My grand prix went 280,000kms before i traded it and i never changed a water pump or the timing chain/dampers ect. Sometimes you get lucky. Other times you maintain your stuff and it lasts forever. But theres nothing to maintain on a nitro engine. Its not like you have to keep up with oil changes and topping up coolant, your basically gambling with your money every time you fire up a nitro engine. All you can do is keep your air filters changed and oiled properly and hope the guy who built your motor wasnt still hung over when he got to work on monday. Id like to think you get what you pay for but that doesnt seem to be the case all the time.
I realize the forces at work in these motors but theres gotta be something companies can do to boost reliability a bit.

Top fuel engines are a little different than rc engine too btw. A top fuel engine makes 8000+ hp running 98% or more nitro. We run 20-30 for the most part and the methanol stabilizes it. Im not sure you could even get 98-100% nitro to light in our engines. Top fuel engines run twin magneto ignitions with sparkplugs. Although by the 60' mark the plug is burnt out and the motor is dieseling the same way our engines do, but it takes spark to initally fire the motor up. Those motors also come close to 20,000rpm near the end of a run with a ton more stroke, even in scale, than an rc engine. I would say in comparison a top fuel motor has way higher forces to deal with. Also, the engine internals get tested and re-used. Not that weekend obviously but you dont throw away a $3-4000 set of conrods after one use. Bearings yes, but bearings arent that expensive. No reason to toss something that can be rebuilt good as new with a $10 bearing.

Our engines should have replacable bearings for the conrod. That would make things a bit cheaper. Youd have to press them in for sure but a tool could be made so that anyone could replace thier own. I dunno, id just like to run a motor for a few gallons and not have to rebuildit twice. Call me crazy lol