There are several old airplanes flying today (Doc and FiFi, The SuperConnie and numerous B-17/24/25's) that can't fly above about 12,0000 feet because above that altitude they need boost on the engines and with "just 100-octane" fuel, they detonate and gag.

Although I don't understand the complete octane rating, WWII AvGas and fuel for the last generation of radial engine aircraft was rated as 113/130 octane. They were called "aromatic fuels" because the molecular structure looked more like perfume than conventional fuels.