[spunkets]

"However, nitromethane has been described as "the simplest nitrogen-based high explosive" -

It's not an explosive at all. It's a very high octane fuel that contains some oxidant. The model airplane engine is a diesel. This fuel just allows the engine to work w/o being sensitive to F/A ratio.

[ItsTheMediaStupid]

spunkets,
Nitro is about the lowest octane fuel I can think of. In racing engines detonation (not the explosion type)is a big problem when using 100% racing nitro. It is cured with very low compression ratios (I think some are below 5:1 now), and very rich mixtures. The fuel air mixtures are now so high that a restriction of the air flow can cause it to richen up enough to ruin the engine with hydralic lock. That is where there is so much unvaporized fuel that it's volume is smaller than the comubstion chamber. Since liquid is relatively uncompressable this will break the pistons, rods, and head.