Engine progress and price control

Discussion in 'Propulsion' started by cyclops, Jun 12, 2005.

  1. cyclops
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    cyclops Senior Member

    How many of us are aware of GM's newer engines- auto - being only throw away and not rebuildable? And by logic, marine to become throw away?
  2. mattotoole
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    mattotoole Senior Member

    The engine in almost any modern car will long outlast the rest of the vehicle. Marine engines have far different service requirements, so it's hard to make a comparison.
  3. Corpus Skipper
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    Corpus Skipper Hopeless Boataholic

    How are they not rebuildable? Do they not have bearing inserts???
  4. PowerTech
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    PowerTech Senior Member

    non linered motors suck for boats.but in a car who cares.change your oil and keep it cool they run forever.I got 500,000+ miles on my jap truck and it ain't stoping no time soon.it was baught new in 93 and gets its oil changed.I think all GM products are throw away any way.The new light weight high performance diesels are geting to be throw aways.
  5. kmorin
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    kmorin Senior Member

    GM vs Detroit Deisel

    I've always tried to keep the distinction between the fact that GM has many divisions; including one diesel engine division that makes the Detroit Diesel engines and all the automotive related divisions.

    THe reason for that distinction in my mind is that the DD line was a 10-20k /hr engine if kept up and could be rebuilt to original spec many times if torn down before any catastrophic failures. Some 6-71's have a history of more than 50k hours of actual runtime (<200 hp versions).

    The automotive or passenger car part of GM isn't the best, but their industrial/marine deisel division did make a series of great engines. Now this division is making engines with less durability in mind.

    The engines were actually designed TO BE REBUILT, and the parts were there to do it. I think the newer GM/Detroit Div engines, formerly were so long lived, are now much less robust in terms or total usable life.

    Engines that could run for 30 or 40k hours in the past are now designed to replaced in 5-8k hrs tops. They could be rebuilt, but they're not designed to be rebuilt to new conditions without piston liners and all the other features that lead to their great history.

    A greater design fault in my mind is the horse power to wt ratio of these more recent engines. The reason they last so poorly is the overall mass of the castings is low, the rpm's 'too' high and the load/torque curve needs to be pushed to get the ratings sold. All this contributes to an engine that lasts less and isn't "worth" rebuilding when it needs one.

    progress- right? The good news is you can still buy a half a dozen 6-71's or so for a song, (web search will show hundreds) and there are still very capable mech's around who can restore them. Now that the engines are 'obsolete' the costs are pretty low, the parts are still plentiful and the performance will last my lifetime; I don't need to run an engine designed for 1800 to 2300 at 4.4k rpm to get somewhere enough faster to sacrifice the engine getting there.

  6. fcfc
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    fcfc Senior Member

    Normal trend.

    It is for aircraft engines. Look at http://www.centurion-engines.com/
    You will see they don't have a TBO. The engine is NOT overhaulable. Thay simply have a TBR : Time Between Replacement.

    Now, for my own, I really prefer a 5 000 $ Replacement than a 20 000 $ Overhaul.

    The boats will follow the same trend. See volvo D2, D3, D4 engines. They are automotive blocks factory converted for marine use. What will happen to spare parts (in the event they are partially rebuildable) when theses blocks will be outphased in future cars ? Same for Yanmar 4jh3.

    The next trend is that engine will only be NOT rebuildable, they will become even NOT serviceable. Look what a mechanic shop can do with a common rail diesel injection. Even changing a fuel filter need a vacuum equipment because it must be protected from dust contamination during fitting. I do not speak of OBD diagnostic.

    The engine runs : OK.
    The red light is lit : Call the Coast Guard.
  7. Karl2
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    Karl2 Junior Member

    Of the Volvo engines you mention only the D3 is automotive based.

  8. cyclops
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    cyclops Senior Member

    In all honesty, if I ran the engine depts., I would build the simplest cheapest design that would last only for a reasonable milage. The warrenty period + 1000 miles to trade it in. In boat or planes so many RPM combined with so many hours. Good old days? are coming to a end. Enjoy them.
  9. nevd
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    nevd Junior Member

    Detroit Diesel Ownership and Life


    I wish to take this opportunity to correct some misperceptions.

    Whilst GM did own Detroit, it is now owned by Daimler Chrysler.

    My experience with 71 series GM Diesels has been very bad - all have been turbocharged and some intercooled as well and only the low HP ones could give lives over 10,000 hours when Caterpillar and Cummins had no problems in giving over 15,000 hours in similar applications. Most TI engines could not even get 5,000 hours unless they were detuned. The Detroit 2 strokes (the 71 series was one of the family of 2 strokes) were heavy, noisy, leaky and had high fuel consumption and this is why almost all the Detroit 2 stroke engines have now been dropped from their current range. The last time I checked a few years ago, some of the 149 series were still available.
  10. cyclops
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    cyclops Senior Member

    Every one loved the HD "Diesel" engines they put in Caddies and pickups. Then bought back the vehicles or paid out cash rebates.
  11. fcfc
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    fcfc Senior Member

    Are you chasing the real problem ?

    Per european norm Recreational craft directive 2005, E.B.3.a "The normal life of the engine is considered to mean (a) inboard or stern drive engines with or without integral exhaust : 480 hours or 10 years, whichever occurs first."

    That s about typically 50 hours a year. Not more for boats under 80 ft.

    So rebuilding or replacement is not an issue for 99.999 % of leisure crafts.
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    FAST FRED Senior Member

    Same with most outboards , the mfg expect at max 100 hours per year , with a 10 year service life being the norm.

    Diesels such as the DD , and most others are better concieved as lifetime fuel burners .

    An engine eating 4 to 6 gph will eat as much fuel in its lifetime at the screaming turboed intercooled high rev version that eats 40 to 60 gph.

    The DD had the best setup , you decided service HP required ,
    then chose from a 1,2,3,4,8,6,8,12,16 cylinder version to match the power with the service life desired.

    Problems came when folks wanted to hot rod a smaller engine to keep down the weight.

    With 6-71 many would run fantastic life hours as prime gen sets , ploding all year at 1200rpm with moderate loads.

    1800rpm in commercial fish boats or as gensets or pumps also gives very long life.

    Turn them into a 2300rpm sports fish screamer and 1000 hours TBO is considered fine.

    The very light duty auto Volvos should be able to come close to outboard motor service life.
    10 years to scrap , for cheap stuff isnt bad, but dont scream them or LOAD them beyond the light duty thery were designed/built for, that will get expensive!!

  13. cyclops
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    cyclops Senior Member

    Everyone knows all the design parameters except one. Make ours the fastest, most powerfull for it's size, so every body will pay more money each year for the slightest claimed improvement in performance as demanded by the Sales Department. End of all discussion for this year. Per a directive from our Chief Operations Officer.
  14. gonzo
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    gonzo Senior Member

    Let's look at the good old times: automotive engines lasted 65K miles between rebuilds as opposed to 200k now. Marine engines dumped enough fuel and oil in the water to pay for a new modern engine.

  15. cyclops
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    cyclops Senior Member

    Mostly true. Lets see how many 2005 GM's are still rebuilt and running the way the 50's thru 70's are still being rebuilt and being raced at power levels of up to 500%.
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