The original and genuine Cosworth DFR piston set, designed and manufactured by Cosworth for their 3.5 litre DFR engine.
These pistons are forged in house by Cosworth from 2618 high tensile strength aluminium alloy. The forging is designed specifically for this piston to give the best grain flow in the most highly stressed areas. Once forged, Cosworth then machine, inspect and pack the piston set.
Each set contains eight Cosworth PA1154 pistons. Also included are high strength gudgeon pins and clips plus high performance compression and oil control rings.
Starting at the crown, each Cosworth DFR piston comes with pre-machined valve pocket cut-outs. The crown includes an “intruder” to maximise compression ratio.
Next , the oil control ring groove includes an array of oil drain holes. Any oil that is scraped by the rings from the wall of the cylinder bore can drain back through these holes into the crankcase or sump. As a result, these holes help to stop oil from building up behind the ring. If left to accumulate, this oil would find its way up past the rings and into the combustion chamber, creating unacceptable levels of oil burning.
Below the ring grooves is custom skirt that has been accurately machined by Cosworth to incorporate a smooth blended barrel form with an optimised profile. Furthermore, the skirt itself is coated on both sides with a xylan anti-friction coating that provides excellent wear resistance and gives the skirt a very low surface friction to help reduce any frictional losses.
- Cylinder bore diameter = 90.000/90.013 mm (Nikasil coating required)
- Gudgeon pin diameter = 23.810/23.815 mm
- Compression height (distance from pin centreline to top of crown) = 34.775/34.825 mm
- Small end width = 26.35/26.65 mm
- Ring widths = 1.00 mm top ring, 1.00 mm 2nd ring & 3.00 mm oil control ring