Evaluation of the accuracy and reliability of the acceptance test results for ZMZ engines

The accuracy and reliability of measurement results for controlled parameters are essential for ensuring the quality of engine repairs. However, current standards, such as GOST 10448-2014 (“Piston Internal Combustion Engines”) and GOST 14846-2020 (“Automobile Engines: Bench Test Methods”), do not specify requirements for the permissible error in the indirect measurement of engine power. This study aims to develop metrological recommendations to achieve specified levels of reliability for measurement data obtained during the acceptance testing of repaired engines. Using probability theory, the authors derived a formula to calculate power measurement errors and established permissible error limits for various ZMZ engine models. A comparative analysis was performed to compare these calculated limits with the actual errors observed during running-in tests on GOSNITI test benches (models KI-5274, KI-5540М, KI-5541М, KI-542М, and KI-2118А). The results indicate that the actual measurement errors remain within the calculated permissible range (derived from the GOST-based methodology). To enhance the reliability of power control, the authors developed recommendations for calculating acceptance limits with an offset relative to the nominal power value. Permissible error margins and acceptance limits were determined for various ZMZ engine models based on the required reliability levels. The application of this methodology will improve measurement quality and the overall reliability of control results during the acceptance testing of repaired engines.