i guess it comes down to what your definition of running for 20k hours really is?
mine would be any engine that can make 20k hours with only minor rebuilds, such as new rod brg,
rings, and valve jobs as needed.
but then again, with plain upper brgs w/hollow dippers, a good clean bore and good rings couple with a good
airfiltration unit and well filtered fuel, and a decent 3 angle or at least a two angle with in included relief angle of perhaps
a half degree,, i would expect the engine to be relatively trouble free over the course of 20k hours...
oh yes, we probably would need to change out the idler gear on a periodic basis, just as standard operating procedure.
there are numerous folks out there with upwards of 20k hours and having had no catastrophic failures.
thats not bad in my opinion.
don't get me wrong, i am no fan of a lister/oid, but they aren't that bad in most cases
they just need some care in build and ongoing maintenance.
for a basic long life engine, the c201 thermoking/isuzu is about as bullet proof an engine that was ever made
in the 23-26hp range, those things will literally run forever... 100k miles probably not, but i am sure they will
make 20k hours with some maintenance, and over 40k hours with good maintenance.
and now i am wondering about the little cat/perkins 2 cylinder engine's, they claim 6k hours
but i wouldn't be surprised to see one run well over 10k hours in generator operation where maintenance is
good and where they are not out in the dirt trenching or whatever but in a genshed that is fairly clean.
bob g