Agree with foxmoth, maybe not right forum. But for example....
Lycoming O-235 (Tomahawk) 2400 hours or 12 years. Extendable subject to inspection by 20% (2880 or 14.4 years)
Continental O-200 1800 hours or 12 years, hence 2160 hour/14.4 years 'on condition'
Gypsy Major 1500 hours, but no calendar life limit - yahoo
I had an O-235 that went to 2876 hours, and was a 'better' engine at that age than the (zero-time) one which replaced it