RSR Big-Bore Piston and Cylinder Set, 98mm. Porsche 911 3.0 Carrera / 911 SC 1976–83  ❭  10010303204

This Mahle RSR big-bore piston and cylinder set is intended for compatible Porsche 911 3.0 Carrera and 911 SC engine builds from 1976–83. Its 98mm bore works with a 70.4mm stroke to increase displacement from 3.0 litres to approximately 3.2 litres.

Fits

• Porsche 911 3.0 Carrera 1976–77
• Porsche 911 3.0L / SC 1978–83

What This Product Does

The set replaces the original pistons and cylinders during a complete engine rebuild or displacement conversion. Forged pistons are paired with Nikasil-coated ST52 steel cylinders to provide the matched running clearances required within an air-cooled flat-six engine. A 10.3:1 compression ratio and deeper valve pockets suit a correctly planned RSR-style build and provide an alternative to the established Max & Moritz configuration.

Functions

• Increases compatible 3.0L engines to approximately 3.2L
• Forms the combustion chambers and supports compression sealing
• Transfers combustion force through the connecting rods to the crankshaft
• Provides controlled piston movement and heat transfer
• Supports oil control through matched pistons, cylinders and rings

Technical Details

• Bore diameter: 98mm
• Specified stroke: 70.4mm
• Compression ratio: 10.3:1
• Forged pistons with deeper valve pockets, off-centre pin bores and 22 x 58mm wrist pins
• ST52 steel cylinders with Nikasil-coated running surfaces
• Supplied with six cylinders, pistons, fitted rings, wrist pins and retaining clips
• Approximate kit weight: 9.78kg

The off-centre piston-pin arrangement is designed to manage piston movement and operating noise. Rings are installed on the pistons before supply, helping to keep the matched assembly together during preparation. Piston rings and wrist pins must not be modified. Final measurements remain essential before assembly, including deck height, piston-to-cylinder clearance, ring condition and valve-to-piston clearance.

Symptoms of Fault

• Low or uneven compression readings
• Excessive oil consumption or blue exhaust smoke
• High crankcase pressure or pronounced blow-by
• Piston slap, knocking or other internal engine noise
• Scored, distorted or worn cylinder surfaces found during inspection
• Damaged piston crowns, skirts or ring lands
• Metallic debris discovered in the oil or filter

Why Replacement Matters

Worn pistons, rings or cylinder surfaces can prevent the combustion chamber from sealing correctly. Replacing these components as a matched set helps restore suitable clearances, compression and oil control. The engine should be inspected and measured by an experienced air-cooled Porsche engine builder, as the final specification depends on the crankshaft, camshafts, cylinder heads, induction, exhaust, fuel system and ignition settings.

FAQs

• Is this a standard-size replacement set?
  No. It uses a 98mm big bore to convert a compatible 3.0L engine to approximately 3.2L.
• Are the pistons and cylinders matched?
  Yes. The components are supplied together to maintain the intended sizing and clearances.
• What should be checked during installation?
  Confirm all critical clearances, compression requirements, cylinder-head compatibility and the complete engine specification before final assembly.
• Does the engine require a running-in period?
  Yes. Follow the engine builder's procedure for initial start-up, oil selection, ring bedding and subsequent inspection.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

10010303204

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