Why 20,000 RPM is the limit for cars
Why doesn't a regular piston engine spin up to 20,000 rpm? A piston weighing 500 g experiences an overload of almost 47 kN, changing direction 667 times per second. The valves don't have time to close, and the 95 gasoline simply doesn't have time to burn. Formula engines get around this with a short stroke, air springs, and special fuel. Aircraft model engines on methanol and nitromethane spin up to 35,000 rpm - small masses and fast fuel work wonders!