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In this work, the progressive disassembly method is used to determine the mechanical losses contributed by the different components of a single-cylinder spark ignition engine tested at crankshaft angular speeds of 300−1900 min-1, and lubricant temperatures between 30−35 °C. From the experimental measurements, the losses due to the intake and exhaust manifolds, cylinder head, valve train, camshaft bearings, connecting rod-piston assembly, flywheel, and crankshaft bearings are determined. It is obtained that the elements with the highest contribution are the piston-connecting rod assembly and the cylinder head with contributions of 19.2−36.9% and 27−33.3%, respectively. Additionally, the indicated diagram method is applied to assess the pumping, heat, and blow-by losses of the complete motored engine during the intake and exhaust processes. Pumping losses, heat and blow-by transfers, friction, and auxiliary losses are characterized, obtaining contributions between 5.8−14.7%, 14.8−37.9%, 46.4−64.6%, and 5.8−9.9% for each group of component losses, respectively.
Romero et al. (Thu,) studied this question.