Ever since the invention of this reliable workhorse of the automotive world, the quest for increasing the efficiency of an internal combustion engine has been going on. In recent times, much attention has been focused on achieving this goal by reducing energy lost to the coolant during the power stroke of the cycle. A cursory look at the internal combustion engine heat balance indicates that the input energy is divided into roughly three equal parts: energy converted to useful work, energy transferred to coolant and energy lost to exhaust. The reduction in, or the elimination of, in-cylinder heat transfer to either the coolant and/or the environment does not violate the second law of thermodynamics and, moreover, according to the first law, has the potential of producing more work. Added to this, another important advantage of the concept is the great reduction in parasitic losses due to elimination of cooling system, thus increasing the brake horsepower of the engine. The main purpose of this study is to evaluate the heat losses at different engine loads and speeds with and without ceramic-coated diesel engine. The results showed a reduction in heat losses to the coolant and an increase in exhaust energy at all load levels. (C) 2003 Elsevier Science B.V. All rights reserved.