Radiotracer method for measuring real-time piston-ring and cylinder-bore wear in spark-ignition engines

A radiotracer method was developed to measure wear rates of piston rings and cylinder bores in spark-ignition (SI) engines. Piston rings were made radioactive by neutron activation and blocks were activated by surface layer activation. With this radiotracer system, top compression ring wear can be determined to better than ±5 μg/h and cylinder-bore wear can be determined to better than ±1 nm/h simultaneously in a 1 h measurement period. This sensitivity is superior to any other real-time wear measurement system currently available. High-sensitivity wear data is necessary to develop engine hardware and lubrication systems that will prevent excessive wear over the life of the engine. Details of the design and operation of the wear measurement system are presented as well as representative data on a production V6 SI engine.