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Old 10-16-2013, 01:37 PM   #141
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You have not managed to convince me that I am wrong, but you are also too hidebound to accept my opinion.
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Some of us have expressed in the past our relative experiences, not a lot of detail mind you, but a hint as to our creds. Just curious, what are your diesel experiences?

BTW, I was working in Canada when the French Canucks went nuts and tanks were rolling in the streets. I much prefer loudmouth know nothing's to the business end of a cannon.
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Old 10-16-2013, 02:55 PM   #142
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I didn't suggest that the 600 hour engines were underloaded, I merely asked for some evidence. Reading comprehension seems to be a weak link on this site.

Enjoy your boating.
Well then what are you suggesting? I suggested some causes. I am heavily vested in the iron that is down in my bilge...like most of us are. Which means I do a lot of reading. I have learned a lot since that iron could cost me a lot of money to replace. Those 3 things in my post are some of the more likely causes of premature failure in Cummins engines....and likely the engines you listed. Diesel engines don't fail early for no reason. And marketing drives the engine types for recreational boating....IOW...highly powered "light" engines for boats that plane....which is kinda where this thread has crept... Maybe my fault. But engines put in boats that are not meant to plane are even less likely to fail prematurely.
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Old 10-18-2013, 08:07 PM   #143
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Interesting about Cummins. I'm in the process of buying a 250 hp 6CTA83-MI. Just one.
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Old 10-18-2013, 09:00 PM   #144
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The Gwaii Haanas is an interesting looking boat.
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Old 10-18-2013, 09:03 PM   #145
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Don't own it yet, haven't done surveys or trials yet so I don't want to jinx the deal. But yes, it is cool, I'll never see another one, which is why it's difficult to buy.
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Old 10-18-2013, 09:24 PM   #146
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Interesting about Cummins. I'm in the process of buying a 250 hp 6CTA83-MI. Just one.
That is interesting that you posted that because I was going to mention something about engine "ratings". I am not familiar with the 250hp version of the 6CTA. That means that engine is very significantly derated. The highest power version of that engine is 450hp...if I am not mistaken. Think of it this way....you are running the 450hp version of that engine at a little over 50% power...and that is assuming you are running it 100%(250hp). That engine will last forever at that rating!!!! And even the 450hp versions are pretty stout engines and are not boosted as heavily(per liter) as my 6BTA.
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Old 10-20-2013, 06:54 AM   #147
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To me the best way to select an engine for >forever< operation is to go to the MFG site and look at the lowest power rating for that engine and find its 24/7 rating.

If that (HP/RPM or less) is where you will be cruising ,,amusing yourself purchasing a rating 50% or even 200% higher does no harm.

AS long as there will be some positive boost at cruise a pair of turbos , and intercooling will do no harm.

And you might get a blast once in a while defueling at 1/2 NM/ per gallon , and tossing a fish killer sized wake.
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Old 10-20-2013, 11:09 AM   #148
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To me the best way to select an engine for >forever< operation is to go to the MFG site and look at the lowest power rating for that engine and find its 24/7 rating.

If that (HP/RPM or less) is where you will be cruising ,,amusing yourself purchasing a rating 50% or even 200% higher does no harm.

AS long as there will be some positive boost at cruise a pair of turbos , and intercooling will do no harm.

And you might get a blast once in a while defueling at 1/2 NM/ per gallon , and tossing a fish killer sized wake.
Or you can derate it "yourself". Just don't operate the engine at the higher power settings.
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Old 10-20-2013, 12:17 PM   #149
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"Or you can derate it "yourself" ".

Hmmmm For one I don't know more about rating an engine than the engine manufacturer. I'm inclined to follow the recommendations set forth by the manufacturer.
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Old 10-20-2013, 01:42 PM   #150
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"Or you can derate it "yourself" ".

