Piston And Connecting Rod Assembly
| ITEM | DESCRIPTION |
|---|---|
| 1 | Circlip |
| 2 | Piston |
| 3 | Gudgeon pin |
| 4 | Circlip |
| 5 | Connecting rod identification |
| 6 | Connecting rod bolts (2 of) |
| 7 | Connecting rod bearings (2 of) |
| 8 | Connecting rod |
The connecting rods have fracture-split bearing caps. The bearing caps are produced by fracturing the opposing sides of the connecting rod at the bearing horizontal center-line. As well as being easier to manufacture, when reassembled the fractured surfaces interlock to form a strong seamless joint. The cylinder position is etched on adjoining sides of the joint to identify matching connecting rods and bearing caps. The connecting rod bearings are selective split plain bearings. The connecting rod bearing is 'bismuth coated tri-metal', which is a manufacturing process that layers the bearing material to produce a higher load capacity for improved durability.
Piston And Connecting Rod Orientation
| ITEM | DESCRIPTION |
|---|---|
| 1 | Piston and connecting rod assembly, cylinders 4-6 |
| 2 | Piston and connecting rod assembly, cylinders 1-3 |
| 3 | Connecting rod bearing cap (6 of) |
| 4 | Bolts (12 of) |
| 5 | Connecting rod lower bearing (6 of) |
When installing a connecting rod, ensure the back of the connecting rod faces the center of the 'vee'.
The pistons are fitted with three rings. The piston crown incorporates a pronounced bowl. This forms the combustion chamber, which promotes swirl and turbulence necessary for good combustion and improved emissions. In addition, the piston skirt has a molybdenum-coated surface, which counteracts scoring of the cylinder bore and piston.
The piston also incorporates a double wave gallery within the piston crown to enhance piston cooling. The pistons are supplied oil by means of spray jets located in the cylinder block oil gallery. These jets ensure optimum piston cooling to counteract the high temperatures generated by the combustion process.
Each piston is installed on a gudgeon pin located in a bushing in the connecting rod.