overloading a diesel engine

[simonfraser]

further to my prop thread

let's say you are overloading your engine(s)
could be a fouled hull, too much junk on board, too many peeps, too much fuel, wrong props, whatever

now you can't reach max revs
this means you are wasting fuel and stressing the engine(s)

what reduction in revs would you run the engine(s) on ?

 

[omega2]

Most books say 200 rpm below max you can pull, as you say if you cannot pull max, then who knows??

 

[scottie]

Most books say 200 rpm below max you can pull, as you say if you cannot pull max, then who knows??

If new then Volvo would not sign off for warranty on these Max revs which is slight Irrelevant now but if not suitable for warranty why do you think it’s ok

 

[Portofino]

As Scottie infers , normally it’s the other way round they should be propped to achieve a tad over the manufacturers rated rpm .2/3 % or something.
If it’s overloaded that’s not just a binary number at the top end , it’s mostly throughout the normal working rev range .So with yours it’s overloaded after say 2400 when the supercharger and then the turbo takes over say 2800-2900 rpm .
So anywhere over this say your man maths 3400 it’s will be overloaded.

I thought you mentioned you retro fitted EGT,s gauges .If so what kinda numbers are they throwing up with theses new over sized props ?
If they are calibrated then that’s where to look for comfort or not as the case may be ?

 

[jfm]

About 70%. I mean 70% of the max rpm you can pull.

If engine rpm are correct at WOT, engine will be under loaded at 70% of that rpm. That's how most are set up. Ergo if you happen to be overloaded at WOT you'll be about correctly loaded at 70%. Very roughly.

 

[simonfraser]

'I mean 70% of the max rpm you can pull'

yes that seems reasonable to me, taking extra stores / fouled hull etc into consideration

but, max revs say 4000, 70 % = 2800 revs
does your mobo plane at 2800 revs ??

 

[BruceK]

Yes on mine. Barely. She will be doing about 16 knots and liable to be knocked off the plane and having the supercharger kick in as below