Coolant subcooled boiling in the cylinder head regions of heavy-duty vehicle engines is unavoidable at high thermal loads due to high metal temperatures. However, theoretical and experimental studies of coolant boiling under these specific application conditions are generally lacking. In the present study, subcooled flow boiling heat transfer experiments were performed with water and ethylene glycol/water mixtures at volume ratios of 40/60 and 50/50 in turbulent flow in a specifically designed and fabricated test facility with its experimental test section simulating the heating conditions of the coolant channels in the cylinder head regions of heavy-duty vehicle engines. Boiling curves and subcooled flow boiling heat transfer coefficients for the tested fluids were determined based on the experimental results. Comparisons between the experimental data and the predicted values from existing correlation equations in the engineering literature are presented. (c) 2014 Kenworth Truck Company, DAF Trucks and Elsevier Ltd. All rights reserved.