Flywheel housing, does it matter

[MapisM]

I'm looking at the specs of a couple of early 90s engines, the MAN D2842 LE401 and the MTU 183 TE 92.
Pretty similar stuff (both 22 liters V12 and 1000hp @2300rpm, in pleasure rating), but allegedly the flywheel housing of the former is smaller than the latter (SAE 1 vs. SAE 0).
Now, aside from not understanding the reason - particularly considering that AFAIK both engines are built around the same Mercedes block, I was wondering if/how/why such difference can be relevant...
Thanks in advance for any suggestions!

 

[Bouba]

I'm looking at the specs of a couple of early 90s engines, the MAN D2842 LE401 and the MTU 183 TE 92.
Pretty similar stuff (both 22 liters V12 and 1000hp @2300rpm, in pleasure rating), but allegedly the flywheel housing of the former is smaller than the latter (SAE 1 vs. SAE 0).
Now, aside from not understanding the reason - particularly considering that AFAIK both engines are built around the same Mercedes block, I was wondering if/how/why such difference can be relevant...
Thanks in advance for any suggestions!

Well without knowing any of the facts this is my opinion; the fly wheel is a changeable item, smaller will give a more revy engine quicker more responsive. So I would check flywheel size and weight

 

[MapisM]

I understand the principle, but what made me curious is the difference between two similar engines with the same displacement/power/rpm (not sure about torque, but the difference is bound to be very small - if any), and meant for the same usage (light duty rating).
Btw, as I understand, the ZF 650 (aka BW 165) gearbox to which the MTU was frequently mated was available with both SAE 1 and SAE 0 bell housing.
So, also the gearbox coupling doesn't seem to explain the difference...

 

[Latestarter1]

I understand the principle, but what made me curious is the difference between two similar engines with the same displacement/power/rpm (not sure about torque, but the difference is bound to be very small - if any), and meant for the same usage (light duty rating).
Btw, as I understand, the ZF 650 (aka BW 165) gearbox to which the MTU was frequently mated was available with both SAE 1 and SAE 0 bell housing.
So, also the gearbox coupling doesn't seem to explain the difference...

You generally go up in FW size in commercial applications, if you are spinning a big wheel in heavy displacement vessel, going from ahead to astern at idle rpm engine possibility of stalling. SAE 0 is a real big heavy flywheel/housing with loads of inertia, I only ever spec it on Cummins QSK 38 in trawlers and the like.

 

[MapisM]

I only ever spec it on Cummins QSK 38 in trawlers and the like.

Now, that's interesting.
Do you mean that any given block can be mated to different flywheel housings? I wasn't aware of that.
Could explain the reason why I came across a specs sheet mentioning SAE 0 for that MTU engine.
In fact, the version I mentioned (183 TE 92) is the light duty one (1DS, in MTU jargon - 735kW @ 2300rpm), but there is also a continuous unrestricted one (1A - 550kW @ 2000rpm), used in workboats.

 

[Portofino]

Are you looking in the wrong direction ?
Stern gear - t,other side of the FW .
Depending on g box ratios and weight of boat ,shaft , prop pitch etc , one application may need a bigger FW .
We're the two installs in exactly the same hull? With identical sterngear?

With 20 years ago tech ?
Or if so diff internal mass of spinning moving parts - eg ( not extensive ) but alloy pistons vs steel pistons ,lighter one requires a bigger FW in that particular application ?

 

[No Regrets]

Is one gearbox a reverse type to counter rotate the props? this might result in a higher internal gearbox mass and thus smaller flywheel?

 

[MapisM]

Are you looking in the wrong direction ?
Stern gear - t,other side of the FW.

Pardon...

Anyway, if (as I understand from LS1 reply) the fw housing is replaceable depending on application, that alone explains my doubt, I reckon.

PS: ref your other questions (and also the one from No Regrets), nope, the two engines I mentioned in my OP were pretty much aimed at the same application (light duty pleasure boats), and rated consistently.
Besides, the g/boxes they were usually coupled with were not handed, afaik.

 

[Portofino]

Pardon...

