Cosworth EJ25 Forged Piston (EJ255 / EJ257)
Cosworth draws on over 65 years of experience in motorsport piston manufacturing and has stood for the highest quality and performance for decades. .
The Cosworth EJ25 Pistons feature an especially robust Boxed- & Bridged-Forging-Design.
This significantly increases rigidity and load capacity. At the same time, a very short piston pin and the lightweight Slipper-Skirt design reduce weight.
Manufactured from a proprietary 4032 aluminum alloy, these pistons, combined with an offset piston pin position, provide particularly smooth operation with minimal blow-by. An Xylan coating on the piston skirt reduces friction and improves conformity to the cylinder bore.
The included High-Performance piston rings (manufactured to the highest Japanese standards) minimize blow-by and oil consumption even under high continuous loads. In addition, high-strength piston pin retaining rings with increased preload are used, remaining reliably in position even under extreme forces.
Recommended Use
Ideal for high-performance road vehicles and track-day setups up to approximately 600 hp.
Technical Data
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Compression ratio: 8.2:1 (8.6:1 with D25 cylinder heads)
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Bore diameter: 99.5 mm or 99.75 mm
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Material: 4032 aluminum alloy
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Piston pin wall thickness: 0.220in
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Application: Subaru EJ255 / EJ257
