Happy New Year 2010 everyone, I need your help with the determination of heat rejection to coolant from engine. I need to define this in order to finalise the geometry of a suitable radiator. I have an Excel spreadsheet from my team mate about the results obtained at the lab last year. I believe the lab was to determine the heat rejection from the engine to coolant by measuring in and out temperatures of coolant (100% water) and plug those in a well known expression Q = m X c X delta(T) Here is the description from the guy from last year. "The data for heat rejection calculations was acquired during the engine testing at Tickford. Temperature and pressure data of the coolant was collected against engine speed. A Grundfos water pump was used during testing, supplying coolant at a constant rate of 0.9 kg/s. The coolant is 100% water. This data was used to calculate heat rejection to the coolant against engine speed using Equation 7 1. The heat exchanger used during the test was a water to water module with flow rate controls on the cool water side. These were set such that the coolant into the engine after warm up was at 700C." I then plotted the graphs comparing the heat (from calculation) to the developed power by engine. A bizzarre result arisen - the heat to coolant is a lot greater than engine power, not equal to engine power according to rule of thumb saying 33% of total energy from fuel is equally converted to driving power and heat rejection to cooling system. Can anyone suggest what happens? Was there something wrong? What should I do next? Should I stick with a more good-looking, but unusual result from the experiment or rely on the less-academic conventional rule of thumb which take the heat as equal (or 70% suggested by some rad manufacturers) of the engine power? If I went for the experimental one, I would end up having so much bigger rad (around 80 kW from graph), opposing to everyone's expectation as they think the current rad is too big. We did have an overheating issue between the competition last year which I think was caused by too small rad. The current rad is design for dissipating only 37 kW of heat. Can anybody reckon me some other more accurate method on determining the desire heat rejection rate of a new radiator? Thank you very much in advance.