PISTON, PISTON RING, PISTON PIN [SKYACTIV-G 2.0]

2016 – MX-5 – Engine

The piston in the cylinder of the cylinder block moves reciprocally while transmitting pressure to the piston pin and connecting rod when the air-fuel mixture combusts.

The piston ring consists of the compression ring (top ring, second ring) and the oil ring, and has the following functions.

The compression ring prevents leakage of pressure in the cylinder from the piston circumference.
The oil ring clears off extra engine oil adhered to the cylinder wall.

The reciprocating movement of the piston is transmitted to the connecting rod by the connection of the piston pin to connecting rod.

The piston is made of aluminum alloy with superior high-temperature strength and excellent thermal conductivity.
The piston has a cavity on the top surface. As a result, the initial combustion flame is prevented from hitting the top surface of the piston to reduce cooling loss.

The sliding resistance and the part mass have been minimized by reducing the surface area of the piston skirt and reducing the thickness.
An offset piston has been adopted in which the center of the piston pin has been offset from the piston center. As a result, piston slap is suppressed.

A barrel-face ring for the top ring and a taper under cut ring for the second ring have been adopted.
A three-piece oil ring consisting of a side rail and spacer have been adopted for the oil ring.
The tracking capability to the cylinder wall has been improved by reducing the thickness of the piston ring. As a result, a low-tension piston ring has been implemented without increasing the engine oil consumption, and the sliding resistance has been reduced during reciprocating movement.