Lets stand on the output shaft and take a little walk .
Two directions we can go --- into the engine or into the g box , hence "direction " inference in post #6 .
Both blocks are made I understand ( happy to be corrected ) by a reputed German casting firm ,who supplies anybody .
That's why MAN and MTU ,Ithink one or two others -? --seemingly share the same blocks and occupie the same power nodes at key positions in the market ( both boats and trucks ) --a boat builders dream ,there's allways another supplier waiting .
Each supplier then fits them out --doing what they want ,here differences start to creep in .
Let's look at the engine side 1st
The rotating internal components may have different a mass and other moving parts --so much so that lighter version -may necessitate a bigger FW along with a bigger bell housing ., to meet the kinetic energy requirements of the G-box /stern gear ,to prevent stalling .

Let's look the other way some G-boxes might be heavier than others , connected to a grater mass stern gear ,heavier shaft , prop and bigger pitch , heaveir boat = just more inertia to get moving etc ,----here too a bigger FW might be needed to prevent stall along with the bell housing .

You did not specify the exact application ,ie which boats ,just vague ish "same application "
There will be a sum of small differences in the factors above necessitating one needing more stored kinetic energy in the FW than the other ,even in a leisure boat -light duty set up .

Another factor ATBE ,in the one with the lightest FW ,they may want to reduce the time to plane time ,ie inc acceleration
Lighter FW,d engines spin up faster .
On my boat from 1200 to say 1800 ,it pushes you back in your seat , glasses and plates slide back on tables ( not due to tilting ) and standing folks have to hang .... If I gun it so to speak

Fwiw -in NoRegrets example -if the G box has more internal mass it actually will need a bigger /heavier FW -to prevent stalling when the clutch plates suddenly come together .

It will not be an accident the diff in bell housing and FW size ,it will be calculated .

Interesting to see if any actual difference of the internal components by the various customers of the blocks ?
The lighter route as well as more responsive ,(hardly a + ve attribute in a marine diesel ),---but crutially may have a slightly greater top end RPM ,say 2300 WOT as opposed to 2150 -- this may have knock on effect with the power delivery curves , like for like -same leisure application ,which may influence the prop curve /choise ,which may influence ,depending on how good the designer is the overall performance of the boat .

The FW mass difference is there for a reason .

 

[MapisM]

You did not specify the exact application ,ie which boats ,just vague ish "same application"

Well, I didn't specify that because I don't think it matters.
Those two engines were installed in all sort of pleasure boats - AZ, Fairline, Ferretti, sportfisherman of several brands, Magnum, Itama... You name it.
And while I agree that in theory the requirements of a Magnum are different from a more sedate f/b boat, I don't think that really matters in practice, when builders decide upon one or the other brand.
With engines, I believe that all the builders are interested in is power, weight, dimensions and of course the price at which they can get them.
In fact, even when you look at similar boats, like the 90s Magnum 53 and Itama 54, I'm very skeptic that the flywheel had anything to see with the reason why one was (mostly) fitted with MAN and the other with MTU...
Assuming that the flywheel were indeed different, that is. According to what LS1 said, probably they were not, in those installations.

Understood ref "direction".
For a moment I though you were suggesting that there are engines with the flywheel attached on the other side... Phew!

 

[Portofino]

Me too -agree ,the one with the heavier FW fitted was because it needed more kinetic energy adding to the exsisting KE generated from its own moving components -- with that particular transmission /stern gear ,in that particular application .

Going fwds if you are looking at 90,s "ladies "powered by MAN or MTU - I would dig deeper into the internals ,try and find out what differences if any ( I,am sure there will be some ) -that may shake out in maintainance issues -
Eg , if the internals are light and it revs up ,has a higher WOT rpm ( to squeeze every last horse out ) ,then it may have a more elaborate crank damper ?

FW size of the FW as you infer is pretty irrelivent and a none issue in my book ,as Long as you know why?
Buy may give an indication of stuff like a heavier G-box /stern gear --etc .

