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any increase in speed (rotational) directly translates into an increase in linear distance travelled (for the internal engine components).
on an engine that would be considered worn out at 100k miles (30 year old + large displacement domestic engines), a large increase in rpm would adversly affect durability. Those engines were designed to operate at around 2000rpm continuous duty cycle.
on an engine that regularly goes as much as 500k miles without failing, and was designed to run around 3500 rpm continuous duty cycle, the rpm increase is not as significant.
basically, you need to carefully consider what engine you're speaking of. generalizations cannot be made about wear vs rpm.
you also need to consider what conditions constitute a high wear environment. most internal combustion engines do very well in a steady state rpm operation. optimal oil pressure, optimal temperature, low changes in load. Stop and go traffic at low rpm, high load and unstable temps will kill an engine twice as fast. SAE (Society of Automotive Engineers) has done extensive research on the topic. generator power plants (stationary engines) are often torn down and inspected at 10,000 hours of operation, generators typically run at a steady 3600 rpm (divide by 60 to 60Hz, AC voltage frequency), which equates to 60,000 miles. If properly maintained, these units show no wear for 20k-30k hours, or 120k - 180k miles. Again, this is at a constant 3600 rpm. This bears out against some of my former customers' vehicles. I've serviced commuter taxis (typically highway mileage, airport shuttles, etc), and have regularly seen them in service for 300k-400k miles, with no engine concerns. Contrastingly, I've had city taxis (same vehicles, Crown Vics, Explorers, Windstars) that don't survive 100k miles on one engine, due to the extreme loads placed on the engine by extended idling, high load-low rpm conditions in which they are operated.
To sum up, I'd run a Festy engine at 5000rpm 24hrs a day without worry, as long as I change the oil, coolant, thermostat, and check acc'y belt tension on a regular basis.
on an engine that would be considered worn out at 100k miles (30 year old + large displacement domestic engines), a large increase in rpm would adversly affect durability. Those engines were designed to operate at around 2000rpm continuous duty cycle.
on an engine that regularly goes as much as 500k miles without failing, and was designed to run around 3500 rpm continuous duty cycle, the rpm increase is not as significant.
basically, you need to carefully consider what engine you're speaking of. generalizations cannot be made about wear vs rpm.
you also need to consider what conditions constitute a high wear environment. most internal combustion engines do very well in a steady state rpm operation. optimal oil pressure, optimal temperature, low changes in load. Stop and go traffic at low rpm, high load and unstable temps will kill an engine twice as fast. SAE (Society of Automotive Engineers) has done extensive research on the topic. generator power plants (stationary engines) are often torn down and inspected at 10,000 hours of operation, generators typically run at a steady 3600 rpm (divide by 60 to 60Hz, AC voltage frequency), which equates to 60,000 miles. If properly maintained, these units show no wear for 20k-30k hours, or 120k - 180k miles. Again, this is at a constant 3600 rpm. This bears out against some of my former customers' vehicles. I've serviced commuter taxis (typically highway mileage, airport shuttles, etc), and have regularly seen them in service for 300k-400k miles, with no engine concerns. Contrastingly, I've had city taxis (same vehicles, Crown Vics, Explorers, Windstars) that don't survive 100k miles on one engine, due to the extreme loads placed on the engine by extended idling, high load-low rpm conditions in which they are operated.
To sum up, I'd run a Festy engine at 5000rpm 24hrs a day without worry, as long as I change the oil, coolant, thermostat, and check acc'y belt tension on a regular basis.
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