Hmmmm For one I don't know more about rating an engine than the engine manufacturer. I'm inclined to follow the recommendations set forth by the manufacturer.
I think you missed the point, eric... Engines are rated by the manufacturer for a specific purpose. Recreational Marine diesels are usually in the higher ratings because that is what the market demands. But in the case above...you have basically the same engine....one is rated at 450hp...the other at 250hp. You could just operate the 450hp engine(ie say 150hp) in the same manner you operate the 250hp and you have basically derated the engine yourself!!!! simply by the way you operate it. Engine manufacturers derate engines for longer life and longer maintenance intervals. That is why you hear about generators that run 100% 24/7. The engines that run those generators are likely very capable of producing significantly more power than their 100% rating. But the manufacturer derates them so they can be run at "100%". If you think they are running balls out on the ragged edge like it sounds, you would be mistaken.

To put it more theoretically, the (de)rating is somewhat arbitrary.

Go easy on me Rick!!!!
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Old 10-20-2013, 02:04 PM   #151
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Or you can derate it "yourself". Just don't operate the engine at the higher power settings.
On a planing boat that makes some sense to me. If the 450hp version is properly propped for full throttle M3 rating it will have more pitch than an 250hp version of that engine. If operated at displacement speed one should get better mileage than the lower rated engine because the lower rated engine would have a finer pitched prop. I wouldn't be comfortable doing that without an EGT gauge. If I were to do that I would look at the max: rpm / manifold pressure / egt that the manufacturer recommends for that engine used as a continuous duty gen set and as long as none of those parameters were exceeded I would expect a long and trouble free life. I would not operate a highly loaded turbocharged engine without an EGT gauge.


As an aside:
I've seen pictures of a tractor operating in a test cell and the whole exhaust system to the turbo was glowing a dull red. EGT was at a normal range for field work. When I added a turbo to my tractor my friend from the test cell said that if I didn't exceed 850c measured within 6in after the turbo I probably wouldn't have expensive noises. I only have a few hundred hours on it at heavy load but so far so good.

I was slower at typing than Baker. What he says makes sense to me.
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Old 10-20-2013, 02:23 PM   #152
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I think you missed the point, eric... If you think they are running balls out on the ragged edge like it sounds, you would be mistaken.
You pretty much nailed it, Baker ... you've been holding up the enlightened side quite well.

Depending on the engine there might be subtle differences in injection timing, valve overlap, boost, and with CR engines some of the computer programming that controls injection rate and timing but the hardware is pretty much the same.

As far as the claims, fears, and warnings about temperature a few posts back ... think for a moment about the good old Gardner diesel that powers Benn's boat and one of the ones I play with regularly, those same engines will probably be running just as well in 2113. The factory spec coolant temperature for those engines is between 140F and 165F. Oil temperature is supposed to be between 124 and 140F. Gardner suggests running the engine at "fast idle for some minutes" (whatever that means) before applying full load.

If everyone who operates a diesel for a living worried half as much about the things as a handful of hobbyists seem to we would probably still be shoveling coal into little fire tube boilers on our steamboats. Or, horror of horrors ... burning deadly dangerous petroleum spirits in diesel look-a-likes.
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Old 10-20-2013, 02:45 PM   #153
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If everyone who operates a diesel for a living worried half as much about the things as a handful of hobbyists seem to we would probably still be shoveling coal into little fire tube boilers on our steamboats. Or, horror of horrors ... burning deadly dangerous petroleum spirits in diesel look-a-likes.
Another gem...
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Old 10-20-2013, 02:50 PM   #154
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Good point.
I nearly bought a Gardner-powered trawler. The owner warmed it up at 400 rpm, which was interesting, but what put me off was the polishing - the aluminum castings, the brass nuts and the copper and brass plumbing was all polished! It was (expletive deleted) gorgeous and I had peculiar, slightly perverse dreams about it for weeks, but finally the wood hull and the concrete ballast added to the multi-gallon Brasso-tank finished me off.
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Old 10-20-2013, 03:39 PM   #155
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... the wood hull and the concrete ballast added to the multi-gallon Brasso-tank finished me off.
Salt and vinegar will take care of the concrete and wood. Just have the Brasso tanker pull up at the fuel dock and your world will shine.
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