6-Port Induction System (6PI)

Auxiliary Port Valve:

The auxiliary port valve is part of what Mazda calls the "6-Port Induction" system. This system helps improve volumetric efficiency at high engine speeds by opening a third intake port into each rotor housing when the engine speed increases above 3,850 rpm.

At low engine speeds, the valve covers the auxiliary port. This prevents the air/fuel mixture from being forced out of the rotor housing back into the intake system as compression begins. At higher engine speeds the valve is open. At these high speeds, the high velocity and momentum of the air/fuel charge continues filling the rotor housing during the first part of the compression phase. The rotor closes off the port before any of the air/fuel mixture can be forced back into the intake system.

The valve itself is a hollow drum closed at one end with a window near the closed end. The valve is rotated on its long axis by an actuator diaphragm that reacts to pressure from the AIR pump. When AIR pump pressure is sufficient, the actuator rod extends, rotating the valve. In this position, the window uncovers the auxiliary port into the engine. Air pump pressure to the actuator is regulated by a computer controlled solenoid valve. The solenoid valve prevents air pressure from operating the auxiliary port valve until the engine speed exceeds 3,850 rpm.