modern diesel for small powerboat?

Discussion in 'DIY Marinizing' started by ant123, Sep 6, 2008.

  1. ant123
    Joined: Aug 2008
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    ant123 Junior Member

    hey everyone

    considering putting a modern common rail turbo diesel into an approx 6m/20' trailerboat. would be used for fishing and occasional waterskiing etc. i was put onto the idea by an article in a magazine about a 7m fishing boat with the 1.7L injected diesel mercruiser engine. some incredible economy figures were quoted for trolling use which would be great! im just wanting to know a couple of things, would a diesel also be suitable for short bursts of high load such as pulling up a skiier? and would the economy still be reasonably good when used in this way? also just above planing speed getting to fishing grounds? i would plan on marinising an engine from a modern diesel car around the 2l 120-150hp mark.

    cheers
     
  2. CDK
    Joined: Aug 2007
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    CDK retired engineer

    A common rail diesel will do all that, even better than a gasoline engine and with better fuel economy. Getting into plane is easier and better controlled, you don't need full throttle for it.
    The only drawback is the initial investment. If you've seen the prices for a Mercruiser/Cummins or /Steyr package you understand why most people buy the old-fashioned gas guzzlers.
    To marinize an automobile engine you need:
    A. the complete engine
    B. the ECU with wiring harness and peripheral equipment.
    C. a detailed circuit drawing

    This means that in fact you need the complete car, remove the items you need and bring the rest to the scrap yard.
    You must also have extensive knowledge of electronics because the ECU must be fooled to believe it is still in the car it was programmed for.

    Please keep us informed about the progress once you start the project.
     
  3. ant123
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    ant123 Junior Member

    sounds great! would i need marine starter/alternator etc? ive always wondered if these are necessary with diesels.. i have a fair knowledge of modern gasoline efi engines from wiring up engine conversions in cars, never played with a diesel though, i assume they'd have fairly similar setups? the one thing i can think of that might make things difficult would be the lack of gearbox? and maybe throttle position sensor? what engine would you recommend for a 6m fiberglass boat with a fairly deep v? used mostly at slower cruising speeds but a bit of skiing.
     
  4. FAST FRED
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    FAST FRED Senior Member

    For me the biggest hassle in using a "modern" electronic injected engine would be the Faraday Cage , ans all the protection required to keep it running.

    Perhaps I'm gun shy , living in FL where there are days of 3000+ lightning strikes , any one that could cause DEAD in the water, and require Mucho buck$ to restart with all new computers and injectors.

    Even the high pressure fuel pump is electric , so subject to sudden death.

    A car or truck (or tin fishing trawler) is a better choice to keep an EMP at bay.

    Bring oars,

    FF
     
  5. CDK
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    CDK retired engineer

    Shielding the wiring is a minor detail, just a braid around the cable and a solid ground lug on the engine block. A direct lightning hit will still ruin your engine, but it will do much more than that and you probably wont care about that anymore once it's happened.
    The ECU from a crdi diesel is very similar to that of a gas engine, there is no ignition signal and no air mass sensor, but of course there's different firmware. The missing gearbox is no problem, you can substitute a switch preventing engine start with the stern drive in gear. Cars have an anti-theft system (immobilizer) with a sensing circuit around the key lock. The one from a car you cannot use because it is too large and has a lock for the steering column. You don't want that in your boat, so there you have to improvise a bit.
    As for the engine types: Yanmar uses BMW engines, others like Cummins use something French, found in Peugeot and Renault vehicles, probably a design from Indenor, France. VW-marine uses its own engines of course. The advantage is, that you can buy essential parts like a water cooled exhaust manifold and engine support brackets for these engines.
    For your 18 ft. boat anything that brings more than 100 diesel-hp will do. It will move you at least as fast as a 140 hp Mercruiser gas engine with better acceleration and 30-40% less fuel.
    Look at www.ejbowman.co.uk and www.mesamarine.com to see what is available for small diesel engines.
     
  6. ant123
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    ant123 Junior Member

    just out of interest how big is the difference between the newest common rail diesels and the previous generation of diesels? im not so worried about noise and smoke etc mainly just power/weight and economy. the boat would be used for mainly medium to high speed work. not alot of slow speed trolling etc. is it worth paying extra for common rail? thanks
     
  7. CDK
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    CDK retired engineer

    My VW 1,9 turbo diesels deliver approx. 80 hp, the tdi generation brings 120 hp or more, so the increase is 50% with almost the same engine weight.
    A common rail engine does even better: 135 hp for a standard 1,7 engine, 20-30 hp more if the firmware is replaced.
     
  8. FAST FRED
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    FAST FRED Senior Member

    The top hp may be different but the fuel consumption is more of a concern for cruisers.

    The mechanical injected can get 20hp per gallon if well geared and proped for their task.

    The electric jobbies can crank out 22hp , sometimes better 24 in a very narrow range.

    That IS 10% to 20% "better" but the price of DEAD in the water from a mere nearby flash exists.

    In the big buck boats we met running the loop last summer NONE has their origional computer , some were on the 3 or 4 th replacement.

