Wiseco K563M81AP 81mm 9.6:1 Forged Piston Set for 98-99 VW Audi 1.8T 20V Golf/A4

Engine Fitment

• 1998-1999 VW/Audi 1.8T 20V (Engine codes: AVC, ANB, AWU, AEB, APP, ARY, AUQ -- 20mm wrist pin)

Vehicle Fitment

• 1998-1999 Audi A3 (8L, 1.8T 20V)
• 1998-1999 Audi A4 (B5, 1.8T 20V)
• 1998-1999 Audi A6 (C5, 1.8T 20V)
• 1998-1999 Audi S3 (8L, 1.8T 20V)
• 1998-1999 Audi TT (8N, 1.8T 20V)
• 1998-1999 Volkswagen Golf Mk4 (1.8T 20V)
• 1998-1999 Volkswagen Passat (B5, 1.8T 20V)
• 1998-1999 Volkswagen Octavia (1.8T 20V)
• 1998-1999 SEAT Toledo (1.8T 20V)

Fitment Notes

• 1998-1999 model years only -- 2000+ 1.8T 20V engines switched to 19mm wrist pins; not compatible
• Standard bore (81.00mm) -- no cylinder machining required at stock bore
• Confirm engine code before ordering -- not all 1.8T applications are 20V
• Piston-to-valve clearance must be verified during assembly
• Set of 4 pistons -- covers all cylinders
• Not CARB legal

Features

• Wiseco Sport Compact series -- dedicated forgings for lightweight, high-strength performance
• 2618 aluminum alloy -- higher tensile strength for boosted applications
• ArmorGlide skirt coating -- friction reduction, seizure resistance
• -7cc dish crown -- 9.6:1 compression ratio, suitable for forced induction
• Specially designed valve pockets -- maximum flow around intake and exhaust valves
• Steel nitride/Napier rings -- superior ring seal and oil control
• Precision ring grooves -- minimize blow-by and oil consumption
• Complex skirt profile -- reduces friction, promotes bore stability for optimum ring seal
• Engineered, forged, and machined in the USA

Specifications

• Series: Sport Compact (AP)
• Bore diameter: 81.00mm (3.189")
• Bore oversize: Standard
• Compression ratio: 9.6:1
• Piston volume: -7cc (dish)
• Compression height: 32.71mm (1.288")
• Stroke: 86.4mm (3.402")
• Rod length: 144mm (5.669")
• Wrist pin diameter: 20mm (0.787")
• Wrist pin length: 2.500"
• Wrist pin part number: S623
• Material: 2618 aluminum
• Skirt coating: ArmorGlide
• Quantity: 4 pistons
• Rings included: Yes (steel nitride/Napier)
• Wrist pins included: Yes
• Locks/clips included: Yes

Included Components

• 4x Wiseco forged pistons (81.00mm)
• 4x Ring sets (steel nitride/Napier)
• 4x 20mm wrist pins (S623)
• Wrist pin locks/clips

Product Description

The Wiseco K563M81AP is a Sport Compact series set of four forged pistons for the 1998-1999 VW/Audi 1.8T 20V engine at standard 81.00mm bore. This application is strictly year-specific -- 2000 and later 1.8T 20V engines transitioned to 19mm wrist pins and require a different piston; the K563M81AP is for 1998-1999 engines only using the 20mm wrist pin (engine codes AVC, ANB, AWU, AEB, APP, ARY, AUQ). At -7cc dish and 9.6:1 compression ratio, this piston is designed for forced induction builds where lower compression is needed to manage boost pressure safely.

The Sport Compact series uses dedicated Wiseco forgings in 2618 aluminum, producing a lightweight piston with the tensile strength required for turbocharged applications. ArmorGlide skirt coating reduces friction during break-in and long-term operation. Specially designed valve pockets provide clearance for the 1.8T 20V's five-valve-per-cylinder head. Ships complete with rings, pins, and clips. Piston-to-valve clearance must be verified during assembly. Engineered, forged, and machined in the USA.