Whats the highest revving engine?

Question

how fast does the fastest revving engine in the world turn in RPM?? not the tiny matchstick size gas powered turbine at 500,000 but a real combustion engine if you know what I mean.

Answer 1

NASCAR SPRINT CUP ENGINES routinely turn 8,000 to 9,500 RPM at 352 cubic inches I think thats turnin' pretty quick.

Answer 2

Indy car motors turn ~18000 rpm

Answer 3

formula one  V10 engines were turning 21000RPM before the rules were changed, introducing a 19000RPM rev limit.