ENgine overheat

[Luno13]

What is your power setting? Prop pitch? Radiator?

If you're cruising, you don't need to fly at full power. It depends on the situation, but around 50% power makes a good "economy" cruise, and 70% for "combat" cruise.

When diving, reduce power and prop-pitch. You don't need 100% prop pitch all the time in combat either. A coarse pitch will actually get you a higher top speed, although with slower acceleration. Fine pitch (100%) is used for climbing or quick acceleration.

With these tips you should be fine. Of course, open the radiator if you must, but it will degrade performance.