A piston ring is made from a copper-nickel-silicon-chromium alloy. This material permits the top compression ring of a piston to be moved closer to the piston crown, reducing crevice volume and reducing the tendency for pre-ignition. Ignition timing advance can be realized by installing the rings and letting the ECU advance the timing as the sensors allow, increasing efficiency. Also, shorter pistons and longer connecting rods are possible. The shorter pistons reduces the reciprocated mass in the engine and the longer connecting rods reduce the frictional loss caused by radial forces pushing the piston against the liner. Both reducing volume and tendency for pre-ignition increase engine efficiency.