Man 2848LE 800HP V8

Yep, I kinda knew this but forgot from other engines, including SBCs and Outboards.
When we built up SBCs using the 400ci rigs, red line came down.
Built up 3 liter Mercs over the common 2.5Ls, red line came down.
Longer the stroke, red line has to come down,, or else..

I'm not MAN heavy and did not realized your rig had an increased stroke. The joy of these forums, we always learn something new all the time.

Thx

But, that MAN 6 lung (IMO) could certainly still take it if needed.

That's not correct, F42. The stroke has always been 142 mm, for V engines.
It's true that the D2866 had a 155mm stroke, which in your D2876 was increased to 166mm.
But in both cases the red line was at 2200.
On the other hand, in the common rail 730/800, the stroke remained 166mm as in the D2876, but they increased the rated rpm to the same 2300 of all V engines.

Therefore, obviously different stroke alone can't be the reason for the different max rpm.
But don't ask me which were the other evaluations of the chaps in Nuremberg, if any.
To my simple mind, both keeping the same 2200 rpm when the stroke was increased from 155 to 166mm, and also increasing it to 2300 later, had more to see with the marketing thirst for power, which is what sells engines, more than anything else.
After all, they are also part of VW Group now, if you see what I mean...

Just as a last note, in the late noughties MAN realized that they couldn't keep squeezing more power from V blocks originally designed for a much lower output, so they decided to bite the bullet and redesign the crankcase and crankshaft completely.
In this process, the stroke of V engines was increased to the current 157mm, with a correspondingly higher displacement.
So, they are now offering up to 1300 and 2000 hp (always @2300 rpm), respectively on the V8 and the V12.
Which is quite a jump, from 900 and 1360 of the last 142mm stroke V8 and V12.
This did not involve the inline 6 though, whose last power increase was in fact rather limited (800 to 850).
And neither it applies to all the previous generations V engines which we discussed so far.
The only exception is the V8/1200 mentioned by CJ, which is indeed one of the latest 157mm stroke V engines.

So, To the OP Cabo47. Seems to be some serious MAN kids here.
I know I have learned a lot. With support like this on YF at no extra charge, WOW..
Seems the hours on MTBR seems good to better if well maintained.
Lets go water skiing soon..
,rc

LOL, it's rather that Greek MAN dealer whose website shows those numbers which is a bit crazy, methinks...
They must have made a cut and paste mistake or something, because neither the 199 l/h for 730hp nor the 213 for 800hp pass a basic sanity check.
For your reference, I am attaching the official MAN leaflet, where at page 4 you can see that the right numbers are 145 and 158 l/h respectively, not 199 and 213.

You might find interesting an old trick which I learned many years ago from an old school mechanic, who forgot more about marine diesels than I'll ever learn in another hundred years.
Whenever you want to know how much fuel a diesel engine burns, don't even bother looking at specs.
Just take its rated output in hp, divide it by 5, and you'll get a very decent estimation of its fuel burn in liters per hour at WOT - it's that easy.
And you know what? In the last two decades, I read about all sort of bells, whistles, and claims of improvements in fuel efficiency: from mechanical engines to electronic governors, HEUI and MEUI injectors, common rail - you name it.
But at the end of the day, all these claims always happen to be very close to the "5 hp per each liter/hour" good old rule of thumb.
Which frankly, never fails to make me smile.

Back to the engines discussed so far, let's see what this rough estimate gives us, and cross-check that with the official specs:

V8 800: 800/5 = 160 l/h rough estimate vs. 162 l/h of MAN specs (i.e., a difference of +1.2%);
V10 820: 164 vs. 160 (-2.4%)
V8 1200: 240 vs. 240 (right on the money);
6 700: 140 vs. 136 (-2.8%);
6 730: 146 vs. 145 (-0.7%);
6 800: 160 vs. 158 (-1.2%).

If there is a ballpark rule of thumb which can give more accurate results than this one, I'd be curious to hear about it.

That said, two important considerations on the above numbers:
1) according to MAN, tolerances up to +5% (i.e. well above the previous differences!) can exist also within different units of the same engine model;
2) what these numbers tell us is that all the fuel efficiency claims, from archaic mechanical engines all the way up to the latest and greatest electronic CR like the V8/1200 and the R6/800, are pure marketing BS.

If there is a field where development has achieved meaningful results (emissions aside), it's the power/weight ratio, not power/fuel.
Of course, for any given power, ultimately a lighter boat has less drag and burns less fuel.
An effect which can be somewhat relevant particularly with faster boats.
But this is not an improvement in engine fuel efficiency as such, so to speak.