Engine ratings

Discussion in 'Diesel Engines' started by Mik the stick, Sep 4, 2014.

  1. Mik the stick
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    Mik the stick Senior Member

    It seems to me that all makes of diesel are good reliable engines. Running them with to little load can ruin them so perhaps they are not so reliable as there reputation. I like John Deere engines one reason being they are clearly rated M1 to M4 (see document I posted on previous thread). Beta diesels and Yanmar are also impressive engines. However my documents on the Yanmar range they have a max rating and a continuous rating. No hours per year or hours per 24hr period at maximum rating. If this is marketing strategy then JD does it better.
     
  2. FAST FRED
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    FAST FRED Senior Member

    >Beta diesels and Yanmar are also impressive engines.<

    They are auto marinizations or yard implement tale outs.

    So will have a 24/7 rating that does not please the marketing folks.

    For small engines like the Kubota simply look for the engine when used as a gen set , and use those numbers for the cont. duty rating.

    Yes severe under loading can reduce engine life , 650 hp producing 50 hp is not happy , but for a rec boater . so what?

    Most rec boaters run 200 hours a year , so in 20 years there lucky to see 4000 hours.

    If a fine engine has its service life cut in half , its still more than 4000 hours!
     
  3. Mik the stick
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    Mik the stick Senior Member

    FF, If I am understanding you correctly and Yanmar have a 24/7 rating then they are far better than I imagined. This means a Yanmar 4J4H (99mhp continuous) gives about 6hp less than the John Deere M1 (continuous) rated engine, while saving 539lbs in weight. That certainly makes me a Yanmar fan.:D
     
  4. WestVanHan
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    WestVanHan Not a Senior Member

    ....it means is the JD will last last a few times longer than the Yanmar.

    I think many ratings ( max in a day/year etc) are mostly for the manufacturers to keep warranty costs under control.
    With new electronic diesels and ECUs they can plug into a laptop and tell exactly what you've been up to with the throttle.
     
  5. Mik the stick
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    Mik the stick Senior Member

    So if the Yanmar costs 10 units of currency and the JD costs 14 The JD is the one to go for. I have noticed prices are quoted after an Email request.
     
  6. jmiele3
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    jmiele3 Junior Member

    Sort of

    We manufacture our engines with a rating of medium commercial / government use as standard. For recreational use (100 hours per year or so), the end user tends to have a longer life cycle. The rating is a big cost concern in commercial, however.

    WestVanHan is partially correct about warranty, but getting into it further, a commercial or government user will put the boat through significantly higher loads than the average recreational user. Some of our engines are used up to 3,000 hours in a year. Use that would pretty much destroy an engine rated as recreational. With our ECU, we can control the combustion, and the rating. There is no such thing as a free lunch. More power / torque out of a given block will always have an impact on warranty / life cycle. An example is our VGT Series of engines. All use the same 6.6L block. What is different is the cooling system, ECU programming, turbocharger, and fuel system:

    VGT350 - MTBO 3,000 hours
    VGT400 - MTBO 3,000 hours

    <<different cooling system and turbo>>

    VGT450 - MTBO 3,000 hours
    VGT500 - MTBO 2,500 hours


    There is a reason that warranty documents feature pages of really fine print and loads of exemptions. It is really important when choosing an engine that you actually read the warranty and how certain use is exempt (as in hours per year, commercial / recreational, maintenance documentation, and total hours)

    Some brands (Volvo Penta, Yanmar) tend to focus on recreational users with their ratings (nothing wrong with that). Some offer multiple ratings with virtually every engine (for example, some Cummins engines have 10 or more ratings, as do many CAT engines).

    There is a bit of marketing and PR involved. We are regulated as to the accuracy of the rating (in our case, by the EU, NATO, and ISO standards, not to mention classification), but how that rating is portrayed in sales is a really gray area, as in there are no set standards or regulations...The curves and specifications must be accurate, but that is all.
     
  7. FAST FRED
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    FAST FRED Senior Member

    If I am understanding you correctly and Yanmar have a 24/7 rating then they are far better than I imagined.

    Read again,

    So will have a 24/7 rating ,,,,,,,that does not please the marketing folks.

    The car and yard implement conversions much prefer to hide behind the auto rating and pretend it is thats all there is..

    A genuine 24/7 rating would be half or less the auto,,, peak for 15 seconds , with no alt or water pump.

    Simplest is to find what the cont rating of a gen set with the engine is,

    or just divide the engines cubic inches by 3 and use that number for cont hp.

    100 cubic inches (CI), probably 33 hp long term.

    The higher the HP taken from an engine the shorter the installed life. 100CI with turbo at 75hp loose 2/3 of engine life.

    The engine can only eat a certain amount of fuel in its lifetime, run it at 2 gph it should last 4X or 5X longer than 8 gph.

    For best efficiency 80% of MFG rated load ( 24/7) at 90% rated RPM is for INDUSTRIAL engines , not car conversions
     
  8. gonzo
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    gonzo Senior Member

    The efficiency depends on many factors and there is no generic percentage. The only way to figure it out is to look at the fuel map.
     
  9. MikeJohns
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    MikeJohns Senior Member


    We use a lot of JD 6.8 Litre at M1 in small fishing boats, the same engines at M4 in liesure boats. From my experience they last as well as any top engine in that power range and a lot longer than the high reving lower torque engines common in liesure boats these days. JD marinetech engines are also quick and cheap to rebuild in situ.

    I'd recommend anything based on the 6068 or 4045 base engines. We can even get a 6068 fully manual non turbo version here.

    If you run a JD at M1 ratings commercially they often give around 10 thousand hours each rebuild.
     

  10. FAST FRED
    Joined: Oct 2002
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    FAST FRED Senior Member

    >The efficiency depends on many factors and there is no generic percentage. The only >way to figure it out is to look at the fuel map.<

    The FUEL MAP for most engine sellers is more secret than plans to build a T-88 Nuclear weapon.

    The MAP is a requirement to select , and set up any engine for efficiency.

    Sadly all most eng. folks will part with is the almost useless prop curve / HP chart.

    Usually (but not always) engines use as 24/7 generators (not emergency power units) will be operated in a fairly efficient band.

    Convert the KW to HP and see if its about what you need at generator operating RPM.

    A 24/7 genset will usually operate at a lower RPM than a standby or emergency unit.

    The JD engines are great , folks with low budgets should remember the factory rebuilt Farm versions (same engines) are usually on sale (NO CORE CHARGE!) 2 or 3x a year and cost loads less.A used rebuilt Twin Disc tranny can be had reasonable too.

    With a dry stack and keel cooling the farm version works as well as the marine with its extra seawater cooling pump, heat exchanger and expen$ive wet exhaust manifold.
     
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