On Thu, 12 Oct 2017 17:47:17 -0400, "Mr. Luddite"
wrote:

On 10/12/2017 5:12 PM, wrote:



I don't think you can compare the wear and tear of say, a GM 350 V8 used
in a car with the marine version of the same engine. Unless you are
just trolling around all the time, the marine engine is working at or
near full load and at relatively high RPM compared to the car version.
The car version, cruising down the highway with the torque converter
locked up is only turning about 1600 -1800 RPM at 60-65 mph and is only
developing maybe 20 or 30 hp to do it.


You never rode around with me in my Corvette I suppose. That was
before the Maryland cops figured there was money in speeders and there
was virtually no speed limit on the beltway after dark.
I have made lots of trips at or near WOT(140 mph or so)
I also ran it pretty hard all the time.

My Chevelle had a 456 rear so 70 MPH was around 4500 RPM
The Corvette was a 336 so it was a bit lower at 70.
My Honda is turning ~4k on the interstate (75-80). The V-tech kicks in
at 5000 RPM and I feel it a lot, just running up and down US41.

My boat certainly has an easier time of it.
Engine sp Time[h]
- 1000 r/m 125
1000 - 2000 822.9
2000 - 3000 101.7
3000 - 4000 175.4
4000 - 5000 51.1
5000 - 6000 0.4
6000 - 7000 0
Engine ho 1276


High RPM for engines designed for them doesn't hurt but "lugging" them
sure is.

Running a boat is closer to continuously lugging the engine for hours on
end if cruising somewhere. That's where the diesels have the big
advantage. They are made for it.

BTW ... your Honda is turning 4k RPM at 75 to 80? That seems very high.
Once the torque converter locks up (assuming your Honda is an auto and
has one) cars today usually are running closer to 2K or maybe a little
more at that speed. That's my experience anyway. The new Canyon I
bought has an eight speed transmission and a lock up TC. At 65 mph I am
turning about 1800 RPM.

Dunno about the Honda but that was what I remember, though it might be
more like 80-85. We go fast down here. Next time I am out I will look.
It is a 5 speed and I am talking about 5th gear.

If your boat motor is "lugging" you have the wrong prop. Outboards
should still suffer from the same problems tho and the commercial guy
here gets 6000 hours or more out of his 175 Zekes. (Single, pushing a
38 foot pontoon)
I will admit he understands protecting his equipment and he is not
running WOT all the time, neither do most of the people I know.
Assuming the technology of Japanese outboards is similar to the cars,
they do redline them a lot lower tho.
My F70 redlines at 6300, enforced by the ECU and the Prelude is more
like 7400, not enforced by anything. but a red line on the tach