There are many misconceptions, for one it’s more common than you think for a major engine manufacturer of large Agricultural / Commercial
engines to ensure that wide open, isn’t really wide open. Derating a motor
leads to a long life and that leads to a good reputation.
They are very often derated and this is done to ensure long life, remove or defeat the governor and they are capable of much more power.
To see motors that are often run hard, look at the big Sportfishing crowd, I mean the big boats that are often run at 200 “off the top” or so, and ask how long they go between overhauls.
Ask the guys with the big turbo DD’s how long they last, where a NA DD if not run too hard will last nearly forever, literally.
I used to run into this line of reasoning all the time with customers and turbine engines, they would say it’s rated for continuous operation at 101% NG and xxxx C temp, why shouldn’t I run it at those numbers, well the reason is it will shorten the engines life is why, sure do it, but your going to pay a lot more at TBO time.
The argument of generators running wide open all the time is a little incorrect, they usually run either 1500 or 1800 RPM, and that’s not often wide open on a motor
that is in other uses rated for much higher RPM, their really isn’t small special generator
motors, they are simply off the shelf little motors selected for their output power at 1500 or 1800 RPM, and yes look at how long they last, they often last a very long time.
Now great big huge power station generators may well have special motors, but not smaller ones.
For sake of argument how long does a high speed 3000 or 3600 RPM generator lasts as compared to a 1500 or 1800 one, I don’t think anyone will tell you the higher RPM ones last longer.
Wear goes up as a factor of the energy in the rotating components, and RPM increases the energy greatly.
Structurally RPM isn’t the limiting factor, rotating assemblies are capable of insane RPM’s, it’s actually piston speed, a short stroke motor can turn much higher RPM than a long stroke one.
It’s not that Diesels like to be run hard, it’s that very often due to their low RPM and power output per cu in compared to say a car motor, they will tolerate being run near max output better, because max isn’t really usually all that high.
Run one pretty hard in surges if you will to break it in, be sure to run it real hard more and more often as it accumulates hours, and then once your certain the rings have seated, then you can baby it for a good long life. Don’t start out babying a brand new motor, you need to run it hard enough to seat the rings first. It’s cylinder pressure that forces the rings against the cylinder walls that seats the rings, and that pressure comes from a lot of fuel being burned and driving the pressures up as a factor of heat.
Engines are not powered by explosions, they are powered by the rapid expansion of air from the temp of fuel burning, explosions are called detonation, which will quickly destroy an engine.
But also wake one up gently, allow it to warm up slowly and once the oil temp is up, then you can throw the power to it if you like, and also allow it to cool down slowly before shutdown to prevent heat soaking, especially in a turbo motor.
But the normal way most all of us operate our boats is near perfect, most of us crank our motors up in neutral and bump the RPM to about 1000 or so and then go about getting the anchor
up and stowed. That is a near perfect warm up in my opinion, then we usually go slow approaching an anchorage, stop, drop anchor
and back down on it and leave the motor idling until we have the snubber set, and that’s about a perfect cool down, again in my opinion.