SBF F/T Piston Set 4.040 Bore -6.5cc

The KB PERFORMANCE PISTONS SBF F/T Piston Set 4.040 Bore -6.5cc is a hypereutectic piston set engineered for Small Block Ford applications demanding precision compression geometry and reliable high-RPM durability. This eight-piece set delivers consistent bore fit and controlled combustion chamber volume across all cylinders, making it a core rebuild component for stroker builds, racing engines, and stock-displacement performance applications where accurate compression ratios and long-term reliability are non-negotiable.

Each piston features the 4.040-inch bore specification with hypereutectic construction—a silicon-infused aluminum alloy that resists thermal distortion and reduces skirt wear under sustained high-load operation. The -6.5 cubic centimeter dome creates a compression cavity that allows builders to fine-tune effective compression ratios without oversized cylinder heads. Ring grooves are sized to 5/64 x 5/64 x 3/16 inches, accommodating standard Small Block Ford ring packages and ensuring consistent sealing pressure across the stroke. This specification baseline applies across all eight pistons in the set, eliminating the variance problems sometimes encountered with older or lower-tolerance piston sources.

Small Block Ford engine builders—whether assembling a daily-driver stroker, vintage hot rod, or competition platform—rely on KB Performance for repeatable bore geometry and material consistency. The hypereutectic alloy maintains dimensional stability through thermal cycling, critical for engines that see both highway cruising and wide-open-throttle pulls. Builders selecting the 4.040 bore and -6.5cc compression chamber typically pair these pistons with matching wrist pins, connecting rods, and ring sets to ensure complete bottom-end balance and optimize compression ratios for their specific fuel and ignition timing strategy.