Wossner Forged Pistons and PEC Rod Set Focus RS Mk2 and ST225

Wossner Forged Pistons and PEC Rod Set Focus RS Mk2 and ST225


Wössner are regarded by Europe’s leading motor sport engine builders as being the piston of choice when building an engine not only to perform, but to withstand the stresses and duress’s of competition life.


Wössner pistons feature a unique PTFE coating on the skirts and a grade of 4032 Alloy (T6) which allows the engine builder to run a closer piston to bore tolerance then he might do on another make of piston.


This helps remove the slapping noise during cold start, common place among engines running forged pistons due to larger then OE bore clearances. The crowns of the pistons are also polished to better resist detonation on a high performance engine.


Polishing allows a more even spread of heat inside the chamber which will help prevent "hot spots” on piston crowns. Price includes all piston rings and gudgeon pins.


Part Number K9489
Engine Type Focus RS Mk2 & Focus ST 2.5
OE Bore Size 83.00mm
Bore Sizes Available

83.00mm - 2521cc

83.50mm - 2551cc

Stroke 93.2mm
Dome/Bowl Volume +11.5cc
Pec Comp. Ratio Focus RS Mk2 - 8.5:1

Focus ST Mk2 - 8.5:1

OE Comp. Ratio Focus RS Mk2 - 8.5:1

Focus ST Mk2 - 9.0:1

Comp. Height 28.4mm
Valves Per Cylinder 4
Cylinders 5
Rod Configuration

H-Beam - G0164

I-Beam - G0258

Con Rod Length C/C 143.00mm
Small End Diameter 23.00mm
Small End Width 22.00mm
Big End Diameter 53.00mm
Big End Width 25.65mm

*On a Focus RS engine, this will give the factory Compression ratio of 8.5:1

If used to convert a Focus ST engine, this will lower the compression ratio from the factory 9.0:1 to 8.5:1*

Bolt Specifications:

PEC rods are designed to withstand roughly 225hp per cylinder (typically 900hp on most 4cyl engines) and on the ARP 2000 series 3/8 bolts normally provided & have an 8,500 RPM safe operating limit (engine specific).

In some cases, we recommend using the ARP custom age bolts available from us. This increases the hp threshold to 250hp per cylinder and raises the RPM limit to 9,000 however as every engine is different, these numbers are not guaranteed for every configuration.

If in doubt, please contact us for advice.

What's in the box?


Wossner pistons:

  • 5x Wossner forged pistons
  • 5x Wossner piston rings sets
  • 5x Wossner gudgeon pins
  • 5x Wossner circlips sets
  • 1x Wossner sticker
  • 1x PEC piston installation guideline sheet


PEC connecting rods:

  • 5x PEC forged steel connecting rods (choose between H-beam or I-beam style)
  • 10x ARP 2000 series / ARP custom age 625 connecting rod bolts (choose from options)
  • 1x ARP fastener assembly lubricant
  • 1x PEC connecting rod installation guideline sheet


Available Options:
Con Rod Bolt Options:
ARP 2000 Series Bolts (Included)  
ARP 625 Series Bolts (Optional Upgrade) (+£258.63)  
Focus RS Mk2 Rod Style:
I-Beam - G0258  
H-Beam - G0164  
K9489 Size Options:
83mm - K9489DA  
83.5mm - K9489D050  
    Compression Ratio
    Bore Size
    Workshop fitted
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