As a new owner if you sell it 5 y down the line ,any long term design Issues are not going to show up or be relevant to your
MAN powered Boat or MTU
20-25 years on ,several owners later ---then traits will have developed .
Itama used both ,more so MTU in the 90 ,s then at of the turn of the century biased towards MAN .
Now back to both ,the MTU 1825 ,s in the 75 ,
MAN 1360/1400 in the 62
MAN 450 ,s in the 45
Just one option for each ---or coursed these are different animals to 90 ,s tech
Point is the blocks come out of the same factory

 

[Latestarter1]

Not 100% certain but MAN 28 Series and MTU 2000 Series from comments made in discussion with MTU inferred that common block sourcing ended many years ago. MAN still use old 128mm bore dimension growing stroke from 142mm to latest 157mm now folks are less phased by piston speed than they used to be. MTU 2000 is 135x156 all indicates that engines now at best distant cousins.

SAE 0 and 1 FWH's appear to be options on both MAN and MTU however I do see that certain transmission/engine configurations demand a specific FWH which would indicate spec is much to do with torsional compatibility.

Forget about differences in spooling up speeds due to difference in flywheel weight, that stuff is for gasoline girls, you will never detect any difference. On a lightly built vessel heavier FWH will make for smoother installation however larger FWH will demand wider engine beds which can often be difficult to achieve, all down to horses for courses and often a good dose of experience at the design stage.

Out of interest I was not aware that MAN had 12.8 leisure rating as low as 450hp, lot of cubes for this output..

 

[MapisM]

Forget about differences in spooling up speeds due to difference in flywheel weight, that stuff is for gasoline girls, you will never detect any difference.

LOL, I suspected that. Good to get you confirmation, though! :encouragement:

 

[Portofino]

Out of interest I was not aware that MAN had 12.8 leisure rating as low as 450hp, lot of cubes for this output..

Since Feretti took over After a few years figuring out what to do with the brand ,in 2005 they streamlined the hulls to 3 ,re naming them ,the chosen 3 .-to 45,62,75
They also --let's just say "changed " the Bulid process of the hulls and likely other stuff -they are a lot lighter now .
The 450 Hp is from the 8.3 L MAN ( eight . Something -think 3?) block -for the 13-14M hull variant that they called the 40 . Displacing 12000kg .only !
This morphed into 45 a few years ago and is now powered by aCuminins 480 .Still 13-14 M but beam 3.95 M

The pre Ferreti 13-14 m segment had
The 42 ( which I have ) MAN 700,s 12.8 L straight 6,s with 4.2M beam -17000kg remanded 48 in 2003 -exactly same spec
46 --MAN v8 800,s I think 14.something L - 4.46M Beam -same 13-14 M L but 23000 kg -from 97 -2001 /2002 ish ?

In the 90 ,s era where MapisM has been looking I think I read somewhere of the foundry that supplies MAN and MTU .
But as you say that's a long time ago and now they -or one of them probably fallen out and sorce somewhare else .
It's just that all the L -displacements- are the same for that era .

Interestingly I,ve just looked at where mine is now the 12 L straight 6 block originating from the D28 series .
It's gone from 12.2 - 12.8 to 12.4 same 128 bore .-I think up to 900 hp eek
Started 490-510 with I think the 12.2 then - 700 -730 --800 - 12.8 L-now I think 900 hp 12.4 L

Any how the smaller 13-14 M hull they call - 45 now has 8 . Something Cummings block 480 hp .
They have ditched the 12.? L block ,along with a lot of Kg,s

 

[Latestarter1]

The 450 Hp is from the 8.3 L MAN ( eight . Something -think 3?) block -for the 13-14M hull variant that they called the 40 . Displacing 12000kg .only !
This morphed into 45 a few years ago and is now powered by aCuminins 480 .Still 13-14 M but beam 3.95 M

Any how the smaller 13-14 M hull they call - 45 now has 8 . Something Cummings block 480 hp .
They have ditched the 12.? L block ,along with a lot of Kg,s[/QUOTE]

MAN 0836 108x125 6.87 liter, worked well at 450hp then MAN took it to 550hp and it ended in tears, only case I am aware of where manufacturer having to withdraw engine less than a year following launch but not before some poor suckers purchased a few in Hardy boats. Seems like some brainless engineers at MAN forgot that 0836 had its roots in a 5.5 liter engine.

By the way no 'g' in Cummins.