OK,a lot of people say when you modify an engine,more cam, compression overbore,etc,it can run hotter and maybe require an upgraded cooling system. I can't understand that,but here's what I dont understand;The engine running along at part throttle,like 90 percent of the time on the street,is probably making less than 30 hp.So you increase the cooling load with HP modifications and the same engine is now making more or less the same power to push the car along at legal speeds.It's obivious if you're running the engine wide open,the increased power makes more heat.So why does it run hotter at part throttle?? Are cooling systems that marginal? My own observations with a modified 261 Chevy and a 302 GMC engine that the increased compression and more spark advance did not make the engine run hotter.In some situations it ran cooler!!!
Spark advance makes little difference. A lean condition inside the combustion chamber will make a catastrophic difference. Try this for some answers.... Billavista on cooling.
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