Mahle Motorsport Pistons & Piston Rings

Shop by Vehicle pages for S55 and EJ20 cars:

• BMW M2 (F87) 2016-2021
• BMW M2 Competition (F87) 2018-2021
• BMW M3 (F80) 2014-2019
• BMW M3 Competition (F80) 2016-2019
• BMW M4 (F82 / F83) 2014-2020
• BMW M4 Competition (F82 / F83) 2016-2020
• Subaru Impreza WRX (GC) 1994-2000
• Subaru Impreza WRX STI (GC) 1998-2000

• Forged piston sets: Mahle PowerPak forged pistons for the Subaru EJ20 2.2L stroker (92.50mm bore, 8.2:1 compression ratio), and Mahle Motorsport forged piston sets for the BMW S55 (84mm bore, 10.2:1 compression ratio), including a coated version listed for F80, F82 and F87 chassis.
• Piston ring sets: Mahle MS universal piston ring set for a 100mm +0.13mm bore with 1.0/1.0/2.0mm ring widths, supplied file fit.

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Match these identifiers to your engine and build specification before ordering:

• Engine code: for example Subaru EJ20 or BMW S55. Piston sets are engine-specific.
• Bore size and oversize: for example 84mm, 92.50mm, or 100mm +0.13mm. Pistons and rings must suit the finished bore size.
• Stroke, rod length and pin diameter: the BMW S55 set (set of 6) is listed for an 89.6mm stroke, 144.35mm rod and 22mm pin.
• Compression ratio and dish volume: for example 8.2:1 for the EJ20 stroker, or 10.2:1 with a -10.5cc dish for the S55.
• Chassis code: the coated S55 set is listed for F80, F82 and F87.
• Ring widths: the universal ring set uses 1.0/1.0/2.0mm top, second and oil ring widths.
• Alloy: 4032 alloy expands less with heat, which allows tighter piston-to-wall clearances and quieter running. 2618 alloy is more ductile and better suited to extreme, detonation-prone racing use.

Mahle's technologies include Grafal® skirt coating to reduce friction and cylinder wall wear, phosphate dry-film coating to protect pin bores from galling, and hard-anodised top ring grooves on some kits to resist micro-welding under high boost.

Installation by a professional is recommended. Fitting forged pistons usually involves:

• Machining the cylinders to suit the piston size.
• Setting piston-to-wall clearance to Mahle's specification for the alloy used.
• Filing file-fit rings to the correct end gap for your application.

Check Mahle's specifications for your part number before the engine is assembled.

Where can I buy Mahle forged pistons in Australia?
Chicane Australia carries Mahle Motorsport forged pistons and piston ring sets and ships Australia-wide from the NSW Central Coast. Search by Mahle part number, or contact our team with your engine code, bore size and compression ratio for help choosing the right set.

Should I choose 4032 or 2618 alloy for my build?
4032 alloy has a higher silicon content, so it expands less when hot. This allows tighter clearances and a quieter engine, which suits high-performance street cars. 2618 alloy is more ductile and resists detonation better in extreme racing use. It needs wider clearances, which can cause piston slap on cold starts.

What is Grafal coating?
Grafal® is Mahle's proprietary resin-based graphite skirt coating. It reduces drag, friction and scuffing on the cylinder walls, and is designed to stay on the piston for its service life.

What does file fit mean on a piston ring set?
File-fit rings are supplied with extra material at the ends. The end gap is then filed to suit the bore size and how the engine will be used.

Which BMW models suit the coated S55 piston set?
The coated Mahle Motorsport S55 set (84mm bore, 10.2:1 compression ratio) is listed for the F80, F82 and F87 chassis with the S55 engine.