Wiseco Acura K20 K24 FLAT TOP 1.181X86.5MM Piston Shelf Stock Kit - K631M865

Wiseco Forged Piston Set — Honda K20/K24 86.5mm Flat Top (K631M865)

A 2618 forged flat-top set at 86.5mm — a half-millimeter over stock, so this is the right choice when the block needs boring anyway. Forged from 2618 aerospace alloy for tensile strength and resilience under extreme RPM and high-stress conditions, and machined in the USA.

Crown thickness and ring lands are designed for power-adders — turbos, blowers, nitrous. That's the distinction that matters on a boosted K: the top land and crown are where a piston fails under detonation, and this set is built with that in mind rather than adapted from an NA design.

ArmorGlide skirt coating comes standard, reducing friction, resisting seizure, and quieting the engine on cold start. Strutted forging adds strength through the pin boss area.

Specs: 86.5mm bore (3.405"), 30.00mm compression height (1.181"), flat top with valve reliefs, -3.4cc volume, 22mm floating wrist pin. Sized for 86mm stroke with a 139mm rod. Roughly 9.6:1 in a stock-deck K20.

Complete ring set included.

Fitment: Honda/Acura K20A, K20A2, K20Z, and K24 blocks running a K20 head. 02-06 RSX Type-S, Civic Si, and K-swap builds.

Verify your compression before ordering. The ratio depends on head gasket thickness, chamber volume, and deck height — head work moves the number. And this is a 0.5mm overbore, so the block needs machining to suit.

Set of 4 pistons with pins, locks, and rings.