    All on warentee, after all the engines were new and $40- 50K so the Mfg couldn't avoid the expense.

    FF
     
  9. CDK
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    CDK retired engineer

    You make a lot of negative waves Fred.
    I live in an area where the sky often lights up like a christmas tree, yet none of the electronics in our cars were ever damaged, my home computer and laptops have always survived.
    The isdn telephone box is the only exception. It is replaced approx. 4 times each year because the phone line produces spikes in the 4 KV-up range. But that is an unshielded cable high in the air and 3/4 mile long.

    If the boats you are talking about needed ECU replacements that often, the wiring has not been done the way it should have been. There are several boats with electronic injection in this bay, both gas and diesel; I have not yet heard of a single case of lightning damage.
     
  10. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    If the boats you are talking about needed ECU replacements that often, the wiring has not been done the way it should have been

    Then someone is getting screwed , the boats we talked to were almost new , and well over a million US.

    The use of electronics in motor vehicles seems to seldom have any problems, probably because the metal cage and rubber tires create a good Faraday cage.

    There are lots of trucks and buses with new electrics , because someone used an arc welder , with out disconnecting most everything.

    The steel work boats too seem to have an OK time with electrics , I haven't seen many shrimpers (Series 60 DD with DEDEC ) towed iin.

    But the plastic boats most have offer nothing in the way of protection from a side strike , even one 1/4 mile away.
    Electronics can be destroyed sitting in a slip.

    Weather its worth that extra fuel mileage , ??? hard call, for some , but not for me.

    I travel too many places where the wait for a new $6000 computer box , and $1000 each injectors would be a long wait.

    FF
     
  11. CDK
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    CDK retired engineer

    Fred, you are right about the protective shielding in steel boats, cars etc. That does make electronics less sensitive to electrical discharges.
    But if you know beforehand that your electronics will be installed in a non-conductive vehicle, you can supply the proper materials and give guidelines how it must be installed to obtain the same degree of protection.

    Unfortunately the owner of a million $ yacht in general has no knowledge about trivial matters like cable shielding or how to avoid ground loops. He is more interested in the gadgets at the helm and the size of his flat screen TV that must appear out of nowhere if a button on the remote control is pressed. The easier the customer is willing to part from his money, the less craftsmanship he gets.

    It may also have to do with responsibility and liability to warranty claims. If the people who install the engine were to pay for any repairs made within say 5 years after delivery regardless if the cause, the number of malfunctions would decrease dramatically.
     
  12. Carteret
    Joined: Jan 2004
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    Carteret Senior Member

    I agree with Fred. Mechanical injection is the very best option for the money. May I suggest the GM 6.2 litre V8. Very affordable, easy to come by and dependable in pleasure boat applications. Osco sells manifolds and bell housings for the 6.2/6.5. Stock it will deliver 150 hp and weighs @ 900 lbs. Parts are available at local auto parts stores. Inboard and inboard outboard applications are very doable. I have used one since 2000 and I am averaging about 3 gals an hour fuel rate. On long cruise runs without trolling or idelling we get @ 5 gals an hour fuel rate.
     
  13. TollyWally
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    TollyWally Senior Member

    Carteret,
    You wouldn't have access to the performance curves for that GM Engine would you? I'm interested in the torque figures etc. etc. etc.
     
  14. Carteret
    Joined: Jan 2004
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    Location: Eastern NC

    Carteret Senior Member

    Hey TW,

    try this. http://www.peninsulardiesel.com/marine.html There are 2 or 3 companies that have marinized this engine. But I have seen several 6.2 engines marinized by individuals with Osco marinization kits. For pleasure use this is a very good application. For commercial duty use, I would stick with Cummins, Detroit, Caterpillar etc. Osco's web page is http://www.oscomotors.com/index.asp
    You will find manifolds on page 51 of their catalog. A standard bell housing off of a Chevy big block fits the 6.2/6.5. A 72 series velvet drive works well with this engine also.
     

  15. hmattos
    Joined: Jun 2004
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    Location: Devon UK

    hmattos Senior Member

    This big 6.2 litre will no doubt deliver the 150 hp, but the weight of this engine is questionable. I would like to check that the fully installed weight could be done for 900lbs which is only 410 kg. And would the 6metre boat be capable of carrying it. Here in Europe we make fast RIBs - see www.explorermarine.co.uk - and we would think that a bit heavy even for our very wide boats. It is normal here to be are getting 150 hp out of 1.9 litre car diesel car engines on a regular basis and more if you tweak the mapping.
    Your friends at Cummins have engineered the QSD 2.0 litre series to deliver a sterndrive of 170 hp with an engine only weight of 551 lbs. Have a look at www.CMDmarine.com where they have very good data charts including fuel consumption etc.
    For a cheap solution I would take a VW or Mercedes engine - with its ECU or EMS - from a crashed car and go to my local stainless exhaust maker to bend and weld some home made marinising kit, and get an adapter plate machined to couple to my water jet or stern drive.
    Good luck
    HM
    pretty high for 150 hp. an ETEC outboard of 200 hp weighs only
     
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