Cruising RPM for Volvo D2-55

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asteven221

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Does anyone know what the maximum recommended RPM is for this engine when cruising over a long(ish) period of time e.g. 12 hours? Thanks.
 
After posting this I did some Googling and it seems that the the majority of the web sites state "2700rpm to 3000rpm" as the max RPM. Why state a range of 300RPM? I would have thought that it should be a single figure. Seems a little vague to me. I am basically wanting to have the option to cruise at the maximum RPM possible without damaging the engine. Does anyone have any idea what thjat RPM might be?
 
We have this engine and our manual states that cruising revs are around 2200 - 2300. We cruised at these revs all last season and it seemed fuel efficient and quiet, so happy to concur with the technical guidance! Hope this helps.
 
Most marine engines have various fuel injection pumps available to factory and they fit what is best for that particular installation. The rpm rating is particular to each work need.
If you take a pump of a land version of your engine - you are likely to find it higher rpm rated than your marine rated.
I have a spare inj. pump for my Perkins - that is set at 3600rpm max ... a lot higher than the pump already on there. Many pumps will have the max rpm stated on the fixed label either as a separate figure or in the serial number.

For most normally aspirated diesels on boats it's fair to estimate cruise throttle at about 2500rpm+ ... as a diesel is a diesel etc. Slight variations of course.
 
There is not a definitive "best" rpm. The rule of thumb is 75% of maximum revs. Your boat should be propped to give hull speed at around full revs. That makes comfortable cruising at 75% Example my Volvo 2030 gives me 7.3 at full revs, 6.3 at 2700 (75%) I usually cruise around 2500 which is 6 knots.

Revs will not do any significant harm as you are unlikely ever to wear it out mechanically. However that last 25% equals noise and dramatically increased fuel consuption for the extra speed gained.
 
My Bav44 has a D2-55. We motor/motorsail at only 1900-2000rpm even though I know the top rev spec is 3000. Motoring at 1900-2000 she is doing about 6kn in calm/agitated seas. I have only felt the need for more if against wind/tide.
My D2-55 has a saildrive with a Volvo 3 blade folding prop. Boat length/weight/drive/prop will all change the equation of revs to speed of course.
 
You won't damage an engine at maximum revs - in fact diesel engines probably last longer at high revs than at low revs. It's rather a question of noise and fuel consumption.

John.
 
[ QUOTE ]
You won't damage an engine at maximum revs - in fact diesel engines probably last longer at high revs than at low revs. It's rather a question of noise and fuel consumption.

John.

[/ QUOTE ]

But think of the cost in cleaning materials getting all that soot and crap of the hull round the exhaust !! /forums/images/graemlins/laugh.gif

Actually talking to an old hand mechanic other day - I mentioned this - about working a diesel hard. He agreed but added - NOT at constant revs .. and to those who advocate high revs work - engine is metal mechanical as any other - it wears out faster at higher revs and work. Trick is to vary the revs and make engine work all over the range.
 
harstonwood said:
The revs/oil p/temp etc

I think i,ve worked it out I need a y adapter to tap into the instrument feed ( to tye starter/rev counter unit at helm) and an nmea gateway magic box (volvo) partnumber 3889758

Then an seatalk adapter and fingers crossed
Click to expand...

Yes, the 3889758 interface will output EVC data in NMEA2000 format. Mind you, for over £300 it should!
 
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