There are two strategies for keeping cylinders cool in cruise: push the red mixture knob forward for a rich fuel/air mixture setting that uses unburned fuel to lower cylinder head temperatures, or pull the mixture knob out to such a lean setting that an abundance of air and reduction in engine power and heat cools the cylinders. Running aircraft engines “lean of peak” (LOP) typically reduces airspeed about 5 percent in cruise while lowering fuel consumption about 20 percent—but not all engines are capable of LOP operations, and doing it wrong can cause permanent and costly engine damage.
What equipment does your engine need to run safely lean of peak? It must be fuel injected (not carbureted), preferably with matched-flow nozzles such as GAMI injectors, and it should have a graphical engine monitor with cylinder head temperature (CHT) and exhaust gas temperature (EGT) probes on every cylinder. Electronic ignition systems are more efficient than magnetos and simplify LOP operations, but electronic ignitions aren’t required.