Man 2848LE 800HP V8

There is not an easy answer here.
All MAN service schedules kept, never overheated, better engine oil and coolant, average loading, wrong propeller loading and amount of fuel consumed means a lot to life long hours on any engine.
You will need perfect records to prove these service points were up.
MAN parts and service is expensive and sadly, some to lots of service items get skipped or cheapened.

That was a great engine, now 900hp and still getting over 4000 hours.

Perfectly serviced mechanical injected 800 Man V8's could see over 6000 hours.
However, because of it's age in years, 4500 to 5000 max, IMO.

Then, some engines were called MAN-grenade for a reason.
I feel this forum (YF) likes MANs and this nic-name was developed from poorly installed or serviced MAN engines.

If you are considering a MAN powered boat, Find a real MAN shop close by.
Go check them out. It will be a shop like this that helps the life of your MAN engines.

Sorry if I was wrong. Questions like his (IMO) usually come from shoppers.
Also Cab047 stated early 2000 engines. Was there piston problems then also?

Beau, You have the V12 version of this engine if I recall correctly? Long life?

I wish I knew the answer to your question, because those engines are exactly the ones running my own boat.
2004 vintage, about 16 hundreds hours clocked, so far so good.
And if they'll last as much as Capt Ralph predicted, they'll outlive me, so I'll take his estimate!

FWIW, I did a bit of homework before buying the boat, and I found a rather widespread consensus about the fact that they were among the more robust engines of their era and in that power node, together with the Cat 3406.
They are in fact the very last of the fully mechanical MANs, with no electronics of any kind.
Essentially the same technology of the V10/820 that Beau has in his boat, but when the V8/800 was released in the second half of the 90s, as an upgrade from the previous 680hp, it overlapped the V10/820 in a lighter package, so they upped the V10 to a semi-electronic 1050hp, and then to the common rail 1100hp, before eventually phasing out the V10 block completely.

A somewhat folkloristic story is the reason why MAN kept building the V8/800 for a few years after they released the common rail V8/900, i.e. up to 2006, as I recall: it was their only engine in that power segment approved for installation in boats built to classification society standards.
In fact, not only the newer V8/900 CRM, but also their inline 6 (available as 700hp semi-electronic and 800hp CRM) did not tick that box.
Now, you can make of that what you will, obviously. It certainly doesn't imply that the other engines were bad.
Anyway, it's kind of reassuring that the older technology was trusted more than the newer one.
But I'm saying this with my fingers firmly crossed!

Should you be interested in more details, just specify.
I know my chicken reasonably well, by now.

Like the bomb proof 3406, The MAN R6s should also prove bomb proof.
One rod bearing per crank bearing keeps that crank shaft straight and powerful.
That's why 6 cly motors can make more reliable HP per lung than V blocks.

You remember the ole Hornet in line 8? Blown it made the most HP per lung in gas engines.

I remembered as a hand in crew, a new MAN (V10s?) boat heading down the StJohns river later 80s from Bronson Lambs yard. Every minute of running, the more block vent smoke came out. When we made back to the dock, both engines died (suspect sized).
They were pulled thru the night and never talked about again. 2 weeks later, that same boat was screaming down the river and never came back.
Bronson never would fill me in on the whole story. Scuttle was new blocks were flown in and fixed all issues in a couple of days.
I had always kept reservations about working on them for a long while. Then SeaRay started selling them.
Fast Forward 20 years, I'm servicing them and crawling all around them. They sling oil as a good Detroit but fixable.
Freaking DanFoss sensors are expensive POS's. Never could cross a Nason sender to them. But, I stayed busy.

You can follow all of my YF threads on MANs I have posted. You need a heavy tech in your area. None (worth a ship) are in this area.
Thru the early days, Performance Diesel in Texas, I guess felt sorry for me; sent manuals and parts and answered all my phone calls.
Great guys. We both kept the customers happy.

Here in the swamp, most of those boats have headed back south and Detroit and old Cummins are the norm.
The big MAN issues these days are refinishing the valve cover caps.
Yep, I'm sure they fixed their issues. You still need bux to deal with scheduled items and these POS senders. Oh, Main logic boards cant remember hours on the later high tech stuff.

I see your point ref. main bearings in principle, but output also depends on manufacturers' choices, to a large extent.

At this size, Cat and also FPT have always been focused on inline engines, but the Germans not so much.
As I recall, MTU never had any inline engines in their lineup, and also among MAN engines, actually their Vs always had a higher specific output, compared to the inline 6.
Obviously, we must take models of the same vintage, in order to make a meaningful comparison.
Back in the V8/800 days, their most powerful inline 6 was the 700 (aka D2876LE401 - the "R6" label came a bit later, with the 730 and 800).
And in spite of the fact that the V8/800 was still mechanical and the I6/700 had an electronic governor, the specific output was higher for the V8 engine, even if just by a hair (54.7 hp/liter vs. 54.6).
In fact, as one of the older MAN dealers told me, they introduced the inline 6 mainly as an alternative for installation in not very beamy boats, where the V8 width could be problematic.
In the following years, they invested even more on V engines, as in you can check in their latest lineup, all fully electronic and CR, where the differences went ballistic.
The specific output reached 80 hp/l for the V8 (and 83 for the V12!), while their more powerful I6 still delivers "only" 68 hp/l.

Not that I'm a fan of high specific output, mind.
Rather the opposite: in a boat, I rate durability well above weight/performance ratio.
Just saying, along the lines of your thoughts...

I have always recommended just an extra few more rpm on the MAN engines.