racing engines are not designed to go 50k miles, let alone over 100k, so sometimes things that are applicable for them would suck on a street car. most race engines are built with much looser tolerances to create less rotational drag, but they know that it'll be torn down & rebuilt every so often... many race motors don't survive 1k miles even without being torn down, except road racers I guess, but even so, 10k miles would be way past there servicable life in most cases...
