valves (3), each of which has its own internal duct (4) interposed between the intake box (2) and the intake ducts of the engine cylinders;
• and
• a distributor device (6), which includes a chamber (7) connected to the intake box (2) by means of a first air duct (8) regulated by a solenoid valve (9) and includes, for each butterfly valve (3), a respective distribution duct (10) capable of placing the chamber (7) in communication with the internal duct (4) of said butterfly valve (3);
• wherein inside the distributor device (6), each distribution duct (10) is connected to the intake box (2) by means of a corresponding air duct (11) regulated by a respective bypass screw (12) and each distribution duct (10) is connected to a corresponding regulation duct (13) that opens into an air intake (14), which is normally closed by an associated removable plug (15);
• the air intakes (14) and the bypass screws (12) being fitted in the distributor device (6) in such a manner as to be accessible from the same regulation wall (16) of said distributor device (6).