MAN 10V-1100 (D2840 LE 423)

I never liked any version of V10 MAN engines, because they are rougher than both the V12 (which is unquestionably the smoother of their modular engines) and also the smaller V8.
It's no coincidence that after sticking to it the Common Rail in the LE423 version, MAN phased out the V10 altogether, and focused their developments on the V8 and V12 blocks.
That said, my understanding is that the LE423 was at least better than the semi-electronic, non-common rail LE403 (1050hp), which was a not so reliable version developed upon their last mechanical V10 (the 820hp LE401, which had instead a decent reputation).

Sorry, I can't suggest any good MAN dealer in your area of interest, but I would certainly involve one for the survey & seatrial.
On top of all the usual reasons, he should be able to find for you (unless the previous owner already has it in the boat papers) a copy of the original test performed upon commissioning for validating the warranty.
And a comparison between the numbers recorded back then and all the present ones reported by the MMDS displays can give you a very valuable picture.

Good luck!

I'm not sure of how your feeling is opposite of mine, overall.
You agree with me that the LE403/1050 was a POS - why am I not surprised to hear from the OP that the previous owner binned them?
You agree with me that the LE423/1100hp was better - as well as the LE401/820, which in fact did not have any cylinder partialization, being 100% mechanical.

You seem to prefer the V10/1100 to the V8/1200, and that's where our views are different.
Now, when it comes to personal preferences, who am I to argue?
BUT you shouldn't trust gut feeling, as I guess you did, for evaluating an engine.
Its performance can come across anywhere between poor and excellent, depending on the installation.
In fact, also if we want to leave aside the not irrelevant fact that the manufacturer phased out the V10 block completely after the LE423, and invested heavily on completely new V8 and V12 basements, your impression on torque is completely wrong.
The V8/1200 torque is about 200 Ft Lbs higher than the V10/1100, and steady over a wider range, starting from 1200 rather than 1400+ rpm.

That said, it's perfectly plausible that a boat runs well with the V10/1100, and another runs poorly with the V8/1200.
It could even happen for the same model of boat, btw.
Weight distribution is bound to be a bit different for instance, when using blocks of different length.
But the only conclusion that can be drawn is that the former overall installation is better than the latter, not that the engine as such is.

Fair enough, but again, there can be plenty of technical reasons behind the behaviour you are describing, torque being just one of them.

In fact, for all the faults of the LE403/1050, its torque was hugely higher (>500 Ft Lbs!) and much more steady than in the LE401/820 - as is logic to expect with electronic vs. mechanical governor.
Btw, I don't actually remember all these engine specs by heart, just in case you are wondering.
I just happen to have a good database of specs sheets and manuals in my notebook, so it only takes me half a minute to check them.

Anyway, the only sound conclusion you can draw from the fact that the V10/820 powered boat which you tried was less load-sensitive than those with the V8/1200 and also the one with the Cat is that overall it was a better designed installation, certainly not that its engines as such were better.

If you are happy with the powerplant in your Viking, good for you.
And if that Scott Marine Power chap thinks that the V10/1100 is one of the best engines ever, well, that's a respectable opinion.
I could mention three among the larger Italian MAN dealers, two of which work closely with builders for OEM installations, whose opinion is exactly the opposite on the V10 block in general, though with some differences between the different versions, as previously discussed.
But when talking of opinions, we can debate till the cows come home and reach no conclusion.

At the end of the day there's only one thing we are sure of, because it's by now history:
After MAN jumped on the common rail bandwagon around the mid naughties, they were able to squeeze more power from all of their engines.
Courtesy also of 4 valve heads actually - it wasn't just electronic gizmos that made them good for up to 900, 1100 and 1360 hp - respectively for the V8, V10 and V12.
BUT, they soon realized that there was room for further power growth, if it weren't that the crankcase was working at its structural limits.
So, they decided to bite the bullet and redesign it completely (though still around the archaic 128mm bore M-B blocks), to make it more robust and capable to withstand a longer stroke crankshaft.
And guess what? In that occasion, they decided that only the V8 and V12 were worth such investment, and phased out the V10 block completely, stopping its production already 10 years ago or so.
These days, not only the V8 and V12 based on these heavily redesigned blocks are available up to 1300 and 2000 hp respectively, but there are also the equivalent, de-tuned medium and heavy duty versions.
For the records, also back in its days, a heavy duty rating V10 never existed, it was only available in light and medium duty.

Bottom line, maybe the German engineers at MAN knew something that the Scott Marine Power owner didn't.
Or maybe the opposite, who knows?

Neither MAN nor other major manufacturers design their blocks specifically for marine applications.
They just marinize something designed primarily for other larger markets.
In fact, they phased out the V10 also from their construction machinery, locomotives, agricultural, power generation, you name it.

The choice of bore/stroke ratio upon redesign was just a matter of costs.
Essentially, to increase the stroke to 157mm and produce more power, they "only" had to redesign and strengthen the lower half of the crankcase, together with a new crankshaft, obviously.
Higher bore would have meant a totally new block.

Ref. what folks say on your side of the Pond, if you tell me that the V10 was highly appreciated I take your word for it, and I'm not disputing it at all.
But we are back to opinions.
Mine, aside from chats with MAN engineers, is based on 3 boats I tried, powered by the latest V10s: 820, 1050 and 1100 - and none of them impressed me (the 820 being actually not too bad, the 1100 a close second, and the 1050 way behind both).
But that's yet again just an opinion, and I'm certainly not pretending that 3 boats is a solid statistic base, anyway.

OTOH, what MAN decided to do (or NOT to do, in the case of the V10), as opposed to opinions, is instead history by now.

Mapism I sincerely enjoy your posts and find them informative. So not at all trying to start something. But, I am pretty sure you are wrong about the 820 V10 not having cylinder cut outs. I believe this was debated in a previous thread. I realize this is an opinion but it is relevant one based on 10+ years of ownership. The 820s vibration is exist but not an issue. The 820s have an excellent deserved reputation for longevity provided you take care of them. I have 200o hours and still have crosshatching on my cylinder walls. They may let me down tomorrow but till this point they have carried me to the Bahamas and up and down the east coast numerous times and have been rock solid. Like Capt J says they run the same speed full of fuel, water, and dinghy on the bow and don’t pick up speed as the fuel is used up.

Yup, we did discuss the partialization in the past, and it appeared that what I was told about the lack of it in mechanical engines was wrong.

I can't actually be positive on that, but yes, AFAIK Baudouin is only focused on marine applications.
Another manufacturer I can think of, whose engines are specifically designed for powering boats (albeit at the opposite end of the scale, i.e. high performance/fast patrol/racing) is Seatek.

When I said "major" manufacturers, I was more thinking to the usual suspects that you can find on mainstream pleasure boats, where you are extremely unlikely to find either Baudouin or Seatek.

Ref. your last question, the answer is bound to be yes, in principle it could be an advantage if an engine is designed from the ground up for marine environment. But at the end of the day, what really matters is the marinization part, and that is obviously engineered specifically also for all other engines derived from industrial versions.