HKS 21003-AH001 Forged Piston Kit - L15A/LEA D73

The HKS 21003-AH001 is a forged aluminum piston kit engineered for the Honda L15A/LEA engine with a standard 73mm bore diameter. Designed as a high-performance upgrade over factory components, this kit delivers exceptional strength and durability for modified or high-output engine builds.

Key Features:

• High-strength forged aluminum construction — 186% stronger than stock factory pistons
• Standard bore size: 73mm with 80mm outer diameter and 60mm compression height
• Piston pin bore accepts 18mm semi-floating wrist pins (Honda factory pins required)
• Nickel-plated piston surfaces and top ring lands for superior resistance to abnormal combustion damage
• Compatible with HKS Head Gasket for adjusted compression ratio tuning (8.4:1 with 1.2mm gasket; 8.7:1 with 0.8mm gasket)
• Factory piston rings required separately
• Not CARB legal — not for sale or use in California

HKS connecting rods for the L15A/LEA engine (sold separately) are engineered to pair directly with this piston kit, using M8x1.0 connecting rod bolts for enhanced rigidity and semi-floating small-end pin interface. Together, the piston and rod combination is optimized for improved throttle response and sustained high-performance output.

HKS is a globally recognized leader in aftermarket performance engineering, founded in 1973 and trusted by professional tuners and enthusiasts worldwide. All HKS internal engine components are precision-manufactured to ensure reliable fitment and consistent power gains.