Originally Posted by Cubdriver

The TBO figure for most Lycos and Cont's is a recommended figure and is not actually a mandated overhaul time. Many of these engines have not been overhauled for several multiples of their TBO times. I do not agree with it as a practice, just to point out that the engines themselves can go the distance.

If you assume a 30 miles per hour average speed for the average car engine, then it goes about 60,000 miles in 2,000 hours. If it lasts for say, 120,000 miles or 4,000 operating hours, this equals two TBO-periods for an aircraft engine of the same sort. The latter are often still found in service, with regular overhauls of course, after as many as 6 TBO cycles. I get this number by dividing a hypopthetical piston airplane with 12,000 hours on it by 2,000 hours. Lots of these airplanes exist and many have the original engines.