BoatBanter.com - Yanmar Offers a Turbo Diesel Outboard

On 10/12/2017 5:12 PM, wrote:
On Thu, 12 Oct 2017 16:22:23 -0400, "Mr. Luddite"
wrote:

On 10/12/2017 4:03 PM, wrote:
On Thu, 12 Oct 2017 13:11:11 -0400, "Mr. Luddite"
wrote:

On 10/12/2017 1:05 PM, wrote:
On Thu, 12 Oct 2017 10:52:37 -0400, "Mr. Luddite"
wrote:

THere's something about gas engines running for hours at 3,600 to 4,000
RPM that disturbs me, even though I realize they have cams, etc., that
are designed for it. Seem to remember the general rule was 1,000 to
1,500 hours before a rebuild.

That must have been a "rule" made when engines were still "detroit
iron". Once the Japs showed us you can make a better engine, all of
them will run many thousands of hours.
My Yamamerc 60 had over 3000 on it with no indication it was in need
of anything. I got rid of it because of all of the other $200-500
screw on parts that were nearing end of life.

I wasn't referring to outboards. Was talking about I/Os that use car or
truck engines like the popular GM 350, 454, Ford 460, etc.

OK but these days an engine will easily go 5000 hours or more in a
car. There are plenty of 200,000 mile Hondas, Toyotas and even Ford
trucks around and most got pretty shoddy maintenance in the last half
of their lives.
Cars usually get junked because things other than the engine go bad.
Hell my 71 Jeep 304 had 170k miles on it when I sold it (running) and
same with my 69 Corvette. Those were old technology detroit iron
running 70 miles a day on the beltway plus my "around town". Both had
the **** kicked out of them.
Neither were in salt water tho. I suspect it is corrosion that kills
I/Os, at least that has been what I saw.

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.