Within a matter of 2 weeks of flying SSC I came up with 2 engines that hit hard enough to crack the crankcases where the cylinder meets the bottom end. That just demonstrates that there is too much kinetic energy in the event by design.
It is a very popular event, so I'm not trash talking it, just relaying my experience with it.
I fly .15 sized combat with PAW diesels on "retired" C/L combat foamies. The power is 11-12,000 rpm with 8x5 props and they look like they are going 35 mph in a dive. They pack enough wallop to knock into each other and take out an elevon....but they fly so slowly that you can break off your attack if the timing doesn't look right. The only diesel planes that I retired to the burn barrel are the ones that are too funky to mess with.
Diesel has it's drawbacks with the smell, fuel creep, availability, etc., but it is fun to see a couple of low rpm chuggers out there trying to score.