Carver 356 - Running 8.1's at 3600rpm

Humbucker427

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One of the boats I'm interested in is the 2001 Carver 356 with 8.1's. I have a performance/spec sheet on this boat sent to me by a member of this forum that shows some interesting figures for this particular days testing.

At 3000 rpm, it ran 18.7 mph, at .73 miles per gallon
At 3200 rpm, it ran 20.9 mph, at .73 miles per gallon
At 3400 rpm, it ran 23.4 mph, at .74 miles per gallon
At 3600 rpm, it ran 25.9 mph, at .98 miles per gallon

With WOT at 4495, that gives us a cruise speed of 3600 RPM (using the 80% rule).

My question is this: What kind of trade off is there to running the "recommended" 3600 rpm? Are we looking at a significant loss in the lifespan of the engines, or are they designed to run at 3600 rpm just as well as 3200 rpm? Maybe it's just me, but having worked on several large block automotive engines, 3600 rpm seems high for a couple large block 496's to run all day long. ???

Anyone have an opinion on the matter? Thanks!
 
the 8.1 is cammed to run at 5000 WOT. As such, the cruising RPM is 3600 to 3800 RPM. We have been telling our customers this for a few years now, and have had no failures to date
 
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