Dick,
Apart from the "klompen" that I used to wear as a kid, it is very important to look at the fact that the engines have no time to run hot in this contest. You could run them previously with sufficient oil, and during the contest with no oil at all for all out power, and get away with it. Drag racers seem to do it all the time. In some of the videos, you see a lot of oil smoke, even though I know that my customer (poppeye) runs at only 10% oil. The engines would barely survive this in normal flight practice, yet they have no problems or even the slightest carbon from this kind of " abuse " . After a season, the engines look like new! An eye opener for sure, which makes me remind a supertigre that I prepared for UC flight with a soft iron Dykes ring. The engine laster forever until I decided to use it for RC. 5 tankfuls did the trick in relaxing and wearing down that ring to usefulness. It just goes to show how different operating conditions can lead to different design requirements, especially if the engine never sees more than about five seconds of all-out power!