Maximum Continuous Cruise

[MTRBTR]

So in the owners manual for PCMs and on the engine covers there is a Max RPM and an "Max continuous cruise. "
What does exactly "Maximum Continous Cruise" mean? How long of a period can you operate your engine above "max continuous cruse" and not damage your engine?
For example, my owners manual states 4000 RPM max continuous cruise. I like to slalom and everyone else likes to surf. If I prop the boat so that I am running slalom speeds at 4300-4400 RPMs is that bad for my engine? I have never heard a good answer as to how long you can be over maximum cruise RPMS.

[functionoverfashion]

I suspect for the amount of time you're actually running slalom speeds, it's totally fine. I also doubt you'll find a definitive answer on this question, but it's still a good one.

I don't have any science to back this up, but it feels like running under heavy load, e.g. surf speeds with ballast, would be harder on the engine in the long term than running high RPM for a few minutes a day.

Here's an anecdote to back up my totally unscientific opinion - on my old Supra, the engine we had in it was a GT-40 with unknown history other than an overheat severe enough to melt the plastic engine cover a little. It ran great all the time but always had a little knock that got better as the engine warmed up, but never went away completely. We ran it for hundreds of hours like this over 4 years. One day we decided to basically sink the boat to try to make a big surf wake (it had a decent surf wake with the right balance of people and ballast already). It was way overloaded but tried its best to get up and go. Suddenly, we noticed the knocking got quite a bit louder. We idled back to the dock, but it was unmistakable. It was the straw that broke the camel's back, and we opened the engine up to find a scored cylinder. This could have been happening before, but it was undoubtedly exacerbated by the heavy load. We used to run it flat out from time to time (~4,700rpm) and never noticed any difference, until that day.

Uhh, what were we talking about? Oh yeah - don't lose sleep over occasional slalom runs so long as you're not bouncing off the rev limiter. That's my two cents and then some.

[MTRBTR]

Thanks FOF. That is my thought is that I don’t run it that hard for very long. But this boat needs to last a long time for me.