Interesting Volvo Technical Data

[Bluefin 32]

Some of you may have seen this information previously but I thought I would pass on a discovery. The website of the French Volvo Penta unit has much more detailed specification sheets that have all sorts of interesting technical data. I thought our engineers on the board might be able to make somethimg of it.

The link is: http://sra-moteur.com/volvo/fr/pages...47&moteurType=

The page is in French but just select the motor of interest and then click on "documentation technique specifique" and you will get the data sheet, which is in English.

From the data on these sheets, it seems that the D4-260, D4-300, and D6-330 are virtually identical in fuel efficiency per horsepower produced (within a percent). The D6-330 is R4 rated for 800 hours light commercial duty with 5000 hours to overhaul, while the two D4 engines are R5 rated for pleasure duty up to 300 hours per year and 2000-3000 to overhaul. The D6-330 puts out less smoke at WOT but they are all about the same at normal 2500-3000 cruise rpms. The D6 has lower maximum EGT and turbo boost pressure as would be expected from the significantly lower horsepower/displacement ratio.

Now if we had this data for the Yanmar 6LP we could trigger another big debate.

[backman]

Neat

where did you see the hours to rebuild? I found the rating, but not the hr's to rebuild.

Says the guy at 1200 hr's on a 2-3K to rebuild engine !

[Bluefin 32]

That is elsewhere on the site in the definitions of the ratings (in French). You have the 260 which running at lower temperatures and pressures than the D4-300 so I would imagine you would be at the upper end of the longevity range, especially since many of your hours I would guess are at 70-75% load based on the fuel burn you say you average on long runs offshore.

Won't you have a 32 or 35 by the time you get to 3000 hours?

[backman]

Load factor

surprisingly when you do the math on a canyon day trip which is the highest engine load trip I can model - 14 hrs clock time/ 7 hr's steam at 20 GPH/7 hr's troll at 3 GPH you come up with 80 gallons per side.

That equates to averaging 6 GPH over 14 hr's which is less than 50% load. Shorter day trips - Dump or Lanes or the Sword are even less and equate to 40% load.

And yes; I will move up in 2-3 years once I get past a few more college semesters

[Bluefin 32]

Load

I don't think you can view the load in the average over time as you calculated to establish the impact on the motors. In your example, it is more like 7 hours at 70% load (or whatever 20/WOT fuel burn is actually) and 7 hours at 10% load. Running 4 hours at 100% load and 4 hours at 10% load is most definitely not going to produce the same engine life as 10 hours at 55% to give an extreme example.

[Oswego]

D4 vs D6 in a 28

I wonder about the economics of having a D4 vs. D6.

I was quoted a price of approximately $8,000.00 extra to go from a D4 260 to a D6 330 (per engine). Everything else being equal (which we know it never is) then theoretically you get an additional 2,000 hours for the $8,000.00 (or $16,000.00 for both engines).

Does anyone know the cost of a rebuild for a D4 260 or 300?

I'm just guessing, but if it is $15,000.00 per engine, then the D4 would cost an additional $7,000.00 ($15,000.00 - 8,000.00 = $7,000.00) to achieve the same 5,000 hours. Of course, you would still have the additional 1,000 hours left on your 3,000 hour rebuild with the D4 and would be rebuilding the D6 and facing whatever the rebuild cost would be.

I guess the advantage to the D4 is the $8,000.00 savings upfront.

This, of course, assumes we plan on keeping our boats for this long before moving up to a 32 / 35 ...


Tom

[Bluefin 32]

Lifespans

Other than a commercial very high hour user (or maybe Backman) who puts on 600+ hours per year, it is hard to imagine coming out ahead on the differential just because of the time value of not putting out the money up front. The big unknown is whether a D6 boat has an advantage in the resale market that allows you to recapture some of the upfront premium. That might be the case since there will be fewer of them.

It is more an issue of whether you want to pay for the small performance differences and the possibility that the D6 might be a little more reliable in service being less "high strung". There are some other differences that can sway the decision too. For example, I wanted to avoid an engine with a compressor (supercharger). I believe the D4-300 has one but the D6-330 does not.

In any case the time to rebuild estimates are very soft and affected by innumerable factors. I offer the example I have mentioned before of a charter captain friend who has a Yanmar 6LP with 6,000 hours with no rebuild that has excellent compression and runs perfectly-- far more hours than it is supposed to run before a rebuild. Of course there are also many examples of motors that have needed rebuild in far fewer hours than the expected time.

I gave up many years ago pretending that anything relating to owning a boat was rational. Even a friend who is one of the last remaining full-time commercial fisherman up here refers to it as his "hobby" due to the catch quotas and shrinking numbers of bluefin and close-in swordfish.

[backman]

Lifespan's - alternate view

An ACK friend and I have both reached the conclusion that the right thing to do WRT high output diesels and recreational fishing in the NE is to treat the engines as disposable as opposed to rebuildable; run the engine right through the extended warranty; then replace before a major bill$$ occurs.

the rationale is thus - even "heavy" user's like myself have to work really hard to put more than 500 hr's/year on the engines. W/ a typical 5-6 year warranty your at 2-3K hr's right when the warranty runs out; right when components like pumps; exchangers, turbo's; etc. start to show age. W/ as has been pointed out a rebuild being roughly 1/2 the cost of a new engine, and in our case, a rebuild requiring a lift out, then reinstall - why not lift out; sell the old engine as a runner and upgrade to newer and more modern engines.

As an example - when my old 42's were 7 years old I had the choice of spending ~10K per side to rebuild or buying new ones for double that. When i found the old ones had value; the equation changed even more.

Effectively I was looking at a fixed cost to remove and reinstall engines+ whatever engine room, running gear and wiring cleanup was needed regardless of rebuild or new.