Pistons are forged in A2618 aluminum alloy as in the 3V-S, which is what the engineers call the RC213V-S, and they are oil-cooled by a new system that serves two goals. Remember back when AMA Supersport privateers increased oil-pump internal clearance, claiming this saved power? For this same reason, some F1 and production-car engines have two-speed or variable-speed oil pumps, a high ratio for lower revs and a lower one for higher rpm, to prevent power loss from delivering too much oil. In this RR-R engine, Honda uses the piston-cooling oil system to achieve the same effect. At lower revs, when piston oil cooling is not needed, a spring-loaded ball valve closes, sending all the oil to bearings. As the engine revs up and oil pressure rises, the ball valve opens, delivering the excess oil being pumped to the piston cooling jets. Instead of providing a single jet to each piston, this system sprays in multiple directions to achieve more comprehensive piston cooling.