The shit has been beaten out of my motor for over 100K miles and its still running strong, even if it is ailing a bit.

A sturdy motor that is not putting out more than double its stock horsepower should be able to last longer than 100K miles.

Motors are usually only built with a safety factor of 4 so people that are pushing their engines for 3 or 4 times the stock power ratings are really pushing their luck and are gambling with their engines future.