Water jackets for both cylinder head and block have been designed scientifically to accomodate precision cooling using longitudinal flow. The cylinder head water jacket was made from a rigid single piece sand core. The water jacket volumes in the cylinder head and block were only 46% of that compared to a conventionally cooled engine of similar swept volume.Test results showed that an engine employing precision cooling warmed up 18% quicker than an engine of similar geometry using conventional cooling. Another observation was that the peak and overall distributions of metal temperature in both the cylinder head and block were lower without adverse effects on HC emissions and motored friction. Further benefits of the precision cooled technique were a reduction to water pump power (up to 1.85 kW) due to lower bulk flow rate of coolant and a reduction of heat to coolant of 4.5% (based on percentage of fuel heat).