I just ran some numbers on the '86 RX7 I've been driving for the past couple of years.  I know this is mostly speculation, and that driving conditions don't equal continuous hi-power operation... my personal opinion is that start and stop driving in the city is much harder on the engine than setting it at some constant power setting and just letting it go.  Anyway, the car has about 210,000 miles on it.  I assumed 25% city miles at 35mph, 25% secondary road driving at an avg of 50mph, and 50% interstate driving at 65mph.  Running the numbers tells me that this engine has almost 4200 hours on it.  This works out to over 650 million e-shaft revolutions since day one (yikes!).  Simple division says that if this same engine was in an airplane and run at an average 5300rpm it'd have an equivalent 1900 hours on it.  It's still running strong.  I know, everything isn't equal here and there are other considerations when running at the higher power settings required in the aviation environment.  Given all the above, I have been and still am totally convinced that a normally-aspirated (or turbo-normalized) 13B in an airplane will easily give 2000 hours TBO.  Just my opinion.

        <Marv>